Re: Optional Static Typing
Ryan == Ryan Paul [EMAIL PROTECTED] writes: Ryan I wrote a blog post this morning in which I briefly argue Ryan using DbC and predicate based argument constraints instead Ryan of static typing. Take a look I took a look. The first impression is that there is too much stuff to be added to the language, for a relatively unproven methodology (DbC). Yes, observe the herecy in my argument; I'm indeed referring to DbC as being an unproven way to write software. Eiffel never really made it, and explicit preconditions/postconditions haven't really appeared in other languages either. I'm not sure I'd like to see Python (which is not an academic language) take the risk of bloating the language definition with it. Let Ruby, or Boo, or whatever have a go before Python. And yes, I've read my OOSC, and my code has its share of asserts. Type declarations, on the other hand, are as mainstream as one can get. Being optional, they would not brutally murder the spirit of all the good that is Python, contrary to the doom and gloom people have been painting here and elsewhere. The implementation of CPython would become more complex, but I trust the people that are implementing it enough to not be overly concerned. -- Ville Vainio http://tinyurl.com/2prnb -- http://mail.python.org/mailman/listinfo/python-list
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Re: objects as mutable dictionary keys
John Roth schrieb:
No. The basic answer is that it's up to the object whether
it will allow itself to be used as a dictionary key. In other
words, if the designer of an object thinks it makes sense
for instances to be dictionary keys, then he can supply a
__hash__() method. If he doesn't, then he doesn't supply
such a method, and it won't work.
Except for classic objects which can be used as dictionary
keys without having __hash__().
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E-mail 'cGV0ZXIubWFhc0BtcGx1c3IuZGU=\n'.decode('base64')
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Re: popen2, 3, 4 -- will closing all returned streams result in process termination?
[EMAIL PROTECTED] (Evgeni Sergeev) writes: Is there assurance that the process will terminate and not sit in memory orphaned, waiting on its stdin, for example? The process should receive an EOF. It will typically handle EOF by terminating, but that is not guaranteed. -- http://mail.python.org/mailman/listinfo/python-list
Looking for source preservation features in XML libs
Hi. I'm looking for two specific features in XML libraries. One is two be able to tell which source file line a tag starts and ends. Say, tag para is located on line 34 column 7, and the matching /para three lines later on column 56. Another feature is to be able to save the processed XML code in a way that unmodified tags preserve the original identation. Or in the worst case, all identation is lost, but I can control to some degree the outlook of the final XML output. I have looked at xml.minidom, elementtree and gnosis and haven found any such features. Are there libs providing these? -- Please don't send me private copies of your public answers. Thanks. -- http://mail.python.org/mailman/listinfo/python-list
DB-API format string conventions
Hi all I've recently been writing some code that for various reasons needs to support a couple of different PostgreSQL APIs for Python, and have the potential for MySQL support down the track. I've been running into a fair bit of trouble with the DB API, in particular the freedom it gives DB module implementers with regards to Cursor.execute() argument formatting. http://python.org/peps/pep-0249.html says that DB modules must have an attribute paramstyle, to tell the code using the module what string format convention it requires: paramstyle String constant stating the type of parameter marker formatting expected by the interface. Possible values are [2]: There is no discussion, however, of why these _five_ different format styles are permitted, nor any way the calling code might compensate for this. Some APIs seem to support more than one style (PyPgSQL comes to mind here, with both printf+arglist and extended printf+dict support), but there is no apparent way to discover this. Some modules support changing paramstyle, others do not, and there's no spec coverage for this. This seems to my eyes like a fairly major DB API wart, assuming there's no nice way to get around it that I'm not aware of. Do I need to write a format_for_db_API(dbiapi.paramstyle,formatstring) function that converts an extended printf string to whatever the DB API expects, then use that every time I call Cursor.execute() ? If so, is there any chance of the eventual release of a DB API 2.1 that provides a single calling convention that MUST be supported? Any enlightenment on this would be much appreciated. I've found the Python DB API very nice to work with so far (my previous generalised DB API experience being with the DBI:: package in Perl) but this is really frustrating me. If worst comes to worst, I'll just write a simple cursor wrapper that can translate extended printf calls to whatever the DB API requires, but it'd be much nicer not to have to implement something as ugly as that to work around an issue with an otherwise very nice and clear API. Some digging around on Google Groups suggests that others have run into this problem, and quite a few have grumbled about it, but there have been no real answers. So: Would there be any interest in releasing a DB-API 2.1 with one parameter style made MANDATORY, and a tuple of other supported styles in .paramstyles ? I think existing modules implemented in Python could be retrofitted to take extended printf quite easily, though at a small performance cost when extended printf was used. Modules in pure C would be more work, but still probably not a big deal. -- Craig Ringer -- http://mail.python.org/mailman/listinfo/python-list
Re: Tkinter vs wxPython
I am especially interested in terms of learning curve, documentation, portability across platforms Linux/Windows and anything else you care to add. As I know only what I have read on this forum surfing the web I would really appreciate the input of those who have used both, or decided to use one over the other. I was in the same shoes a time ago. I started with Tkinter since is the standard GUI for Python. I read some tutorials, but didn't go to far, and didn't like the Tkinter looks too much. Then I tried wxPython, and things were better. And were much better when I started using wxGlade. IMO, wxPython has a softert learning curve (specially if you use wxGlade), is portable between unix/windows/mac, with the advantage over Tkinter that it has a native look. Regarding documentation, there is plenty of it. I must admit that my background regarding GUIs comes from Delphi, so that might bias my opinion. In case you take the Tkinter route, I founded this tutorial useful : http://www.bembry.org/tech/python/notes/tkinter_1.php Regards, Alejandro. -- http://mail.python.org/mailman/listinfo/python-list
New Meetup Group
This is for Python enthusiasts in the city of Bangalore, the Silicon Valley of India. I have started a new meetup group for Python programming enthusiasts in the city. The group's home page can be accessed at http://python.meetup.com/158/ . If you are a Bangalorean and also a Python enthusiast, consider joining the group. Also, spread the word around. Happy New Year! -Anand -- http://mail.python.org/mailman/listinfo/python-list
Re: Are tuple really immutable?
Thank you. Chris -- http://mail.python.org/mailman/listinfo/python-list
Re: More elegant way to cwd?
Kamilche wrote: Other than using os.pardir instead of '..', and possibly adding an os.path.abspath() call to the last bit (or does realpath already do that? It's unclear from the docs), I can't see anything fundamental I'd do differently... except package these functions up as nice clean subroutines, possibly in a library package, that I could then use in code that would magically become elegant (IMHO) by avoiding the repetition of all that non-elegant stuff above... -Peter Well... but to call it from the shared directory, I'd have to first switch to the shared directory! Which would defeat the purpose. I wish there was a way to store this in a single file and call it from any script, but I'm unwilling to keep all my scripts in one folder to accomodate it. If only Python would let you import modules from different directories. :-/ --Kamilche Maybe I'm misunderstanding your requirements, but it seems to me perfectly practical to keep that script in a standard place (say, lib/site-packages, which was intended for exactly that purpose) and import it from there. There's no reason why its location has to relate to the location of the scripts that import it and use that function from it. What am I missing? regards Steve -- Steve Holden http://www.holdenweb.com/ Python Web Programming http://pydish.holdenweb.com/ Holden Web LLC +1 703 861 4237 +1 800 494 3119 -- http://mail.python.org/mailman/listinfo/python-list
Re: Repainting
LutherRevisited wrote: I have an application that uses a WxListCtrl to hold data that is updated extremely fast. When I run my application the listctrl updates so fast that it practically disappears. Is there a way I can have it update with the user seeing it update rapidly without the dissapearing? Right now I have used the freeze and thaw methods to get rid of that disappearing listctrl problem, only now you have to wait for it to run it's course to see the output. It really isn't critical, I just think it would be a cool visual if the user could see it rapidly updating, I'm beginning to think that because of how rapidly it updates that isn't possible, but if it is I appreciate any help. And you guys would be so proud of me, I actually downloaded the Wx docs and found freeze and thaw all on my own under wxwindows memberslol. That's a quick note out to all that have been patient with me while helping me learn wxpython. Well, the logical approach would seem to be to freeze, add a hundred items, thaw, freeze, add a hundred items, thaw ... [rinse and repeat]. Basically, control the repainting so it only occurs (relatively) infrequently. regards Steve -- Steve Holden http://www.holdenweb.com/ Python Web Programming http://pydish.holdenweb.com/ Holden Web LLC +1 703 861 4237 +1 800 494 3119 -- http://mail.python.org/mailman/listinfo/python-list
Re: DB-API format string conventions
Craig Ringer wrote:
On Tue, 2004-12-28 at 18:29, Craig Ringer wrote:
Would there be any interest in releasing a DB-API 2.1 with one
parameter style made MANDATORY, and a tuple of other supported styles in
.paramstyles ? I think existing modules implemented in Python could be
retrofitted to take extended printf quite easily, though at a small
performance cost when extended printf was used. Modules in pure C would
be more work, but still probably not a big deal.
MySQLdb, psycopg, and pyPgSQL seem to all support 'pyformat' (python
extended printf) though mysql lists 'format' in paramstyle. I'm not able
to test any other DB interfaces at the moment, but if others support
pyformat then perhaps that's a viable choice to make mandatory in a
revision of the spec? That way any code could check for DB-API 2.1 and
know it could use pyformat style in addition to any other styles the
code permitted. Perhaps more importantly, it could also tell Python
programmers they can rely on pyformat style being available.
IMO it'd also be very nice to support **kw calling style, ie to make:
cursor.execute(SELECT somerow FROM table WHERE otherrow = %(name)s,
{'name': 'fred'})
equivalent to:
cursor.execute(SELECT somerow FROM table WHERE otherrow = %(name)s,
name = 'fred')
frankly, I simply think it's a nicer and more readable calling style
when one is passing a list of parameters directly to .execute() rather
than passing an existing dict. That's just a trivial cosmetic thing,
though, and while it'd be nicer the mixing of the two styles may cost
more in confusion than the latter style gains in readability.
So ... anybody for a DB-API 2.1 with mandatory pyformat support and a
tuple dbmodule.paramstyles for supported styles?
Well, you can certainly put me down as supporting less variability in
allowed paramstyles, to the extent that it would allow much more
application portability.
However, you might not be aware that the reason that variability was
included in the first place is to allow Python module authors to take
advantage of features already available in the various underlying
database platform support code - Oracle, for example, already supports
numbered access (:1), and so on.
So be aware that you are asking the various module authors for
significant amounts of work, which may not be forthcoming under all
circumstances.
Also be aware that there have been various post-2.0 proposals for the DB
API, which you might want to look up on Google and fold in to the
current campaign.
regards
Steve
--
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Python Web Programming http://pydish.holdenweb.com/
Holden Web LLC +1 703 861 4237 +1 800 494 3119
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Re: DB-API format string conventions
Craig IMO it'd also be very nice to support **kw calling style, ie to
Craig make:
Craig cursor.execute(SELECT somerow FROM table WHERE otherrow = %(name)s,
Craig{'name': 'fred'})
Craig equivalent to:
Craig cursor.execute(SELECT somerow FROM table WHERE otherrow = %(name)s,
Craigname = 'fred')
Craig frankly, I simply think it's a nicer and more readable calling
Craig style when one is passing a list of parameters directly to
Craig .execute() rather than passing an existing dict.
In my code I most often use locals() to map the local namespace into a
dictionary:
cursor.execute(SELECT somerow FROM table WHERE otherrow = %(name)s,
locals())
That works as long as there's a local variable named name in the local
namespace.
Craig So ... anybody for a DB-API 2.1 with mandatory pyformat support
Craig and a tuple dbmodule.paramstyles for supported styles?
The sybase-python module supports Sybase's @ thingie in a straightforward
way:
cursor.execute(SELECT somerow FROM table WHERE otherrow = @name,
{@name: fred})
This works for both selects as well as for the input and output parameters
of stored procedures (cursor.callproc).
Skip
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Re: DB-API format string conventions
On Tue, 28 Dec 2004 19:08:10 +0800,
Craig Ringer [EMAIL PROTECTED] wrote:
IMO it'd also be very nice to support **kw calling style, ie to make:
cursor.execute(SELECT somerow FROM table WHERE otherrow = %(name)s,
{'name': 'fred'})
equivalent to:
cursor.execute(SELECT somerow FROM table WHERE otherrow = %(name)s,
name = 'fred')
frankly, I simply think it's a nicer and more readable calling style
when one is passing a list of parameters directly to .execute() rather
than passing an existing dict. That's just a trivial cosmetic thing,
though, and while it'd be nicer the mixing of the two styles may cost
more in confusion than the latter style gains in readability.
I am in no way an expert in this area, but after a round or two of
abstracting, layering, and refactoring, I can't recall having an
explicit list of parameters that close to an SQL literal or a call to
cursor.execute.
I usually end up with a back-end that maps higher level constructs,
like dicts or other objects, to database concepts, like rows and tables.
At best, the top of the back-end knows about the higher level
constructs creates lists of column names and passes dictionary-like
objects down the bottom of the back-end and functions that build SQL
code from lists of column names, interact with the database, trap common
errors, write to logs, etc. Those lower level functions know about
cursors and result sets, and can [relatively] easily turn rows from the
database into dictionaries based on nothing but information in the
cursor (and maybe some help from a callback function or object factory).
OTOH, I am a very big fan of the cohesion and layering concepts I
learned from years and years of structured programming, and a lot of my
ideas of what should be separate from what have fallen by the wayside.
So ... anybody for a DB-API 2.1 with mandatory pyformat support and a
tuple dbmodule.paramstyles for supported styles?
I'd be all for that, but I'm not holding my breath. ;-)
Regards,
Dan
--
Dan Sommers
http://www.tombstonezero.net/dan/
Never play leapfrog with a unicorn.
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[Fwd: Re: DB-API format string conventions]
[posted after mailing response in error] Craig Ringer wrote: On Tue, 2004-12-28 at 21:16, Steve Holden wrote: So ... anybody for a DB-API 2.1 with mandatory pyformat support and a tuple dbmodule.paramstyles for supported styles? Well, you can certainly put me down as supporting less variability in allowed paramstyles, to the extent that it would allow much more application portability. However, you might not be aware that the reason that variability was included in the first place is to allow Python module authors to take advantage of features already available in the various underlying database platform support code - Oracle, for example, already supports numbered access (:1), and so on. I'm not actually against the number of choices available, I'm just concerned that there is currently no _single_ choice that can be guaranteed to work, and that it's hard to identify all styles a given API supports. Of course, even if one does confine ones self strictly to what can be guaranteed to work in the DB API, there are a multitude of differences in database SQL syntax and extensions to worry about. That is an issue any programmer will face - not just a Python DB-API 2.0 user, and I see it as a separate issue. Tackling that would involve building a DB abstraction layer like the various query builders available for Java - a very interesting, but much bigger, job that I'm not even remotely interested in looking at right now ;-) Though you might care to look at Chapter 11 of Python Web Programming when you have time, where I had a go at such an abstraction layer. It was moderately successful across a number of platforms. So be aware that you are asking the various module authors for significant amounts of work, which may not be forthcoming under all circumstances. That's true, and something I'm keeping in mind. I'd be quite happy to implement the required changes for modules I'm familar with to help with that issue. That's good. That said, if pyformat was chosen as the required style it might not be too big a job at all. Many modules already support pyformat though not all advertise the fact, and for them it may be as simple as bumping the API version to 2.1 and adding a module-level var containing a tuple of all supported styles. We can but hope. I'm afraid I'm less optimistic than you, but this lack of optimism shouldn't be allowed to restrain your enthusiasm. Also be aware that there have been various post-2.0 proposals for the DB API, which you might want to look up on Google and fold in to the current campaign. Indeed. I went looking for proposals specifically related to argument handling earlier, but still need to have a look for other API revision proposals. I thought it best to ask here to find out how much interest there would be in clarifying the API and adding a required format style before going ahead with actually writing a few patches and a draft PEP for comments. Well, let's hope I'm not the only one to respond, then. Since the push for 2.5 is allegedly to improve the standard library, it would be great if we could improve the portability of the DB API as well. I'd personally be in favor of trying to include a number of database modules either in the standard library or in a package that could easily be added in a lump. Go to it, and good luck - let me know when you need help. regards Steve -- Steve Holden http://www.holdenweb.com/ Python Web Programming http://pydish.holdenweb.com/ Holden Web LLC +1 703 861 4237 +1 800 494 3119 -- Steve Holden http://www.holdenweb.com/ Python Web Programming http://pydish.holdenweb.com/ Holden Web LLC +1 703 861 4237 +1 800 494 3119 -- http://mail.python.org/mailman/listinfo/python-list
Q: Scheduling in scipy.cow
Dear NG, can somebody tell me how the work packages are scheduled to the workers? From the code it seems to me like a a static distribution, ie each worker gets the same amount of work, not taking into account if a faster worker already finished all work packages. Thanks, Mathias PS: Is there a better NG for scipy related questions, espescially scipy.cow? -- http://mail.python.org/mailman/listinfo/python-list
Re: argument type
It's me wrote: No, that was just an example. I actually have additional arguments that are similar to arg2. It's not like I can do: def abc(arg1, arg3, *arg2s, *arg3s, *arg4s) ... Now, what if arg2 is not a string but either a number or a bunch of numbers? Using your method, can I say something to the effect of if arg2 is *not* an instance of a simple number? Methinks you are trying to shove a 5 bushel problem in a 2 bushel sack. Take a deep breath. Get a cup of coffee. Read the newspaper. Come back in 10-15 min and re-examine the problem with a fresh mind. Do you really have to pass multiple, variable sized lists of varying types to the same function? Is there some way to break the function into simpler pieces? Is there some better way to organize the program as a whole so that you avoid the issue altogether - perhaps by defining a new class? It's been my experience that whenever I'm confused on how I'm going to pass a number of parameters to a function, the function is too complex and needs to be simplified, either by splitting it up into simpler functions, or by moving functionality into object methods. In the end, the program not only does what I want, but is also easier to understand. -- http://mail.python.org/mailman/listinfo/python-list
Re: Looking for source preservation features in XML libs
Grzegorz Adam Hankiewicz wrote: I'm looking for two specific features in XML libraries. One is two be able to tell which source file line a tag starts and ends. Say, tag para is located on line 34 column 7, and the matching /para three lines later on column 56. Another feature is to be able to save the processed XML code in a way that unmodified tags preserve the original identation. Or in the worst case, all identation is lost, but I can control to some degree the outlook of the final XML output. I have looked at xml.minidom, elementtree and gnosis and haven found any such features. Are there libs providing these? here's a custom parser that adds a lineno attribute to element nodes: from elementtree import XMLTreeBuilder class MyParser(XMLTreeBuilder.FancyTreeBuilder): def start(self, elem): elem.lineno = self.lineno def parse(file): # feed one line at a time, and keep track of the line number lineno = 1 parser = MyParser() for line in open(file).readlines(): parser.lineno = lineno parser.feed(line) lineno = lineno + 1 return parser.close() for elem in parse(samples/simple.xml).getiterator(): print elem.tag, elem.lineno (the FancyTreeBuilder is somewhat broken in 1.2.1 through 1.2.3, at least if you're using Python 2.3 or later. or in other words, use ElementTree 1.2 or 1.2.4 if you want this to work). the standard elementtree writer may modify the tags, but it preserves all whitespace around them; depending on what you mean by indentation, that may or may not be what you want. (but if you want to preserve all whitespace in an XML document, you shouldn't run it through an XML parser...) /F -- http://mail.python.org/mailman/listinfo/python-list
code Generator Help
Code Generators!!! I think now a days programmers should prefer Code Generator to do their coding rather than doing everything by hand. They are almost generator for every database. If you do n't have enough time write all the code by hand, invest some in code genetor and make you lifew easy. I just want to share my thought with this user group. You are welcome to send me an email about it [EMAIL PROTECTED] My favorite is TierDeveloper from www.alachisoft.com Here are some of features list on their website and I just copy paste it here. Cheers, Single multi-table object mapping Unmapped objects (creates tables in db for them) Map objects to views as updateable Formula fields Identity, sequences, and trigger changed columns Static object queries 1-1, n-1, 1-n, and m-n relationships Stored procedure calls Bulk update and delete methods Custom load, insert, and update operations Datasets and Typed Datasets .NET components for COM+ .NET standalone components (for Windows Forms etc.) Export DDL scripts (New) Integrated SQL tool Database validation and synchronization Generate ASP.NET application Generate Windows Forms application Generate HTML design doc for objects C# and VB.NET support SQL Server 7.0/2000 (SQLClient) Microsoft Access (OLEDB) SQL Server 7.0/2000 (OLEDB) Oracle 8i/9i (OLEDB OracleClient) DB2 7.x/8.1 (OLEDB) (New) Multiple databases in one project 100% VS.NET 2002/2003 integration Dynamic object queries Web services for objects Custom hooks (safe from code generation) Generate stored procedures for SQL Parent/Child relationship life-cycle mgmt Generate Windows Forms remote client (New) Customize ASP.NET application GUI (New) Customize Windows Forms application GUI (New) Customize Windows Forms remote client GUI (New) -- http://mail.python.org/mailman/listinfo/python-list
Re: HELP Non-Blocking reads from sys.stdin in Windows.
hi Do you mean something like the following. class inputReader(Thread): def __init__(self): Thread.__init__(self) def run(self): buffer = sys.readline() thread = inputReader() thread.start() Thanks Kwame Paul Rubin http://[EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] barr [EMAIL PROTECTED] writes: I am in real need of a way to perform non blocking reads from sys.stdin on windows. I have looked every where for an answer but but with no luck. I beleive there there must be a way of doing this, can some one please help asap. Use a separate thread. -- http://mail.python.org/mailman/listinfo/python-list
Re: Tkinter vs wxPython
In article [EMAIL PROTECTED], Alejandro Weinstein [EMAIL PROTECTED] wrote: . . . the standard GUI for Python. I read some tutorials, but didn't go to far, and didn't like the Tkinter looks too much. Then I tried . . . IMO, wxPython has a softert learning curve (specially if you use wxGlade), is portable between unix/windows/mac, with the advantage over Tkinter that it has a native look. Regarding documentation, . . . While people seem to mean a range of different things when they write, Tkinter doesn't look 'native', most of them are being addressed in revisions currently underway. In fact, new look- and-feel are available in early releases for those interested in experimentation. -- http://mail.python.org/mailman/listinfo/python-list
Re: code Generator Help
[EMAIL PROTECTED] wrote: Code Generators!!! I think now a days programmers should prefer Code Generator to do their coding rather than doing everything by hand. They are almost generator for every database. If you do n't have enough time write all the code by hand, invest some in code genetor and make you lifew easy. I just want to share my thought with this user group. You are welcome to send me an email about it [EMAIL PROTECTED] My favorite is TierDeveloper from www.alachisoft.com Here are some of features list on their website and I just copy paste it here. [feature list etc. snipped] If this isn't spam I'll eat my hat. How many other irrelevant newsgroups has this been sent to? Headers follow for abuse tracking and retribution. regards Steve Path: news1.east.cox.net!east.cox.net!filt02.cox.net!peer01.cox.net!cox.net!cyclone1.gnilink.net!gnilink.net!news.glorb.com!postnews.google.com!z14g2000cwz.googlegroups.com!not-for-mail From: [EMAIL PROTECTED] Newsgroups: comp.lang.python Subject: code Generator Help Date: 28 Dec 2004 07:56:18 -0800 Organization: http://groups.google.com Lines: 91 Message-ID: [EMAIL PROTECTED] NNTP-Posting-Host: 203.215.172.162 Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 X-Trace: posting.google.com 1104249382 1818 127.0.0.1 (28 Dec 2004 15:56:22 GMT) X-Complaints-To: [EMAIL PROTECTED] NNTP-Posting-Date: Tue, 28 Dec 2004 15:56:22 + (UTC) User-Agent: G2/0.2 Complaints-To: [EMAIL PROTECTED] Injection-Info: z14g2000cwz.googlegroups.com; posting-host=203.215.172.162; posting-account=7YudzA0fMdqpJCBHcNyqldiXgatK Xref: cox.net comp.lang.python:394356 X-Received-Date: Tue, 28 Dec 2004 10:56:24 EST (news1.east.cox.net) -- Steve Holden http://www.holdenweb.com/ Python Web Programming http://pydish.holdenweb.com/ Holden Web LLC +1 703 861 4237 +1 800 494 3119 -- http://mail.python.org/mailman/listinfo/python-list
Re: Making pygopherd working with Mac OS X
[EMAIL PROTECTED] (mattabat) writes: I attempted to use pygopherd 2.0.9 work with MacPython 2.3 under Mac OS X 10.3.7 but I'm afraid I hit a brick wall trying to make it run. Does anyone know how to make this work? I obtained pygopherd from gopher://gopher.quux.org/1/devel/gopher/pygopherd - or for the gopher client deprived, from http://gopher.quux.org:70/devel/gopher/pygopherd Has anyone managed to get pygopherd running with MacPython? You might subscribe to the complete.org mailing list; John Goerzen reads there. See gopher://gopher.quux.org/0/Software/Gopher/Mailing%20List.txt -- Cameron Kaiser * [EMAIL PROTECTED] * posting with a Commodore 128 personal page: http://www.armory.com/%7Espectre/ ** Computer Workshops: games, productivity software and more for C64/128! ** ** http://www.armory.com/%7Espectre/cwi/ ** -- http://mail.python.org/mailman/listinfo/python-list
Re: Best GUI for small-scale accounting app?
On Dec 27, 2004, at 5:01 PM, JanC wrote: IMHO this is the worst think for the Python community: you can find one Python only with an excellent support. Great But on the other hand it is possible to find plenty of GUI tools and for the beginner (and may be not just for the beginner) it is so hard to choose the proper one! The field of GUI tools is so fragmented I think the field of GUI frameworks / tools for Python is fragmented because it's fragmented outside of Python too... I think that the reason things are fragmented in this field is that none of the tools are simple enough to learn. They require a great deal of studying, experimentation, re-coding, Googling, etc., in order to create your first non-trivial GUI app. Once you've gone through all that, you'll probably not want to start over again with another tool, since you'll face a similar ordeal with that tool. This was one of our motivations in developing Dabo: making a tool that was easy for any competent Python developer to pick up in a short period of time. We're using the wxPython toolkit as the underlying UI toolkit, but wrapping as much of it as we can to make the interface to the Dabo UI simple. We're also wrapping it to make it independent of the underlying UI toolkit; ideally, the same code should work for TkInter, wxPython, Qt, etc. For example, I spent yesterday developing the menu classes. Here's an example of the wxPython code necessary to create a menu and add an item to it that calls a particular method when chosen: menu = wx.Menu() itmID = wx.NewId() itm = wx.MenuItem(menu, itmID, text=Close Window) self.Bind(EVT_MENU, self.onCloseWindow, itmID) Here's the equivalent in Dabo: menu = dabo.ui.dMenu() itm = menu.append(Close Window, self, self.onCloseWindow) Note that there is nothing wxPython-ish about the Dabo code. The goal is to make GUI development as simple as Python development. If we can reach that goal (and yes, I'm quite aware of the difficulty involved), it is my belief that there is a good chance that we will reach a critical mass where enough people are using the tool that it may become a 'standard'. ___/ / __/ / / Ed Leafe http://leafe.com/ http://dabodev.com/ -- http://mail.python.org/mailman/listinfo/python-list
Re: A Revised Rational Proposal
John Roth [EMAIL PROTECTED] writes: Mike Meyer [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] Nick Coghlan [EMAIL PROTECTED] writes: Mike Meyer wrote: Yup. Thank you. This now reads: Regarding str() and repr() behaviour, repr() will be either ''rational(num)'' if the denominator is one, or ''rational(num, denom)'' if the denominator is not one. str() will be either ''num'' if the denominator is one, or ''(num / denom)'' if the denominator is not one. Is that acceptable? Sounds fine to me. On the str() front, I was wondering if Rational(x / y) should be an acceptable string input format. I don't think so, as I don't see it coming up often enough to warrant implementing. However, Rational(x / y) will be an acceptable string format as fallout from accepting floating point string representations. How would that work? I though the divide would be evaluated before the function call, resulting in an exception (strings don't implement the / operator). That was a mistake on my part. It would be Rational(x, y). mike -- Mike Meyer [EMAIL PROTECTED] http://www.mired.org/home/mwm/ Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information. -- http://mail.python.org/mailman/listinfo/python-list
Re: argument type
Rocco, your comment noted. Okay, I got what I need to know for this issue. Thanks everybody for your help. I greatly appreciate it. Rocco Moretti [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] It's me wrote: No, that was just an example. I actually have additional arguments that are similar to arg2. It's not like I can do: def abc(arg1, arg3, *arg2s, *arg3s, *arg4s) ... Now, what if arg2 is not a string but either a number or a bunch of numbers? Using your method, can I say something to the effect of if arg2 is *not* an instance of a simple number? Methinks you are trying to shove a 5 bushel problem in a 2 bushel sack. Take a deep breath. Get a cup of coffee. Read the newspaper. Come back in 10-15 min and re-examine the problem with a fresh mind. Do you really have to pass multiple, variable sized lists of varying types to the same function? Is there some way to break the function into simpler pieces? Is there some better way to organize the program as a whole so that you avoid the issue altogether - perhaps by defining a new class? It's been my experience that whenever I'm confused on how I'm going to pass a number of parameters to a function, the function is too complex and needs to be simplified, either by splitting it up into simpler functions, or by moving functionality into object methods. In the end, the program not only does what I want, but is also easier to understand. -- http://mail.python.org/mailman/listinfo/python-list
Re: Are tuple really immutable?
Chris [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] Thank you. To who? All of us? Many have posted on this thread. With previously downloaded and read messages suppressed or deleted, quoteless messages like this are rather unclear ;-) Terry J. Reedy -- http://mail.python.org/mailman/listinfo/python-list
Re: Best GUI for small-scale accounting app?
Ed Leafe [EMAIL PROTECTED] writes: Here's the equivalent in Dabo: menu = dabo.ui.dMenu() itm = menu.append(Close Window, self, self.onCloseWindow) This still seems way too complicated. Why execute a bunch of separate statements when what you're trying to set up is a single structure? E.g.: menu = dabo.ui.Menu((Close Window, self.onCloseWindow), (New Window, self.NewWindow), (Print, self.Print)) -- http://mail.python.org/mailman/listinfo/python-list
Re: PyJuggler 1.0 Beta 1 available
Following up on the release of VR Juggler 2.0 Beta 1, I am pleased to announce the release of PyJuggler 1.0 Beta 1. ... What is PyJuggler? -- PyJuggler is an extension to VR Juggler I started in my spare time one weekend in November 2002. ... Using PyJuggler, it is possible to write a VR Juggler application object in Python and load the object into the VR Juggler kernel, which of course is written in C++. ... Thanks. Just missing what VR Juggler is. From http://www.vrjuggler.org/ : VR Juggler provides virtual reality (VR) software developers with a suite of application programming interfaces (APIs) that abstract, and hence simplify, all interface aspects of their program including the display surfaces, object tracking, selection and navigation, graphics rendering engines, and graphical user interfaces. An application written with VR Juggler is essentially independent of device, computer platform, and VR system. VR Juggler may be run with any combination of immersive technologies and computational hardware. Ah, I see now. Thanks again. ;-) -- Nicola Larosa - [EMAIL PROTECTED] Using Unix is the computing equivalent of listening only to music by David Cassidy. -- Rob Pike on Slashdot, October 2004 -- http://mail.python.org/mailman/listinfo/python-list
Re: built-in 'property'
Stian Søiland wrote: On 2004-12-28 12:05:20, [EMAIL PROTECTED] wrote: class NOTOK(object): def __init__(self): self.__x = 0 self.x = property(self.getx, self.setx, self.delx, I'm the 'x' property.) def getx(self): return self.__x - 5 def setx(self, value): self.__x = value + 10 def delx(self): del self.__x I seem to be missing some of the messages on this thread, but while we're talking about properties, it's probably instructive to remind people that the functions passed to the property function are not redefinable in subclasses: py class D(C): ... def getx(self): ... return 42 ... py D(5).x 5 py class C(object): ... def getx(self): ... return 1 ... x = property(getx) ... py class D(C): ... def getx(self): ... return 42 ... py C().x 1 py D().x 1 Note that even though I redefined getx in class D, the 'x' property is still using the function C.getx that was passed into it. For this reason, I usually suggest declaring properties like[1]: py class E(object): ... def x(): ... def get(self): ... return float(self._x) ... def set(self, x): ... self._x = x**2 ... return dict(fget=get, fset=set) ... x = property(**x()) ... def __init__(self, x): ... self._x = x ... py e = E(42) py e.x 42.0 py e.x = 3 py e.x 9.0 Note that by using the x = property(**x()) idiom, I don't pollute my class namespace with get/set/del methods that aren't really useful to instances of the class. It also makes it clear to subclasses that if they want different behavior from the x property that they'll need to redefine the entire property, not just a get/set/del method. Steve [1] Thanks to whoever originally suggested this! Sorry, I've forgotten who... -- http://mail.python.org/mailman/listinfo/python-list
Re: Lambda going out of fashion
In article [EMAIL PROTECTED], Alex Martelli [EMAIL PROTECTED] wrote: [EMAIL PROTECTED] wrote: Thanks. :-) Two remarks. o One-liner fits the eyes brains of a portion of people. True! So, personally, I'd rather code, e.g., def bools(lst): return map(bool, lst) rather than breal this one-liner into two lines at the colon, as per standard Python style. However, uniformity has its advantages, too; I'm ready for the one-liner style to be outlawed in Python 3.0, purely in the advantage of uniformity. Note that lambda is utterly useless here, be it for one-liners or not. . . . Please say that last sentence another way. I *think* you mean that to define (def) a non-pathologic named function, lambda provides no advantage; one sacrifices no expressivity by a restriction to def-s. Is that right? -- http://mail.python.org/mailman/listinfo/python-list
Reference behavior through C (was: Lambda going out of fashion)
In article [EMAIL PROTECTED], Craig Ringer [EMAIL PROTECTED] wrote: . . . IMO the reference behaviour of functions in the C API could be clearer. One often has to simply know, or refer to the docs, to tell whether a particular call steals a reference or is reference neutral. Take, for example, PyDict_SetItemString vs PyMapping_SetItemString . Is it obvious that one of those steals a reference, and one is reference neutral? Is there any obvious rationale behind this? I'm not overflowing with useful suggestions about this, but I do think it'd be nice if there was a way to more easily tell how functions behave in regard to reference counts. . . . This is a sensitive area for me, too. I'd welcome insight on how to think about this. If Pythonia were a better place in this regard, how would it be? Reference documents that more transparently define reference behavior? A convention for API names that reveals reference characteristics? Is there someone who's confident with Python use through C that has a reliable process for getting reference counts right? -- http://mail.python.org/mailman/listinfo/python-list
Re: Best GUI for small-scale accounting app?
Ed Leafe [EMAIL PROTECTED] writes: Oh, geez. After months of us getting skewered for releasing Dabo under GPL, with everyone saying that they wouldn't even *look* at it for fear of 'infecting' all of their code, we change the license to the MIT license, and now the complaint is that Microsoft is going to sell the code! Well, those are commercial developers who are afraid of the GPL. If they want to require people to pay to use the code they release, then they, just like Microsoft, should also expect to pay the developers of the components they use. If I were you I would have stood firm on the GPL, unless they offered you funding. Ever get that feeling that you can't win? ;-) I don't see how you lose with the GPL, unless you count missing out on the exciting opportunity to be an unpaid employee of someone else's corporation, without even getting back improvements made to your code. I hope Dabo can read the xml files Glade generates, so you have a gui builder that's already deployed. That's definitely part of the development plan. But after looking at Glade and several other designers, our conclusion is that they all lack something: either flexibility, ease of use, or something else. Sizers were probably the item that was the most difficult thing to handle well. The best designer for sizers we found was Qt Designer. We'd like to make our designer as visually clear as that one. I'm not sure what sizers are, but why not just add them to Glade? Also, Dabo is not just a UI toolkit: it's a full 3-tier application framework. Our major design goal is to integrate the database connections defined into the UI designer, so that you can drag and drop fields from the tables in the connection onto the design surface, and create data-bound controls in one step. Ehhh, sounds a little too much like javabeans :). -- http://mail.python.org/mailman/listinfo/python-list
Re: Python IDE
On the subject can somebody here who uses SPE (or just has some python knowledge) help me out with the installation process? I tried following http://spe.pycs.net/extra/manual/manual.html#windows but end up with the error: python /c/system/python24/Lib/site-packages/_spe/winInstall.py Traceback (most recent call last): File /c/system/python24/Lib/site-packages/_spe/winInstall.py, line 1, in ? import info File /c/system/python24/Lib/site-packages/_spe/info.py, line 1, in ? import os,sys,sm.osx ImportError: No module named sm.osx interestingly enough there is an osx.py in PYTHON_DIR/Lib/site-packages/sm so I figure I may just have python configured poorly somehow. Any ideas on where I should look? -- http://mail.python.org/mailman/listinfo/python-list
python sane imaging
Anyone know where the python sane imaging module is? Searching google, I can't find it to download. I have a win32 linux system -- hope to find it for both OSes. Dave -- http://mail.python.org/mailman/listinfo/python-list
consequences of not calling object.__init__?
So when I'm writing a class and I define an __init__ method, I sometimes haven't called object.__init__, e.g.: class C(object): def __init__(self, x): self.x = x instead of class C(object): def __init__(self, x): super(C, self).__init__() self.x = x Looking at: http://www.python.org/2.2.3/descrintro.html#__new__ The built-in type 'object' has a dummy __new__ and a dummy __init__ seems to suggest that the super call here is unnecessary. It's also not made in the Super class example from that document: http://www.python.org/2.2.3/descrintro.html#superexample I'm trying to get in the habit of calling super in all __init__ methods, but it seems like it's unnecessary when the only superclass is object. Assuming that the base class of C doesn't get changed from object, are there consequences of not making this call? Steve -- http://mail.python.org/mailman/listinfo/python-list
Re: DB-API format string conventions
On Tue, 28 Dec 2004 22:02:59 +0800 Craig Ringer [EMAIL PROTECTED] wrote: I'm not actually against the number of choices available, I'm just concerned that there is currently no _single_ choice that can be guaranteed to work, and that it's hard to identify all styles a given API supports. http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/278612 -- Denis S. Otkidach http://www.python.ru/ [ru] -- http://mail.python.org/mailman/listinfo/python-list
Re: Python IDE
On the subject can somebody here who uses SPE (or just has some python knowledge) help me out with the installation process? I tried following http://spe.pycs.net/extra/manual/manual.html#windows but end up with the error: python /c/system/python24/Lib/site-packages/_spe/winInstall.py Traceback (most recent call last): File /c/system/python24/Lib/site-packages/_spe/winInstall.py, line 1, in ? import info File /c/system/python24/Lib/site-packages/_spe/info.py, line 1, in ? import os,sys,sm.osx ImportError: No module named sm.osx interestingly enough there is an osx.py in PYTHON_DIR/Lib/site-packages/sm so I figure I may just have python configured poorly somehow. Any ideas on where I should look? -- http://mail.python.org/mailman/listinfo/python-list
Re: consequences of not calling object.__init__?
in the code that follows, instances of E haven't been through D's rigorous initiation process .class C(object): .def __init__(self): .print C . .class D(object): .def __init__(self): .print D .super(D, self).__init__() . .class E(C, D): .def __init__(self): .print E .super(E, self).__init__() -- http://mail.python.org/mailman/listinfo/python-list
Re: consequences of not calling object.__init__?
Steven Bethard wrote: So when I'm writing a class and I define an __init__ method, I sometimes haven't called object.__init__, e.g.: class C(object): def __init__(self, x): self.x = x instead of class C(object): def __init__(self, x): super(C, self).__init__() self.x = x Looking at: http://www.python.org/2.2.3/descrintro.html#__new__ The built-in type 'object' has a dummy __new__ and a dummy __init__ seems to suggest that the super call here is unnecessary. It's also not made in the Super class example from that document: http://www.python.org/2.2.3/descrintro.html#superexample I'm trying to get in the habit of calling super in all __init__ methods, but it seems like it's unnecessary when the only superclass is object. Assuming that the base class of C doesn't get changed from object, are there consequences of not making this call? The principal one that I can see is that you are relying on this implementation feature to maintain forward compatibility, since I'm not aware of any pronouncement that says object will *always* have a dummy __init__. There's also the possibility that you might want to use a different base class later (for example, setting object = mySuperDebugObject for debugging purposes). If that object has an __init__() method you'll have to put the calls in then anyway. Perhaps a relevant question is how long it takes to call the __init__ method using super. [EMAIL PROTECTED] ~/Projects/PyCON2005 $ python /usr/lib/python2.4/timeit.py -s class C(object): def __init__(self, x): self.x = x C(1) 10 loops, best of 3: 2.69 usec per loop [EMAIL PROTECTED] ~/Projects/PyCON2005 $ python /usr/lib/python2.4/timeit.py -s class C(object): def __init__(self, x): super(C, self).__init__() self.x = x C(1) 10 loops, best of 3: 5.58 usec per loop So, even on my cronky old 1.3 GHz laptop [1] you only lose 3 microseconds per object creation. You'll have to decide how significant that is. regards Steve [1]: Freaky - I had just typed this when the doorbell went, and it was the UPS driver delivering the new laptop! -- Steve Holden http://www.holdenweb.com/ Python Web Programming http://pydish.holdenweb.com/ Holden Web LLC +1 703 861 4237 +1 800 494 3119 -- http://mail.python.org/mailman/listinfo/python-list
Re: popen2, 3, 4 -- will closing all returned streams result in process termination?
It depends mostly on how the spawned process handles conditions like closed pipes, EOF, etc. In general and on *nix, any spawned and terminated process will become and remain a zombie until reaped, i.e. until the final status is collected by a calling os.waitpid(). To avoid zombies, you should call the poll() or wait() method of the Popen3 object created for each spawned process or call os.waitpid(). The problem is that the popen* functions only return the pipe objects and not the Popen3 instance nor the process id. Take a look at the source code of the popen2 module which is the file .../Lib/popen2.py in your python installation. It is straightforward to create your own popen* functions and keep the Popen3 instance. /Jean Brouwers In article [EMAIL PROTECTED], Evgeni Sergeev [EMAIL PROTECTED] wrote: After I opened streams to a process using popen2, popen3 or popen4, will closing every one of the streams terminate the process? Is there assurance that the process will terminate and not sit in memory orphaned, waiting on its stdin, for example? Evgeni Sergeev -- http://mail.python.org/mailman/listinfo/python-list
(no subject)
-- http://mail.python.org/mailman/listinfo/python-list
Re: code Generator Help
Steve Holden wrote: If this isn't spam I'll eat my hat. How many other irrelevant newsgroups has this been sent to? Headers follow for abuse tracking and retribution. More precisely, the email is from a marketer in Pakistan. http://www.pid.org.pk/resume.html Note the lack of programming experience. The software mentioned comes from Alachisoft which is a subsidiary of Diyatech which does its software development in South Asia. Andrew [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: Tkinter vs wxPython
Esmail Bonakdarian [EMAIL PROTECTED] schrieb im Newsbeitrag news:[EMAIL PROTECTED] Hi I have found ALL of the posts useful, thank you so much. Please keep them coming! I am learning a lot. I will probably play a bit with Tkinter and wxPython and see how each feels, just as Peter Hansen suggested). PyQt also looks It couldn't have been said better than Peter has. I might add this: Try both *and learn both*. Despite the fact, that I do most GUI stuff with wxPython, I sometimes face situations, where I need to be able to do some Tkinter stuff (mostly by use of PMW). This could happen to you too, more likely than you might think now. As for the wxPython path: I recently prototyped a GUI-app for Windows with wxPython and then (alas) had to port it to C++. I simply could download the wxWidgets (which wxPython is built upon) and kind of simply translate the Python stuff into C++! It really helped me *a lot* having a working wx/Python app, and saved me a lot of time, of course (but no as much as I had saved, if I hadn't to port it to C++). And while I am at it: It was a big benefit for me to *not* use a GUI builder (which could be the next thing you might ask for), when I started Python programming. When I started Python programming with 1.5.2 there wasn't a descent GUI builder for wx (or at least I couldn't find one). And today, where there are a few options (wxDesigner, Boa, to be concrete), I'm really glad never having used one: Everything I do is under *my* full control, and I guess this is the only way to get the most out of wx/Python. And for sure, it's the only way knowing what you do. As Peter said, the wxPython demo is a bonanza - use it. Summary: Taking all my experience into account, I'd advise you to learn Tkinter, to learn wxPython and to not use a GUI builder (which could be not what a newbie likes to hear). HTH Franz GEIGER P.S.: Concerning PyQt: Yes, so far I only can speak for Tkinter and wxPython. But as soon as I will be on Linux (hopefully next year), I'll try PyQt. So if you would have asked me next year, I had said (phew, is that correct English?): Learn Tkinter and wxPython and/or PyQt and no GUI builder :-) interesting, so I will take a look at that at some point down the line aswell. Thanks again, this is a great resource. Esmail -- http://mail.python.org/mailman/listinfo/python-list
A scoping question
This must be another newbie gotchas. Consider the following silly code, let say I have the following in file1.py: #= import file2 global myBaseClass myBaseClass = file2.BaseClass() myBaseClass.AddChild(file2.NextClass()) #= and in file2.py, I have: #= global myBaseClass class BaseClass: def __init__(self): self.MyChilds = [] ... def AddChild(NewChild): self.MyChilds.append(NewChild) ... class NextClass: def __init__(self): for eachChild in myBaseClass.MyChilds: # - ERROR ... #= When I run this, Python complains that myBaseClass is undefined in the last line above. What am I doing wrong? (Yes, I know I am thinking too much in C). I thought the global declaration would have been sufficient but it's obviously not. Thanks, -- http://mail.python.org/mailman/listinfo/python-list
Re: A scoping question
On Tue, 28 Dec 2004 19:34:36 GMT, It's me [EMAIL PROTECTED] wrote: This must be another newbie gotchas. Consider the following silly code, let say I have the following in file1.py: #= import file2 global myBaseClass myBaseClass = file2.BaseClass() myBaseClass.AddChild(file2.NextClass()) #= You have declared myBaseClass to be global, but it doesn't exist. Consider the following code: global name print name.__len__() This will return a NamError However, the following code will run just fine: global name name = python print name.__len__() will return 6 and in file2.py, I have: #= global myBaseClass class BaseClass: def __init__(self): self.MyChilds = [] ... def AddChild(NewChild): self.MyChilds.append(NewChild) ... class NextClass: def __init__(self): for eachChild in myBaseClass.MyChilds: # - ERROR ... #= When I run this, Python complains that myBaseClass is undefined in the last line above. What am I doing wrong? (Yes, I know I am thinking too much in C). I thought the global declaration would have been sufficient but it's obviously not. Thanks, -- http://mail.python.org/mailman/listinfo/python-list HTH -- Premshree Pillai http://www.livejournal.com/~premshree -- http://mail.python.org/mailman/listinfo/python-list
Re: A scoping question
Premshree Pillai [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] On Tue, 28 Dec 2004 19:34:36 GMT, It's me [EMAIL PROTECTED] wrote: This must be another newbie gotchas. Consider the following silly code, let say I have the following in file1.py: #= import file2 global myBaseClass myBaseClass = file2.BaseClass() myBaseClass.AddChild(file2.NextClass()) #= You have declared myBaseClass to be global, but it doesn't exist. No, myBaseClass exists in file1.py. The question is how can I tell file2.py that the global variable is in file1 (without doing a silly file1.myBaseClass Since I am invoking file2 from file1, I would have thought that global variables in file1 exists automatically(too much C thinking, I know) -- http://mail.python.org/mailman/listinfo/python-list
Re: Repainting
LutherRevisited wrote: I have an application that uses a WxListCtrl to hold data that is updated extremely fast. When I run my application the listctrl updates so fast that it practically disappears. Is there a way I can have it update with the user seeing it update rapidly without the dissapearing? Right now I have used the freeze and thaw methods to get rid of that disappearing listctrl problem, only now you have to wait for it to run it's course to see the output. It really isn't critical, I just think it would be a cool visual if the user could see it rapidly updating, I'm beginning to think that because of how rapidly it updates that isn't possible, but if it is I appreciate any help. And you guys would be so proud of me, I actually downloaded the Wx docs and found freeze and thaw all on my own under wxwindows memberslol. That's a quick note out to all that have been patient with me while helping me learn wxpython. Glad to see you downloaded the docs! Ok since you made some effort I will try again to help you. just do a search for wxYield. This is straight off the web. ''' ::wxYield Bool wxYield(void) Yields control to pending messages in the windowing system (has no effect under XView or Motif). This can be useful, for example, when a time-consuming process writes to a text window. Without an occasional yield, the text window will not be updated properly, and (since Windows multitasking is cooperative) other processes will not respond. Caution should be exercised, however, since yielding may allow the user to perform actions which are not compatible with the current task. Disabling menu items or whole menus during processing can avoid unwanted reentrance of code. ''' Just sprinkle your listctrl update loop with wx.Yield(). I am not sure if this will help you but has fixed update problems for me before. By the way when you have problems with wxPython you may get more responses from the wxPython list. Comp.lang.python is good for general python, but wxPython list is specific to the wx framework. hth, M.E.Farmer -- http://mail.python.org/mailman/listinfo/python-list
Re: A scoping question
On Tue, 28 Dec 2004 19:59:01 GMT, It's me [EMAIL PROTECTED] wrote: Premshree Pillai [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] On Tue, 28 Dec 2004 19:34:36 GMT, It's me [EMAIL PROTECTED] wrote: This must be another newbie gotchas. Consider the following silly code, let say I have the following in file1.py: #= import file2 global myBaseClass myBaseClass = file2.BaseClass() myBaseClass.AddChild(file2.NextClass()) #= You have declared myBaseClass to be global, but it doesn't exist. No, myBaseClass exists in file1.py. The question is how can I tell Umm, from the sample code (for file2.py) that you provided, I don't see myBaseClass. You've only declared it to be global in file2.py, but it does not exist -- does not exist in the sense that it has no type associated with it, which in turn means meaning you cannot apply methods to it. file2.py that the global variable is in file1 (without doing a silly file1.myBaseClass Since I am invoking file2 from file1, I would have thought that global variables in file1 exists automatically(too much C thinking, I know) -- http://mail.python.org/mailman/listinfo/python-list -- Premshree Pillai http://www.livejournal.com/~premshree -- http://mail.python.org/mailman/listinfo/python-list
Re: A scoping question
It's me wrote: This must be another newbie gotchas. Consider the following silly code, let say I have the following in file1.py: #= import file2 global myBaseClass myBaseClass = file2.BaseClass() myBaseClass.AddChild(file2.NextClass()) #= and in file2.py, I have: #= global myBaseClass class BaseClass: def __init__(self): self.MyChilds = [] ... def AddChild(NewChild): self.MyChilds.append(NewChild) ... class NextClass: def __init__(self): for eachChild in myBaseClass.MyChilds: # - ERROR ... #= When I run this, Python complains that myBaseClass is undefined in the last line above. What am I doing wrong? (Yes, I know I am thinking too much in C). I thought the global declaration would have been sufficient but it's obviously not. I think you're confused about what the global keword does. Declaring a name as global makes that name global *to the module*: http://docs.python.org/ref/global.html http://docs.python.org/lib/built-in-funcs.html#l2h-32 What you probably want instead is: file1.py import file2 myBaseClass = file2.BaseClass() myBaseClass.AddChild(file2.NextClass()) -- file2.py class BaseClass: def __init__(self): self.MyChilds = [] def AddChild(self, NewChild): self.MyChilds.append(NewChild) class NextClass: def __init__(self): from file1 import myBaseClass # IMPORT for eachChild in myBaseClass.MyChilds: pass -- Note that I import myBaseClass in __init__. If I imported it at the top of the module, then file1 would import file2 which would then import file1 and you'd have a circular dependency. As it is, your code is very tightly coupled. Why don't you put all this code into a single module? Steve -- http://mail.python.org/mailman/listinfo/python-list
Re: A scoping question
It's me wrote: This must be another newbie gotchas. Consider the following silly code [snip tightly coupled code] A few options that also might work better than such tightly coupled modules: file1.py import file2 myBaseClass = file2.BaseClass() class NextClass: def __init__(self): for eachChild in myBaseClass.MyChilds: pass myBaseClass.AddChild(file2.NextClass()) -- file2.py class BaseClass: def __init__(self): self.MyChilds = [] def AddChild(self, NewChild): self.MyChilds.append(NewChild) -- or file1.py import file2 myBaseClass = file2.BaseClass() myBaseClass.AddChild(file2.NextClass(myBaseClass)) -- file2.py class BaseClass: def __init__(self): self.MyChilds = [] def AddChild(self, NewChild): self.MyChilds.append(NewChild) class NextClass: def __init__(self, myBaseClass): for eachChild in myBaseClass.MyChilds: pass -- -- http://mail.python.org/mailman/listinfo/python-list
Re: pygame + py2exe = bad exe. why?
Hello Erik,
Have you ever seen pygame2exe.py?
It is a py2exe script for pygame.
I found this on my hard drive from last year.
I have never created an exe from pygame using this script , so it might
be useless ;)
Do a search might be updated by now.can not remember where I got it
from ( maybe pygame website? )
py#make standalone, needs at least pygame-1.5.3 and py2exe-0.3.1
pyfrom distutils.core import setup
pyimport sys, os, pygame, shutil
pyimport py2exe
py
py#setup the project variables here.
py#i can't claim these will cover all the cases
py#you need, but they seem to work for all my
py#projects, just change as neeeded.
py
py
pyscript = aliens.py#name of starting .PY
pyicon_file = #ICO file for the .EXE (not working
well)
pyoptimize = 2#0, 1, or 2; like -O and -OO
pydos_console = 1 #set to 0 for no dos shell when run
pyextra_data = ['data', 'readme.txt'] #extra files/dirs copied to game
pyextra_modules = ['pygame.locals'] #extra python modules not auto
found
py
py#use the default pygame icon, if none given
pyif not icon_file:
pypath = os.path.split(pygame.__file__)[0]
pyicon_file = '' + os.path.join(path, 'pygame.ico') + ''
py#unfortunately, this cool icon stuff doesn't work in current py2exe
:(
py#icon_file = ''
py
py
py#create the proper commandline args
pyargs = ['py2exe', '--force', '-O'+`optimize`]
pyargs.append(dos_console and '--console' or '--windows')
pyif icon_file:
pyargs.append('--icon')
pyargs.append(icon_file)
pyargs.append('--force-imports')
pyargs.append(','.join(extra_modules))
py#args.append(','.join(pygame_modules + extra_modules))
pysys.argv[1:] = args + sys.argv[1:]
py
pyproject_name = os.path.splitext(os.path.split(script)[1])[0]
py
py
py#this will create the executable and all dependencies
pysetup(name=project_name, scripts=[script])
py
py#also need to hand copy the extra files here
pydef installfile(name):
pydst = os.path.join('dist', project_name)
pyprint 'copying', name, '-', dst
pyif os.path.isdir(name):
pydst = os.path.join(dst, name)
pyif os.path.isdir(dst):
pyshutil.rmtree(dst)
pyshutil.copytree(name, dst)
pyelif os.path.isfile(name):
pyshutil.copy(name, dst)
pyelse:
pyprint 'Warning, %s not found' % name
py
py
py
py
pypygamedir = os.path.split(pygame.base.__file__)[0]
pyinstallfile(os.path.join(pygamedir,
pygame.font.get_default_font()))
pyinstallfile(os.path.join(pygamedir, 'pygame_icon.bmp'))
pyfor data in extra_data:
pyinstallfile(data)
This is probably a complete mess by the time it reaches you.
I started every line with py so just unwrap the lines that didn't make
it.
Hth,
M.E.Farmer
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Re: Best GUI for small-scale accounting app?
On Dec 28, 2004, at 1:16 PM, Paul Rubin wrote: Well, those are commercial developers who are afraid of the GPL. No, they were several members of the Python community. I disagreed with their interpretation of the GPL, but the fact remains that it was a major stumbling block to getting others involved. I don't see how you lose with the GPL, unless you count missing out on the exciting opportunity to be an unpaid employee of someone else's corporation, without even getting back improvements made to your code. The downside is gaining critical mass for the project. Having several visible Python folks refuse to even look at what we were doing was not helping things at all. And I think it the chances of someone else using my code without payment or anything is a pretty small risk. We still own copyright, which means that while they can use it, they can't claim it's theirs. I'm not sure what sizers are OIC - then this is not going to be very fruitful. Ehhh, sounds a little too much like javabeans :). No, it sounds like every other development environment for creating database applications. I looked a long time for something like this in Python before undertaking the writing of it myself. ___/ / __/ / / Ed Leafe http://leafe.com/ http://dabodev.com/ -- http://mail.python.org/mailman/listinfo/python-list
Re: HELP Non-Blocking reads from sys.stdin in Windows.
Hello Barr, I am in real need of a way to perform non blocking reads from sys.stdin on windows. I have looked every where for an answer but but with no luck. I beleive there there must be a way of doing this, can some one please help asap. Warning: The below code wasn't tested at all... --- from Queue import Queue, Empty from sys import stdin from threading import Thread # Reading from empty stdin error class EmptyError(Exception): pass # Input queue _queue = Queue() def produce(): '''Read one char at a time from stdin and place in _queue''' try: while 1: c = stdin.read(1) # Read one char if not c: # EOF _queue.put(EOFError, 1) break _queue.put(c, 1) except EOFError, e: _queue.put(EOFError) # Start the thread t = Thread(target=produce) t.setDaemon(1) # Don't inhibit interperter exit t.start() # Start thread def get(): '''Get one item from queue. Might raise EmptyError if queue is empty or EOFError of end of input ''' try: val = _queue.get(0) if val is EOFError: raise EOFError return val except Empty: raise EmptyError def is_empty(): '''Tell if no input is ready''' return _queue.empty() --- HTH. -- Miki Tebeka [EMAIL PROTECTED] http://tebeka.bizhat.com The only difference between children and adults is the price of the toys -- http://mail.python.org/mailman/listinfo/python-list
naming conventions (WAS: A scoping question)
It's me wrote: #= import file2 global myBaseClass myBaseClass = file2.BaseClass() myBaseClass.AddChild(file2.NextClass()) #= [snip] #= global myBaseClass class BaseClass: def __init__(self): self.MyChilds = [] ... def AddChild(NewChild): self.MyChilds.append(NewChild) ... class NextClass: def __init__(self): for eachChild in myBaseClass.MyChilds: # - ERROR ... #= Also worth mentioning if you're just starting with Python. Python has some official naming conventions: http://www.python.org/peps/pep-0008.html These are just recommendations of course, but if you have the option (e.g. you're not constrained by style enforced by your employer), and you'd like your code to look more like standard Python modules, you might consider using these suggestions. This would make your code look something like: #= import file2 global my_base_class my_base_class = file2.BaseClass() my_base_class.add_child(file2.NextClass()) #= #= global my_base_class class BaseClass: def __init__(self): self.my_childs = [] ... def add_child(new_child): self.my_childs.append(new_child) ... class NextClass: def __init__(self): for each_child in my_base_class.my_childs: # - ERROR ... #= Steve -- http://mail.python.org/mailman/listinfo/python-list
Re: Tkinter vs wxPython
Cameron Laird wrote: IMO, wxPython has a softert learning curve (specially if you use wxGlade), is portable between unix/windows/mac, with the advantage over Tkinter that it has a native look. Regarding documentation, . While people seem to mean a range of different things when they write, Tkinter doesn't look 'native', most of them are being addressed in revisions currently underway. In fact, new look- and-feel are available in early releases for those interested in experimentation. Well, while on Windows native look exists, on X11 native has other meaning. On my wife's desktop it's KDE that is native, GNUStep is native on mine and I strongly object calling GTK native, as one can read on SWT/Eclipse website. There's no universally native look on X11. Some toolkits look better, but this is a matter of personal taste, for software developer clean, stable API and suitable widgets are of much higher value. -- Jarek Zgoda http://jpa.berlios.de/ | http://www.zgodowie.org/ -- http://mail.python.org/mailman/listinfo/python-list
install questions
Hi, All,
I'm new in Python. I just install ActivePython 2.4 on
my PC and also install SOAPpy-0.11.6.zip,
soapy-0.1.win32.exe. When I run the following script,
I got no module named SOAPpy. Am I missing any
modules? Thanks
Angela
error message:
Traceback (most recent call last):
File
C:\Python24\Lib\site-packages\pythonwin\pywin\framework\scriptutils.py,
line 310, in RunScript
exec codeObject in __main__.__dict__
File C:\test1.py, line 1, in ?
import SOAPpy
ImportError: No module named SOAPpy
=
Python script:
import SOAPpy
WSDL_URI =
http://www.xmethods.net/sd/2001/TemperatureService.wsdl;
service = SOAPpy.WSDL.Proxy(WSDL_URI)
# if you are behind a proxy server, you need to set
this
service.soapproxy.http_proxy = 'PROXY_HOST:PROXY_PORT'
# set config so that we dump the SOAP envelopes
# (sometimes you will be thrilled to see the SOAP
envelopes)
service.soapproxy.config.dumpSOAPOut = 1
service.soapproxy.config.dumpSOAPIn = 1
temp = service.getTemp('90210') # get temperature in
Beverly Hills
print 'The temperature in Beverly Hills is',temp,'F'
===
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Re: install questions
Umm, the file is called soap.py, so when you import you'll have to do a:
import soap
On Tue, 28 Dec 2004 13:09:48 -0800 (PST), A Chan [EMAIL PROTECTED] wrote:
Hi, All,
I'm new in Python. I just install ActivePython 2.4 on
my PC and also install SOAPpy-0.11.6.zip,
soapy-0.1.win32.exe. When I run the following script,
I got no module named SOAPpy. Am I missing any
modules? Thanks
Angela
error message:
Traceback (most recent call last):
File
C:\Python24\Lib\site-packages\pythonwin\pywin\framework\scriptutils.py,
line 310, in RunScript
exec codeObject in __main__.__dict__
File C:\test1.py, line 1, in ?
import SOAPpy
ImportError: No module named SOAPpy
=
Python script:
import SOAPpy
WSDL_URI =
http://www.xmethods.net/sd/2001/TemperatureService.wsdl;
service = SOAPpy.WSDL.Proxy(WSDL_URI)
# if you are behind a proxy server, you need to set
this
service.soapproxy.http_proxy = 'PROXY_HOST:PROXY_PORT'
# set config so that we dump the SOAP envelopes
# (sometimes you will be thrilled to see the SOAP
envelopes)
service.soapproxy.config.dumpSOAPOut = 1
service.soapproxy.config.dumpSOAPIn = 1
temp = service.getTemp('90210') # get temperature in
Beverly Hills
print 'The temperature in Beverly Hills is',temp,'F'
===
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http://www.livejournal.com/~premshree
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Re: Reference behavior through C (was: Lambda going out of fashion)
On Wed, 2004-12-29 at 02:08, Cameron Laird wrote: In article [EMAIL PROTECTED], Craig Ringer [EMAIL PROTECTED] wrote: . . . IMO the reference behaviour of functions in the C API could be clearer. [snip] . . . This is a sensitive area for me, too. I'd welcome insight on how to think about this. If Pythonia were a better place in this regard, how would it be? Reference documents that more transparently define reference behavior? I think the current documentation does a fairly good job of that when describing how to treat the return values of the various functions, but a much poorer one when covering their arguments. A convention for API names that reveals reference characteristics? That is what I'd lean towards personally... but of course there's duplication and compatibility to be considered. -- Craig Ringer -- http://mail.python.org/mailman/listinfo/python-list
RE: built-in 'property'
Title: RE: built-in 'property'
Thanks to everyone that has helped on this. What I am trying to do is create a capability based api that I can build to order. This is as far as I get at the moment.
Each of the first three classes represents some function I can do to a radio, there would be many of these in practice. The next class is the API. I figure I have to include all the possible radio function classes in this as I can't figure out how to make the classes I include per instance. When I create the API object I pass in a capability array as in the last class. I use these classes as follows.
import capability as c
import radioapi as r
caps = c.Capability()
cap = caps.getCaps('SDR1000')
cap
['mode', 'freq', 'blanker']
api = r.API(cap)
r.caps
['mode', 'freq', 'blanker']
api.mode
Retrieving mode var mode
'lsb'
api.freq
Retrieving freq var freq
7.0801
api.blanker
Retrieving blanker var blanker
1
hasattr(api, 'monitor')
0
This is the behaviour I want, each class responds if it is in the capability array. The user can test attributes with hasattr(klass, 'att') to see if it is supported. I can create another instance with a different radio and it will respond accordingly. The problem of course is that in class API, caps is global so as soon as I create another instance the first starts responding to the new capability. If I try to make caps per instance I get into all sorts of trouble with recursion. Does anyone have an idea how to fix this or is it just impossible to make this work.
Regards
Bob
class Mode(object):
def __init__(self, initval=None, name='var'):
self.val = initval
self.name = name
def __get__(self, obj, objtype):
print 'Retrieving mode', self.name
return self.val
def __set__(self, obj, val):
print 'Updating mode' , self.name
self.val = val
import capability
class Freq(object):
def __init__(self, initval=None, name='var'):
self.val = initval
self.name = name
def __get__(self, obj, objtype):
print 'Retrieving freq', self.name
return self.val
def __set__(self, obj, val):
print 'Updating freq' , self.name
self.val = val
class Blanker(object):
def __init__(self, initval=None, name='var'):
self.val = initval
self.name = name
def __get__(self, obj, objtype):
print 'Retrieving blanker', self.name
return self.val
def __set__(self, obj, val):
print 'Updating blanker' , self.name
self.val = val
class API(object):
# create all possible radio classes
mode=Mode('lsb', 'var mode')
freq=Freq(7.080, 'var freq')
blanker=Blanker(True, 'var blanker')
global caps
caps = []
def __init__(self, pcaps):
global caps
caps = pcaps
def __getattribute__(self, key):
global caps
if (key in caps) or (key == 'caps'):
obj = object.__getattribute__(self, key)
if hasattr(obj, __get__):
return obj.__get__()
return obj
else:
raise AttributeError, unreadable attribute
class Capability(object):
m_cap = {
'SDR1000': ['mode','freq','blanker'],
'MyRig': ['mode','freq'],
'YourRig': ['mode', 'blanker']
}
def getCaps(self, radio):
return self.m_cap[radio]
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Re: Mutable objects which define __hash__ (was Re: Why are tuples immutable?)
On Sun, 26 Dec 2004 12:17:42 +1000, Nick Coghlan [EMAIL PROTECTED] wrote: Bengt Richter wrote: I take it you are referring to regular python dictionaries, Correct. So I'll skip over the sections talking about alternate lookup strategies in my reply. Cool. Anyway, what are the consequences of a type which has a 'variable hash'? The only real bad consequence is that the internal state of a dictionary can break if someone alters the hash of one of its keys. The restriction to 'constant hashes' is aimed squarely at eliminating this class of programming errors. It doesn't actually provide any performance gain. Why not? It means you only have to compute the hash for any given object once, and you can cache the hash value. That could be a biggie if you had megabyte trees of nested tuples as keys and reused them frequently for lookup. Allowing mutation doesn't mean abandoning your caching - it just means you need a way to tell the dict to update it's key cache (i.e. rehash()) There's more than one way a key gets hashed: once when the key:value association is entered into the dict state. (It pays to save the hash value in the dict along with references to the key and value objects for several reasons, which I'll get to [1]). A second time a key may be hashed is when it is used as a lookup key. This can be a reference to the identical key object first used, or it can be a new object. A new object has to be hashed in order to have a hash value to use in finding candidate keys to compare to. If _this_ object is used as a key again, it must be hashed again -- unless it is an object that caches its own hash and invalidates it when mutated so it can rehash itself if its __hash__ method is subsequently called. Thus re-use of a different lookup key than the original provides an opportunity for a performance gain in the lookup if the key object caches it hash value for return by __hash__. That's what I meant by why not? in response to your assertion that the constant hash restriction doesn't (ok, I took that as a can't ;-) provide any performance gain. [1] IME a hash is only necessary to optimize operation of a dict. The primary purpose is to limit the number of comparisons necessary to determine whether a key exists in the dict, and to find the matching one. First the hash value is converted to a bucket selection. This will involve some function of the full hash value, reducing it to a value that can access buckets. This function can potentially change as the dict grows. Once the bucket is selected, a number of keys may be found there. Since thejob is to find equality, the hash value can serve again, using all its bits, to select a subset of the keys in the bucket that _may_ be equivalent. This is an optimization to avoid comparing key objects with differing hashes -- which is fine for immutable keys, which can't be the same if their hashes differ. IOW, immutable key candidates may be rejected immediately if their hash values aren't equal to the lookup key's hash value. The other side of this coin is that keys whose hash values _are_ equal to the lookup key's hash value must all be compared in some order (probably whatever order is convenient in working through a bucket) until an equal key is found, or not. This means that if we give all mutable keys the same hash value, they will all be in the same bucket, and that bucket will be searched in some order for an equal key, and the first one found to be equal will be what I called the effective unique key. With a constant hash value -- e.g., zero -- there is no reason to re-hash: the hashes haven't changed ;-) There may be a reason to eliminate shadowed keys with duplicate equal values, but it's not necessary for consistent operation. Based on this, I made a wrapper object for mutable keys, which returns a constant zero as the hash value, and provides a __cmp__ of the wrapped object for the dict's key equality testing. This means if W is the wrapper class, you can use W(mutable) as a key in an ordinary dict, and they all go to the same bucket as 0 and 0.0 and whatever else hashes to 0. I decided to modify my dict subclass to wrap unhashable key objects automatically, with very similar effect to the original, except eliminating the parallel lists for the mutable keys and their values. The only thing is that I knew the order of list.index searching, but I don't know the order of bucket 0 searching, so shadowing and elimination of duplicate keys by re-instantiation will probably eliminate different duplicates sometimes. I think, for one thing, it would be more efficient to notice that some keys were guaranteed not to need rehashing... um, maybe by paritioning the key set into immutables and mutables ;-) True, since otherwise rehash() would have to check every key, even the immutable ones. However, that only affects the time required for a rehash(), rather than general dictionary operation. Given that you
Problems installing MySQLdb on Windows [newbie]
hi, all! this is my first contact with python, I installed python 2.4 (on Win2k) and unzipped the MySQLdb package MySQL-Python 1.0.0 for win32 into Lib/site-packages. However, when I try to import the MySQLdb package, I am faced with the error message DLL load failed, in more detail: import MySQLdb Traceback (most recent call last): File pyshell#9, line 1, in -toplevel- import MySQLdb File C:\Programme\Python24\lib\site-packages\MySQLdb\__init__.py, line 27, in -toplevel- import _mysql ImportError: DLL load failed: Das angegebene Modul wurde nicht gefunden. The directory structure is (only the relevant parts): C:\Programme\Python24 | +-- Lib | +-- site-packages | +-- _mysql.pyd +-- _mysql_exceptions.py +-- CompatMysqldb.py +-- MySQLdb | +-- __init__.py +-- connections.py +-- ... One thing strikes me: in sys.path, the path to site-packages contains the dir lib (lowercase!) whereas in the file system it would be written Lib (mixed case). Could this pose a problem? This is the path: sys.path ['C:\\Programme\\Python24\\Lib\\idlelib', 'C:\\WINNT\\system32 \\python24.zip', 'C:\\Programme\\Python24', 'C:\\Programme\\Python24 \\DLLs', 'C:\\Programme\\Python24\\lib', 'C:\\Programme\\Python24\\lib \\plat-win', 'C:\\Programme\\Python24\\lib\\lib-tk', 'C:\\Programme \\Python24\\lib\\site-packages'] Any hints for me? TIA Alex -- remove underscore+nospam if you want to mail me -- http://mail.python.org/mailman/listinfo/python-list
Re: argument type
It's me [EMAIL PROTECTED] wrote: How can I tell from within a function whether a particular argument is a sigular type, or a complex type? ... In C++, you would do it with function overloading. If arg1 is always simple type, I wouldn't care what it is. But what if I *do* need to know whether arg1 is a list or not? I have a vague feeling you're trying to write C++ in Python, and that usually doesn't work well. In general, C++ (and Java) is all about types of things, while Python is more about capabilities of things. What do you mean by a simple type as opposed to a complex type? I suspect by complex type you really mean tuple or list. If that's the case, you can certainly do something like: def myFunc (arg): if isinstance (arg, tuple) or isinstance (arg, list): blah, blah, blah But before you do that, you might want to think if this is really what you want to do. What, exactly, is it that you're trying to do that requires you to know what type of object an argument is? -- http://mail.python.org/mailman/listinfo/python-list
Re: objects as mutable dictionary keys
I think that's a good summary. The condensed version is that the results of both __hash__() and __cmp__() have to remain stable for dicts to work as one would expect. __cmp__ doesn't do that for lists, and it isn't defined by default for user objects. John Roth Peter Maas [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] Peter Maas schrieb: There was a huge and sometimes heated debate about tuples, lists and dictionaries recently, and the mainstream opinion was that dictionary keys must not be mutable, so lists are not allowed as dictionary keys. Warning, long posting (~ 100 lines) The existence of lists and tuples and the impossibility to use lists as dictionary keys is a constant source of irritation for Python newcomers. Recent threads in c.l.py have revealed that even programmers like me using Python for some years now often don't have a clear picture. To put an end to this misery I tried to learn from the recent discussions and to explain to myself what's going on. My problem was that I didn't know exactly how a dictionary and a dictionary lookup works: A dictionary maps key values to data values. Sketch of a dictionary lookup(value = dict[key]): def lookup(dict, key): '''dictionary lookup is done in three steps: 1. A hash value of the key is computed using a hash function. Hash functions map a large set L to a (usually) smaller set S. A hash function must satisfy: (*) for all e1, e2 in L: h(e1) != h(e2) = e1 != e2 A hash function should satisfy as well as possible: for all e1, e2 in L: h(e1) == h(e2) = e1 == e2 Violation of the latter condition means a hash collision, i.e. two or more elements of L have the same hash value. This should be highly unlikely for good hash functions. If not, hash lookup becomes as slow as sequential lookup. 2. The hash value addresses a location in dict.data which is supposed to be an array of bins. A bin contains a collision list of (key,value) pairs. 3. The collision list addressed by the hash value is searched sequentially until a pair is found with pair[0] == key. The return value of the lookup is then pair[1]. Equality (==) is defined by the function cmp(). The return value for equality is 0, for inequality some other value. ''' h = hash(key) # step 1 cl = dict.data[h] # step 2 for pair in cl:# step 3 if cmp(key, pair[0]) == 0: return pair[1] else: raise KeyError, Key %s not found. % key Thus a data type must be a valid input for hash() and cmp() to be usable as a dictionary key. hash() and cmp() must satisfy the condition (*) in lookup.__doc__ for this data type. Is a list a suitable candidate for a dictionary key? hash(list) = id(list) and cmp(list1, list2) comparing id(list1) with id(list2) would satisfy condition (*). But this definition completely ignores list contents, causing big surprises for programmers: - Different lists with the same content would be mapped to different dictionary values. - Dictionary lookup with list literals would be impossible. To avoid these surprises dictionary lookup would have to use list contents instead of list id. Consider the (hypothetical, not working) code: d = dict() li = [1,2,3] d[li] = 123 d[[1,2,3]] 123 Now assume li is changed (e.g. li[2] = 4). There are two options to handle this, let the dictionary ignore changes d[li] KeyError: [1,2,4] not found in dictionary. (even worse: a previously existing [1,2,4] map is returned). or let the dictionary follow changes d[[1,2,3]] MovedError: Please address future lookups to [1,2,4] :) Both are pretty unsatisfactory. Conclusion: dictionary lookup with mutable types like lists is a source of unpleasant surprises for the programmer and therefore impossible in Python. This is the point where tuples come in. They have nearly the same interface as lists but cannot be changed once they have been created thereby avoiding the problems discussed for lists. Thus tuples can be used as dictionary keys. What about instances of user defined classes? User defined classes can be anything the programmer likes but yet their instances are usable as dictionary keys because there is a default: hash(object) = id(object) and cmp(object1, object2) compares id(object1) with id(object2). The same setting that has been discussed above for lists and has been found unsatisfactory. What is different here? 1. It is a default setting which can be adapted to each class by defining/ overriding the methods __hash__ and __cmp__. 2. For objects identity is more important than for lists. That's it. Please correct me if I'm wrong. If not, a poor programmer's soul has found peace eventually :) -- --- Peter Maas, M+R Infosysteme, D-52070 Aachen, Tel
Re: Problems installing MySQLdb on Windows [newbie]
Alex Meier wrote: hi, all! this is my first contact with python, I installed python 2.4 (on Win2k) and unzipped the MySQLdb package MySQL-Python 1.0.0 for win32 into Lib/site-packages. However, when I try to import the MySQLdb package, I am faced with the error message DLL load failed, in more detail: import MySQLdb Traceback (most recent call last): File pyshell#9, line 1, in -toplevel- import MySQLdb File C:\Programme\Python24\lib\site-packages\MySQLdb\__init__.py, line 27, in -toplevel- import _mysql ImportError: DLL load failed: Das angegebene Modul wurde nicht gefunden. The directory structure is (only the relevant parts): C:\Programme\Python24 | +-- Lib | +-- site-packages | +-- _mysql.pyd +-- _mysql_exceptions.py +-- CompatMysqldb.py +-- MySQLdb | +-- __init__.py +-- connections.py +-- ... One thing strikes me: in sys.path, the path to site-packages contains the dir lib (lowercase!) whereas in the file system it would be written Lib (mixed case). Could this pose a problem? No, Windows file lookups are not case-sensitive. This is the path: sys.path ['C:\\Programme\\Python24\\Lib\\idlelib', 'C:\\WINNT\\system32 \\python24.zip', 'C:\\Programme\\Python24', 'C:\\Programme\\Python24 \\DLLs', 'C:\\Programme\\Python24\\lib', 'C:\\Programme\\Python24\\lib \\plat-win', 'C:\\Programme\\Python24\\lib\\lib-tk', 'C:\\Programme \\Python24\\lib\\site-packages'] Any hints for me? TIA Alex I'm not sure that the Win32 installer is up to date for 2.4. I recently mailed Andy Dustman with a copy of the up to date installer I built, but I never had any acknowledgment and it doesn't appear to have found its way on to SourceForge yet. I'd suggest you use a binary installer. Remove everything that your current install attempt dropped under site-packages, and download and run http://pydish.holdenweb.com/pwp/MySQL-python.exe-1.0.0.win32-py2.4.exe That's a ready-to-go no-compilation-required installer for Windows Python 2.4, and will get you going straight away. regards Steve -- Steve Holden http://www.holdenweb.com/ Python Web Programming http://pydish.holdenweb.com/ Holden Web LLC +1 703 861 4237 +1 800 494 3119 -- http://mail.python.org/mailman/listinfo/python-list
Re: argument type
It's me wrote: The argument I wish to pass is either one string, or a list of strings, or a tuple of strings. For instance, I have: def abc(arg1, arg2, arg3) Let say that I expect arg1 and arg3 to be a number, and arg2 can be either one string, or a bunch of strings and I need to do something on each of the strings passed down. def seq(x): if hasattr(x,__iter__): return x else: return (x,) def abc (arg1, arg2, arg3): for item in seq(arg2): print item abc(1,test1,2) abc(1,[test1,test2],2) abc(1,2,3) abc(1,[2,3,4],5) abc(1,(2,3,4),5) -- http://mail.python.org/mailman/listinfo/python-list
Re: Best GUI for small-scale accounting app?
Ed Leafe schreef: I think the field of GUI frameworks / tools for Python is fragmented because it's fragmented outside of Python too... I think that the reason things are fragmented in this field is that none of the tools are simple enough to learn. Even on Windows, where several well-known and/or easy to use Rapid GUI Database Development Tools exist (Delphi, VB, Access, Visual FoxPro, FileMaker, ...), the framework field is fragmented: Microsoft's Win32, MFC WTL, Borland's VCL CLX, wxWidgets, System.Windows.Forms, several Java frameworks, ... But even then, if DaBo ever becomes as easy to use as Delphi/VB for this type of applications, while remaining cross-platform, that might easily double the number of Python developers. ;-) -- JanC Be strict when sending and tolerant when receiving. RFC 1958 - Architectural Principles of the Internet - section 3.9 -- http://mail.python.org/mailman/listinfo/python-list
Re: Problems installing MySQLdb on Windows [newbie]
Alex Meier wrote: hi, all! this is my first contact with python, I installed python 2.4 (on Win2k) and unzipped the MySQLdb package MySQL-Python 1.0.0 for win32 into Lib/site-packages. However, when I try to import the MySQLdb package, I am faced with the error message DLL load failed, in more detail: (1) RTFHomePage (FIRST SENTENCE): MySQL versions 3.22, 3.23 and 4.0; and Python versions 1.5.2-2.3 are supported. Background: A .pyd has to be linked against a specific PythonXY.dll; see point (4) below. (2) A package which doesn't provide an installer but merely invites you to unzip everything into .../lib/site-packages is a bit dodgy. If you had have followed the instructions blindly, you would have ended up with a directory called mysql-python-1.0.0.win32-py2.3 [, look, 2.3] as a child of site-packages. (3) Lib versus lib is not the problem; if you examine your traceback, you will see that it found Lib even though lib was specified. Windows file names are not case-sensitive. However there can be Python-imposed problems which can be overcome (in the remote event that you meet these problems) by using the PYTHONCASEOK environment veriable. (4) Why you are getting the DLL not found message is beyond me, given your description of what you've done. Perhaps the picture is being obscured by your using pyshell. What you should have got is something like this [I've extracted _mysql.pyd into my junk directory]: C:\junkpython Python 2.4 (#60, Nov 30 2004, 11:49:19) [MSC v.1310 32 bit (Intel)] on win32 Type help, copyright, credits or license for more information. import _mysql Traceback (most recent call last): File stdin, line 1, in ? ImportError: Module use of python23.dll conflicts with this version of Python. (5) But the _mysql.pyd appears to be a bit suspect anyway: C:\junk\python23\python Python 2.3.4 (#53, May 25 2004, 21:17:02) [MSC v.1200 32 bit (Intel)] on win32 Type help, copyright, credits or license for more information. import _mysql Traceback (most recent call last): File stdin, line 1, in ? ImportError: _mysql: init failed (6) I suggest that you contact the package maintainer. -- http://mail.python.org/mailman/listinfo/python-list
Re: emulating python shell
Uwe Mayer wrote: Hi, in an application I want to provide direct access to the python interpreter of the running program. I use rawinput() and exec() to read an input string and a self-made function to check wether the inputed block is closed and then execute it. When running python interactively the result of the previous statement is assigned to the variable _ and commands like dir() just output their results to stdout. However, executions of the sort: exec(_ = +command) don't work. Any ideas how to mimick python -i 's behaviour? You can look at the code.py module in the python standard lib. It implements a pure-python interactive interpreter from scratch, so there's no need for you to reinvent that particular wheel. Since it's in the standard lib, you can rely on it for deployment to external sites. plug If you want something more sophisticated, and ready-made for this kind of embedding, look at ipython: http://ipython.scipy.org. IPython is itself based on code.InteractiveConsole, but at this point it has overridden almost all of the methods in the base class. Embedding it is as easy as: from IPython.Shell import IPShellEmbed ipshell = IPShellEmbed() ipshell() # this call anywhere in your program will start IPython You can have multiple embedded instances, and they can be initialized to use anythingb You can find further details about embedding ipython here: http://ipython.scipy.org/doc/manual/node9.html /plug HTH, f -- http://mail.python.org/mailman/listinfo/python-list
ImportError and jythonc
I have a Jython script that uses Java classes and runs fine using jython. It also compiles using jythonc. However, when I try to run the compiled program with the same CLASSPATH, I get an ImportError upon first Java import. How can I fix this? -- Henri Sivonen [EMAIL PROTECTED] http://iki.fi/hsivonen/ -- http://mail.python.org/mailman/listinfo/python-list
Convert all images to JPEG
Hi, I got a bunch of different images of different types ( bmp, gif, png, tiff etc ) and I want to convert them all to JPEGs using PIL. Is this possible? When I try I get all sorts of errors, doing something like : im = Image.open(srcImage) # might be png, gif etc, for instance test1.png im.thumbnail(size, Image.ANTIALIAS) # size is 640x480 im.save(targetName, JPEG) # targetname is test1.jpg produces an exception. Any clues? Best regards, Thomas -- http://mail.python.org/mailman/listinfo/python-list
Re: Problems installing MySQLdb on Windows [newbie]
In article [EMAIL PROTECTED], [EMAIL PROTECTED] says... http://pydish.holdenweb.com/pwp/MySQL-python.exe-1.0.0.win32-py2.4.exe That's a ready-to-go no-compilation-required installer for Windows Python 2.4, and will get you going straight away. Thanx a lot, Steve! This worked without a hitch. Alex -- remove underscore+nospam if you want to mail me -- http://mail.python.org/mailman/listinfo/python-list
Re: list addition methods compared.
On Mon, 27 Dec 2004 18:49:14 +0100, François Granger [EMAIL PROTECTED] wrote: Le 27/12/04 1:03, « Ishwor » [EMAIL PROTECTED] a écrit : so indeed method 2 (l2.extend() ) is the fastest ?? In 2/3 times, method 3 (l3 += [x] seems faster than method 1/2 in my P2.4GHZ machine with 512mb??? :-( Could u run the code in your machine and perhaps and let me know what the average speed is?? On a iBook G4 à 1.2 Ghz loaded with tons of other softwares running. fgranger:/develop/python scripts fgranger$ python listspeed.py @@@ Method 1 done in (average finish time(out of 3)) - 5.6365475655 Method 2 done in (average finish time(out of 3)) - 0.0562076569 Method 3 done in (average finish time(out of 3)) - 0.0455052853 @@@ fgranger:/develop/python scripts fgranger$ python listspeed.py @@@ Method 1 done in (average finish time(out of 3)) - 6.1534483433 Method 2 done in (average finish time(out of 3)) - 0.0637686253 Method 3 done in (average finish time(out of 3)) - 0.0500767231 @@@ fgranger:/develop/python scripts fgranger$ python listspeed.py @@@ Method 1 done in (average finish time(out of 3)) - 5.5850391388 Method 2 done in (average finish time(out of 3)) - 0.0594174862 Method 3 done in (average finish time(out of 3)) - 0.0549054146 @@@ Thank you. ;-) method 3 ( l += [x] which maps to l.extend([x]) ) indeed seems fastest. well anyway i'll be using timeit module from now onwards as Steve pointed out. Thank you. [snip] -- On a cold day please heat your laptop using while 1: pass ;-) cheers, Ishwor Gurung -- http://mail.python.org/mailman/listinfo/python-list
Re: Problems installing MySQLdb on Windows [newbie]
[EMAIL PROTECTED] says... (1) RTFHomePage (FIRST SENTENCE): MySQL versions 3.22, 3.23 and 4.0; and Python versions 1.5.2-2.3 are supported. I have to admit I took a chance because the error message led me to thinking it was a simple path problem or the like, not a version problem. Anyway, I got the whole thing up and running using the binary installer Steve has pointed me to. So my interest in finding out what really had happened has decreased somewhat - to say the least. Nevertheless, thank you for your extensive answer, Alex -- remove underscore+nospam if you want to mail me -- http://mail.python.org/mailman/listinfo/python-list
Re: Q: Scheduling in scipy.cow
Scott David Daniels wrote: Mathias wrote: Dear NG, can somebody tell me how the work packages are scheduled to the workers? From the code it seems to me like a a static distribution, ie each worker gets the same amount of work, not taking into account if a faster worker already finished all work packages. Thanks, Mathias PS: Is there a better NG for scipy related questions, espescially scipy.cow? I don't know the general newsgroup name, but: gmane.comp.python.scientific.user or gmane.comp.python.scientific.devel on news.gmane.org are the places I watch for scipy stuff. These are the gmane interfaces to the scipy user/dev lists, which can be found here in regular mailing list form: http://www.scipy.org/mailinglists/ Cheers, f -- http://mail.python.org/mailman/listinfo/python-list
Re: Convert all images to JPEG
Thomas wrote:
im = Image.open(srcImage) # might be png, gif etc, for instance
test1.png
im.thumbnail(size, Image.ANTIALIAS) # size is 640x480
im.save(targetName, JPEG) # targetname is test1.jpg
produces an exception. Any clues?
The problem is that test1.png is a paletted image, and JPEGs can only
hold true-color images. Try changing the last line to:
im.convert('RGB').save(targetName, 'JPEG')
--
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Re: More elegant way to cwd?
For library modules there are already other and more elegant means. -Peter Well, I want to make a script execute without error regardless of where the current working directory is, and without having to make the user modify their PYTHONPATH variable or install something in site-packages. Is there a way to let the user just 'drag the folder' anywhere on their hard drive, and have it work, without having to modify any special system variables? -- http://mail.python.org/mailman/listinfo/python-list
Re: Tkinter vs wxPython
Definitely look at PyQt. It was the GUI framework I chose when going through the same process 3 weeks ago. I have to disagree with F.Geiger (sorry, F.Geiger), I think a GUI builder is a necessity. It saves you a lot of time. The alternative is to keep changing your code until your GUI looks as you want. With a GUI builder you draw what you want and have the tool generate the Python class for the GUI. It also sets up event handlers for you too. Visual elements are best designed visually!!! -- http://mail.python.org/mailman/listinfo/python-list
Re: Best GUI for small-scale accounting app?
On Dec 28, 2004, at 5:52 PM, JanC wrote: But even then, if DaBo ever becomes as easy to use as Delphi/VB for this type of applications, while remaining cross-platform, that might easily double the number of Python developers. ;-) Well, there are at least a half-million Visual FoxPro developers who have been hung out to dry by Microsoft, most of whom would love to leave the land of proprietary closed solutions for a bit of fresh air. That's where Paul and I came from, and that was our initial motivation for deciding to develop Dabo - there wasn't a Python tool out there that could even begin to approach what we were used to with VFP. If we could get Dabo to the point where someone familiar with VFP or even VB could become productive in a short time, well, I'm certain that there will be lots of new blood in these parts. Our work is being followed very closely by those communities. ___/ / __/ / / Ed Leafe http://leafe.com/ http://dabodev.com/ -- http://mail.python.org/mailman/listinfo/python-list
getattr() woes
Hello
I've found out about a fundamental problem of attribute lookup, the
hard way.
asyncore.py uses the following code:
class dispatcher:
# ...
def __getattr__(self, attr):
return getattr(self.socket, attr)
Now suppose that I'm asking for some attribute not provided by
dispatcher: The lookup mechanism will apparently try to find it
directly and fail, generating an AttributeError; next it will call
__getattr__ to find the attribute. So far, no problems.
But I used a property much like this:
import asyncore
class Peer(asyncore.dispatcher):
... def _get_foo(self):
... # caused by a bug, several stack levels deeper
... raise AttributeError('hidden!')
... foo = property(_get_foo)
...
and as the error message suggests, the original AttributeError is
hidden by the lookup mechanism:
Peer().foo
Traceback (most recent call last):
File stdin, line 1, in ?
File /usr/lib/python2.4/asyncore.py, line 366, in __getattr__
return getattr(self.socket, attr)
AttributeError: 'NoneType' object has no attribute 'foo'
Is there anything that can be done about this? If there are no better
solutions, perhaps the documentation for property() could point out
this pitfall?
- Thomas
--
If you want to reply by mail, substitute my first and last name for
'foo' and 'bar', respectively, and remove '.invalid'.
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Re: Best GUI for small-scale accounting app?
On Dec 28, 2004, at 9:04 PM, Luke Skywalker wrote: Interesting discussion. I haven't looked at Dabo yet, but the issues that must be solved before Python is a valid alternative to proprietary solutions like Delphi or VB are: - speed where it matters (ie. no 20s load time) Load what? The app, or the data? Users don't care how long the app takes to start up, since they usually run it all day long. Data response is a whole 'nother matter, and Dabo is extremely fast in that regard. After all, a data set is nothing more than lists of lists, and Python is wicked fast with list handling. - good RAD (IDE and GUI designer, on par with Delphi or VB) Still in its infancy in Dabo. Would be nice to have a team working on it, cos there's only so much a single developer who also has a life can do. - high-quality, varied widgets One of the main reason we picked wxPython as our initial toolkit. Nearly everything we could want is in there, and they look good on all platforms. - good DB connectors That's not something we control. Dabo is designed to use existing dbapi-compliant connectors, such as MySQLdb. We currently support MySQL, PostgreSQL, and Firebird. If anyone has a need to link to another db, the script to do it is pretty well abstracted. - reasonable footprint (ie. no 20MB program just for a small appplication; have mercy on users stuck with P3 and dial-up) Don't know where we'll come in in this regard. Most database apps require some sort of runtime engine, and we'll be no different. - ease of deployment and maintenance (ie. how easy is it for an application to launch some updated that will fetch updates from the web) That seems to me more in the domain of apps created with Dabo, not Dabo itself. Python already has everything you need to do this, but you need to create the appropriate scripts for your server and your app. If Dabo can do all this, it could be a great solution to all those Of course, we're still pretty early in development; we have 0.3 scheduled to be released in the first week of January. But we do have our sights set pretty high. ___/ / __/ / / Ed Leafe http://leafe.com/ http://dabodev.com/ -- http://mail.python.org/mailman/listinfo/python-list
Re: More elegant way to cwd?
Kamilche wrote: For library modules there are already other and more elegant means. Well, I want to make a script execute without error regardless of where the current working directory is, and without having to make the user modify their PYTHONPATH variable or install something in site-packages. If you are talking about just a script, then this of course works out of the box without doing anything special. You just run the script and it works. If, on the other hand, the script requires access to certain shared *other* modules, then no, if you don't tell the script where to find those other modules, and they are not in the same folder as the script itself, then you can't do this. You do have to tell the Python where to find things... I'm unclear what your situation is, that you have shared modules that you want to use in various other scripts, and yet you have some strange restriction preventing you from telling Python where those are to be found except with custom code written in each script that will use the modules. Even if that really describes your (very bizarre, IMHO) situation, the least you could do is write the aforementioned code in a nice subroutine that you just cut and paste into each module, then call elegantly. It's code reuse, even if it's the most rudimentary sort of reuse. Is there a way to let the user just 'drag the folder' anywhere on their hard drive, and have it work, without having to modify any special system variables? Not sure exactly what you are looking for. I certain have folders of Python scripts that I can just drag here or there and have them work. When they need to use common library files, however, I take a moment to set that up ahead of time, using .pth files if I can't or won't install them in site-packages. -Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: pyUnitPerf
Grig [EMAIL PROTECTED] wrote: Problem with porting patterns/api's from java straight to python is that most of the outcome feels unpythonic. I'll not go about my own feelings python vs. java here now, but I just want to point out that there's already a rather large core of hard-python users who refuse to use pyUnit because of this, I'm curious what people find un-pythonic about PyUnit? I've used it, and while some parts of it seem a little over-complex to me, I don't see anything about it which is inherently un-pythonic. Is this just a case of Not Invented Here? -- http://mail.python.org/mailman/listinfo/python-list
Re: Other notes
[EMAIL PROTECTED] wrote: for i in 1..12: pass for c in a..z: pass @infix def interval(x, y): return range(x, y+1) # 2 parameters needed assert 5 interval 9 == interval(5,9) 10) There can be something in the middle between the def statement and the lambda. These will likely not appear in CPython standard, but Livelogix runs on top of the CPython VM and supports .. sequences and custom infix operators: http://logix.livelogix.com/tutorial/5-Standard-Logix.html 11) This is just a wild idea for an alternative syntax to specify a global variable inside a function. From: def foo(x): global y y = y + 2 (the last two lines are indented) To: def foo(x): global.y = global.y + 2 Beside the global.y, maybe it can exist a syntax like upper.y or caller.y that means the name y in the upper context. upper.upper.y etc. This will also likely never appear in Python. I like your idea though. I implemented the same exact thing a couple months ago. One difference though, you only need to type out the full global.y if you want to differentiate it from a local variable with the same name. 15) NetLogo is a kind of logo derived from StarLogo, implemented in Java. Show that this language is only partially a toy, and it can be useful to understand and learn nonlinear dynamics of many systems. If you want to do something like Netlogo but using Python instead of Logo, see: http://repast.sourceforge.net/ You can script repast in jython or you can script repast.net. Also, you might request the NetLogo and StarLogo developers to support Jython (in addition to Logo) scripting in their next version (which is already in development and supports 3D). -- http://mail.python.org/mailman/listinfo/python-list
Re: consequences of not calling object.__init__?
Peter Hansen, Quarta 29 Dezembro 2004 01:04, wrote: Maybe there's no such pronouncement, but unless there is a clear statement somewhere (and I believe I've missed it, if there is) that reads one should *always* call __init__ on the superclass even if one is just subclassing object and not dealing with multiple inheritance situations, then I would submit that the majority of Python code written using new-style classes would be broken should what you suggest above ever actually happen... starting with much of the code in the standard library (based on a quick glance at those modules whose contents match the re pattern class .*(object): . Things are kind weird at this point, since there are too many things to think about and to make a decision on what should be done and what is recommended to be done... Quoting from http://www.python.org/peps/pep-0008.html: (...) Designing for inheritance (...) Also decide whether your attributes should be private or not. The difference between private and non-public is that the former will never be useful for a derived class, while the latter might be. Yes, you should design your classes with inheritence in mind! (...) So, I don't really know which is correct: to always call the constructor of the parent class or just do that when it is needed by design... I think that based on the above quotation from PEP-0008 code in the standard library should be calling the parent class constructor. But then, I'm one of the people who never do that :-) -- Godoy. [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: pyUnitPerf
Roy Smith wrote: Grig [EMAIL PROTECTED] wrote: Problem with porting patterns/api's from java straight to python is that most of the outcome feels unpythonic. I'll not go about my own feelings python vs. java here now, but I just want to point out that there's already a rather large core of hard-python users who refuse to use pyUnit because of this, I'm curious what people find un-pythonic about PyUnit? I've used it, and while some parts of it seem a little over-complex to me, I don't see anything about it which is inherently un-pythonic. Is this just a case of Not Invented Here? I've seen 'py.test' proposed as as a more pythonic unit test framework. So its design may provide you with some clues. It can be found at: http://codespeak.net/py/current/doc/test.html#starting-point-py-test-command-line-tool As far as I can see, the defining feature of py.test is the simplicity of the API. Its impressively absent. -- Mike -- http://mail.python.org/mailman/listinfo/python-list
Re: getattr() woes
In article [EMAIL PROTECTED],
Thomas Rast [EMAIL PROTECTED] wrote:
I've found out about a fundamental problem of attribute lookup, the
hard way.
Maybe.
asyncore.py uses the following code:
class dispatcher:
# ...
def __getattr__(self, attr):
return getattr(self.socket, attr)
Now suppose that I'm asking for some attribute not provided by
dispatcher: The lookup mechanism will apparently try to find it
directly and fail, generating an AttributeError; next it will call
__getattr__ to find the attribute. So far, no problems.
But I used a property much like this:
import asyncore
class Peer(asyncore.dispatcher):
... def _get_foo(self):
... # caused by a bug, several stack levels deeper
... raise AttributeError('hidden!')
... foo = property(_get_foo)
...
You're not supposed to use properties with classic classes.
--
Aahz ([EMAIL PROTECTED]) * http://www.pythoncraft.com/
19. A language that doesn't affect the way you think about programming,
is not worth knowing. --Alan Perlis
--
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Re: Other notes
bearophileHUGS: [on Python's O(n) list insertion/deletion) at any place other than tail (My hypothesis: to keep list implementation a bit simpler, to avoid wasting memory for the head buffer, and to keep them a little faster, avoiding the use of the skip index S). Add its relative infrequent need. 2) I usually prefer explicit verbose syntax, instead of cryptic symbols (like decorator syntax), but I like the infix Pascal syntax .. to specify a closed interval (a tuple?) of integers or letters assert 1..9 == tuple(range(1,10)) for i in 1..12: pass for c in a..z: pass It's been proposed several times. I thought there was a PEP but I can't find it. One problem with it; what does for x in 1 .. a: do? (BTW, it needs to be 1 .. 12 not 1..12 because 1. will be interpreted as the floating point value 1.0.) What does a = MyClass() b = AnotherClass() for x in a .. b: print x do? That is, what's the generic protocol? In Pascal it works because you also specify the type and Pascal has an incr while Python doesn't. 3) I think it can be useful a way to define infix functions, like this imaginary decorator syntax: @infix def interval(x, y): return range(x, y+1) # 2 parameters needed This may allow: assert 5 interval 9 == interval(5,9) Maybe you could give an example of when you need this in real life? What does 1 + 2 * 3 interval 9 / 3 - 7 do? That is, what's the precedence? Does this only work for binary or is there a way to allow unary or other n-ary (including 0-ary?) functions? 4) The printf-style formatting is powerful, but I still think it's quite complex for usual purposes, and I usually have to look its syntax in the docs. I think the Pascal syntax is nice and simpler to remember (especially for someone with a little Pascal/Delphi experience ^_^), But to someone with C experience or any language which derives its formatting string from C, Python's is easier to understand than your Pascal one. A Python view is that there should be only one obvious way to do a task. Supporting both C and Pascal style format strings breaks that. Then again, having both the old % and the new PEP 292 string templates means there's already two different ways to do string formatting. For example this Delphi program: ... const a = -12345.67890; ... writeln(a:4:20); ... Gives: ... -12345.6789 Python says that's %.20f % -12345.67890 '-12345.678979453457' I don't think Pascal is IEEE enough. note also that the Pascal-style formatting strings are less capable than Python's, though few people use features like % 2.3f % -12.34 '-12.340' % 2.3f % 12.34 ' 12.340' 5) From the docs about round: ... But to avoid a bias toward rounding up there is another way do this: There are even more ways than that. See http://www.python.org/peps/pep-0327.html#rounding-algorithms The solution chosen was not to change 'round' but to provide a new data type -- Decimal. This is in Python 2.4. 6) map( function, list, ...) applies function to every item of list and return a list of the results. If list is a nested data structure, map applies function to just the upper level objects. In Mathematica there is another parameter to specify the level of the apply. .. I think this semantic can be extended: A real-life example would also be helpful here. What does map(len, Blah, level = 200) return? In general, most people prefer to not use map and instead use list comprehensions and (with 2.4) generator comprehensions. level=0 means that the map is performed up to the leaves (0 means infinitum, this isn't nice, but it can be useful because I think Python doesn't contain a built-in Infinite). You need to learn more about the Pythonic way of thinking of things. The usual solution for this is to have level = None. 7) Maybe it can be useful to extended the reload(module) semantic: reload(module [, recurse=False]) If recurse=True it reloads the module and recursively all the modules that it imports. It isn't that simple. Reloading modules isn't sufficient. Consider import spam a = spam.Eggs() reload(spam) print isinstance(a, spam.Eggs) This will print False because a contains a reference to the old Eggs which contains a reference to the old spam module. As I recall, Twisted has some super-reload code that may be what you want. See http://twistedmatrix.com/documents/current/api/twisted.python.rebuild.html 8) Why reload is a function and import is a statement? (So why isn't reload a statement too, or both functions?) import uses the underlying __import__ function. Consider using the __import__ function directly math = __import__(math) The double use of the name math is annoying and error prone. It's more complicated with module hierarchies. xml = __import__(xml.sax.handler) xml.sax.handler module 'xml.sax.handler' from '/sw/lib/python2.3/xml/sax/handler.pyc' xml.sax.saxutils Traceback (most recent call last): File
Re: Other notes
Andrew Dalke [EMAIL PROTECTED] writes: What does a = MyClass() b = AnotherClass() for x in a .. b: print x do? That is, what's the generic protocol? .. just becomes an operator like + or whatever, which you can define in your class definition: class MyClass: def __dotdot__(self, other): return xrange(self.whatsit(), other.whatsit()) The .. operation is required to return an iterator. -- http://mail.python.org/mailman/listinfo/python-list
Re: Other notes
[EMAIL PROTECTED] wrote:
4) The printf-style formatting is powerful, but I still think it's
quite complex for usual purposes, and I usually have to look its syntax
in the docs. I think the Pascal syntax is nice and simpler to remember
(especially for someone with a little Pascal/Delphi experience ^_^), it
uses two : to format the floating point numbers (the second :number
is optional). For example this Delphi program:
{$APPTYPE CONSOLE}
const a = -12345.67890;
begin
writeln(a);
writeln(a:2:0);
writeln(a:4:2);
writeln(a:4:20);
writeln(a:12:2);
end.
Gives:
-1.2345678900E+0004
-12346
-12345.68
-12345.6789
-12345.68
(The last line starts with 3 spaces)
Even after looking at your example, I have no idea what the two numbers
on each side of the :'s do. The last number appears to be the number of
decimal places to round to, but I don't know what the first number does.
Since I can't figure it out intuitively (even with examples), I don't
think this syntax is any less inscrutable than '%width.decimalsf'.
My suspicion is that you're just biased by your previous use of Pascal.
(Note that I never used Pascal or enough C to use string formatting
before I used Python, so I'm less biased than others may be in this
situation.)
6) map( function, list, ...) applies function to every item of list and
return a list of the results. If list is a nested data structure, map
applies function to just the upper level objects.
In Mathematica there is another parameter to specify the level of the
apply.
So:
map(str, [[1,[2]], 3])
==
['[1, [2]]', '3']
With a hypothetical level (default level = 1, it gives the normal
Python map):
map(str, [[1,[2]], 3], level=1)
==
['[1, [2]]', '3']
map(str, [[1,[2]], 3], level=2)
==
['1', '[2]', '3']
I think this semantic can be extended:
level=0 means that the map is performed up to the leaves (0 means
infinitum, this isn't nice, but it can be useful because I think Python
doesn't contain a built-in Infinite).
level=-1 means that the map is performed to the level just before the
leaves.
Level=-n means that the map is performed n levels before the leaves.
This packs two things into map -- the true mapping behavior (applying a
function to a list) and the flattening of a list. Why don't you lobby
for a builtin flatten instead? (Also, Google for flatten in the
python-list -- you should find a recent thread about it.)
10) There can be something in the middle between the def statement and
the lambda. For example it can be called fun (or it can be called
def still). With it maybe both def and lambdas aren't necessary
anymore. Examples:
cube = fun x:
return x**3
(the last line is indented)
sorted(data, fun x,y: return x-y)
(Probably now it's almost impossible to modify this in the language.)
Google the python-list for 'anonymous function' or 'anyonymous def' and
you'll find a ton of discussion about this kind of thing. I'll note
only that your first example gains nothing over
def cube(x):
return x**3
and that your second example gains nothing over
sorted(data, lambda x, y: return x-y)
or
sorted(data, operator.sub)
11) This is just a wild idea for an alternative syntax to specify a
global variable inside a function. From:
def foo(x):
global y
y = y + 2
(the last two lines are indented)
To:
def foo(x): global.y = global.y + 2
Well, you can do:
def foo(x):
globals()['y'] = globals()['y'] + 2
Not exactly the same syntax, but pretty close.
13) In Mathematica language the = has the same meaning of Python, but
:= is different:
lhs := rhs assigns rhs to be the delayed value of lhs. rhs is
maintained in an unevaluated form. When lhs appears, it is replaced by
rhs, evaluated afresh each time.
I don't know if this can be useful...
You can almost get this behavior with lambdas, e.g.:
x = lambda: delayed_expression()
then you can get a new instance of the expression by simply doing:
new_instance = x()
I know this isn't exactly what you're asking for, but this is one
current possibility that does something similar. You might also look at:
http://www.python.org/peps/pep-0312.html
which suggests a simpler syntax for this kind of usage.
Steve
--
http://mail.python.org/mailman/listinfo/python-list
Using python to deploy software
Has anyone used python to deploy (non-python) software on a Windows network? -- http://mail.python.org/mailman/listinfo/python-list
Re: Other notes
Andrew Dalke wrote: I must say it's getting pretty annoying to say things like when would this be useful? and have you read the documentation? for your statements. I'll second that. Please, Bearophile, do us the courtesy of checking (1) Google groups archive of the mailing list: http://groups-beta.google.com/group/comp.lang.python and (2) The Python Enhancement Proposals: http://www.python.org/peps/ before posting another such set of questions. While most of the people on this list are nice enough to answer your questions anyway, the answers are already out there for at least half of your questions, if you would do us the courtesy of checking first. Thanks! Steve -- http://mail.python.org/mailman/listinfo/python-list
Re: getattr() woes
[EMAIL PROTECTED] (Aahz) writes:
In article [EMAIL PROTECTED],
Thomas Rast [EMAIL PROTECTED] wrote:
class dispatcher:
# ...
def __getattr__(self, attr):
return getattr(self.socket, attr)
import asyncore
class Peer(asyncore.dispatcher):
... def _get_foo(self):
... # caused by a bug, several stack levels deeper
... raise AttributeError('hidden!')
... foo = property(_get_foo)
...
You're not supposed to use properties with classic classes.
Even if dispatcher was a new-style class, you still get the same
behaviour (or misbehaviour) -- Peer().foo still raises AttributeError
with the wrong message.
A simple workaround is to put a try ... except AttributeError block in
his _get_foo(), which would re-raise with a different error that
wouldn't be caught by getattr. You could even write a property
replacement for that:
class HiddenAttributeError(Exception):
... pass
def robustprop(fget):
... def wrapped_fget(self):
... try:
... return fget(self)
... except AttributeError, e:
... raise HiddenAttributeError(*e.args)
... return property(fget=wrapped_fget)
Ideally, I think the better way is if getattr, when raising
AttributeError, somehow reused the old traceback (which would point
out the original problem). I don't know how to do that, though.
--
||\/|
/--\
|David M. Cooke
|cookedm(at)physics(dot)mcmaster(dot)ca
--
http://mail.python.org/mailman/listinfo/python-list
Why tuples use parentheses ()'s instead of something else like 's?
Tuples are defined with regards to parentheses ()'s as everyone knows.
This causes confusion for 1 item tuples since (5) can be interpreted
as a tuple OR as the number 5 in a mathematical expression
such as x = (5) * (4+6).
Wouldn't it have been better to define tuples with 's or {}'s or
something else to avoid this confusion??
Perhaps ()'s are a good idea for some other reason I don't know?
Please enlighten me as I really want to know.
Chris
P.S. I love Python!
--
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Re: Using python to deploy software
I haven't but one of my friends have used Pyro (Python Remote Objects) to do so. You basically need to write a custom Pyro server and run it on a central machine. Your pyro clients can be installed on the machines where the software need to be installed. For more details and similar ideas refer the project page of pyro at http://pyro.sourceforge.net/projects.html . -Anand -- http://mail.python.org/mailman/listinfo/python-list
Re: Why tuples use parentheses ()'s instead of something else like 's?
[EMAIL PROTECTED] wrote:
Tuples are defined with regards to parentheses ()'s as everyone knows.
This causes confusion for 1 item tuples since (5) can be interpreted
as a tuple OR as the number 5 in a mathematical expression
such as x = (5) * (4+6).
No, (5) is always the number 5. To make a one-element tuple, use (5,).
Wouldn't it have been better to define tuples with 's or {}'s or
something else to avoid this confusion??
Perhaps ()'s are a good idea for some other reason I don't know?
Actually, for non-empty tuples, the parentheses aren't really necessary,
unless code is ambiguous.
x = 1, 2, 3
x
(1, 2, 3)
y = 5,
y
(5,)
but:
print 8, 9 # not a tuple
8 9
print (8, 9)
(8, 9)
HTH,
--
Hans Nowak
http://zephyrfalcon.org/
--
http://mail.python.org/mailman/listinfo/python-list
Re: Why tuples use parentheses ()'s instead of something else like 's?
[EMAIL PROTECTED] wrote:
Wouldn't it have been better to define tuples with 's or {}'s or
something else to avoid this confusion??
The way I see it, tuples are just a way of having a function return
multiple values at once. When you think of them that way, you don't even
need parenthesis:
def foo():
if we_found_stuff:
return 200, 'long and boring result'
else:
return 404, 'nothing found'
status_code, body = foo()
If foo() only needed to return one value, it would do so in the normal
way, and you wouldn't need to worry about 1-tuples.
--
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Re: Why tuples use parentheses ()'s instead of something else like 's?
* [EMAIL PROTECTED] Perhaps ()'s are a good idea for some other reason I don't know? One-element tuples are written as (4,). -- Marius Bernklev URL: http://www.ping.uio.no/~mariube/ -- http://mail.python.org/mailman/listinfo/python-list
Re: Python on Linux
Austin [EMAIL PROTECTED] wrote: On Red Hat 9, Python is installed by default and it's version is 2.2.2 If I want to upgrade Python to 2.3.4(newer version), how could I do? If I compile source code of Python, how do I uninstall the old version? You don't want to uninstall the old version. Red Hat installs packages that are needed for its configuration scripts. -- - Tim Roberts, [EMAIL PROTECTED] Providenza Boekelheide, Inc. -- http://mail.python.org/mailman/listinfo/python-list
Re: Other notes
Paul Rubin wrote: .. just becomes an operator like + or whatever, which you can define in your class definition: class MyClass: def __dotdot__(self, other): return xrange(self.whatsit(), other.whatsit()) The .. operation is required to return an iterator. Ahh, I see. This should be put into a PEP. Some obvious questions: - .. or ... ? The latter is already available for use in slices - If ... should the name be __ellipsis__? If .. should the name be __range___? - Should range(x, y) first attempt x.__range__(y)? - Can it be used outside of a for statement? Ie, does x = a ... b return a generic iterator? Almost certainly as that fits in nicely with the existing 'for' syntax. - What's the precedence? Given x = a .. b .. c x = 1 + 2 .. 5 * 3 x = 1 ** 5 .. 4 ** 2 etc., what is meant? Most likely .. should have the lowest precedence, evaluated left to right. - is there an __rdotdot__? - any way to specify use the normal beginning? Like for x in .. 5: # same as 0 .. 5 -or (the oft rejected)- for x in 5: - any way to specify ad infinitum? Like for x in 0 .. Infinity: -or- for x in 0 ... : - does for x in 10 .. 0 the same as xrange(10,0) (what you propose) or xrange(10, 0, -1)? - do strings work for len(s) 1? Eg, A000 .. A999? - What do you think of (assuming the use of ...) for x in 0.100:? - What's the advantage of .. over, say a function or method? That is, why does the new binary operator prove so useful? In one of my gedanken experiments I considered getting the 10th through 20th prime for x in primes(10) .. primes(20): but that seems clumsier than for x in primes_between(10, 20): in part because it requires primes(10) to have some meaning. I suppose for x in primes(10) .. 20: could also work though that should in my mind generate primes up to the number 20 and not the 20th prime. Note that primes(10) cannot return the 10th prime as the value 29. Andrew [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
