Fredericksburg, VA ZPUG July 12: Jim Fulton's buildout package, Python + Fortran, roundtable
(Apologies for the especially late notice; for some reason these announcements did not go out when I sent them Monday to python- announce-list and zope-announce) Please join us Wed., July 12, 7:30-9:00 PM, for another meeting of the Fredericksburg, VA Zope and Python User Group (ZPUG). We will have a presentation, a lightning talk, a roundtable, and some good snacks. - Jim Fulton will present the talk he gave last week at EuroPython on zc.buildout. The zc.buildout project provides support for creating applications, especially Python applications. It provides tools for assembling applications from multiple parts, Python or otherwise. See http://svn.zope.org/zc.buildout/trunk/. - John Kimball will present a lightning talk of Fortran in Python. - We will have a roundtable discussion of Python and Zope topics. Gary General ZPUG information When: second Wednesday of every month, 7:30-9:00. Where: Zope Corporation offices. 513 Prince Edward Street; Fredericksburg, VA 22408 (tinyurl for map is http://tinyurl.com/duoab). Parking: Zope Corporation parking lot; entrance on Prince Edward Street. Topics: As desired (and offered) by participants, within the constraints of having to do with Python or Zope. Mailing list: [EMAIL PROTECTED] Contact: Gary Poster ([EMAIL PROTECTED]) -- http://mail.python.org/mailman/listinfo/python-announce-list Support the Python Software Foundation: http://www.python.org/psf/donations.html
Dr. Dobb's Python-URL! - weekly Python news and links (Jul 12)
QOTW: Write code, not usenet posts. - Fredrik Lundh If an embedded return isn't clear, the method probably needs to be refactored with 'extract method' a few times until it is clear. - John Roth The comp.lang.python collective has become quite expert at answering Which book should I read? questions. Note particularly the precision of gene tani, John Salerno, and Vittorio: http://groups.google.com/group/comp.lang.python/browse_thread/thread/4a9e9a76c623e451/ Programmers who prefer Ruby over Python explain why: http://groups.google.ca/group/comp.lang.ruby/browse_frm/thread/d7469d9317913151/18fcafa96ecdeef5?tvc=1#18fcafa96ecdeef5 If you don't believe all the other evidence that 'twould be no blessing for one thread to be its brother's keeper, perhaps the testimony of Javans will sway you: http://groups.google.com/group/comp.lang.python/msg/232ab0131bb3685c Keep in mind, anyway, that threading is overrated (overused, over...): http://groups.google.com/group/comp.lang.python/browse_thread/thread/b6d4e2be18c2267a/ PataPata is a wild experiment that touches on GUI building, educational constructivism, and simulations. Paul D. Fernhout comments extensively: http://mail.python.org/pipermail/tkinter-discuss/2006-July/000825.html Everything Python-related you want is probably one or two clicks away in these pages: Python.org's Python Language Website is the traditional center of Pythonia http://www.python.org Notice especially the master FAQ http://www.python.org/doc/FAQ.html PythonWare complements the digest you're reading with the marvelous daily python url http://www.pythonware.com/daily Mygale is a news-gathering webcrawler that specializes in (new) World-Wide Web articles related to Python. http://www.awaretek.com/nowak/mygale.html While cosmetically similar, Mygale and the Daily Python-URL are utterly different in their technologies and generally in their results. For far, FAR more Python reading than any one mind should absorb, much of it quite interesting, several pages index much of the universe of Pybloggers. http://lowlife.jp/cgi-bin/moin.cgi/PythonProgrammersWeblog http://www.planetpython.org/ http://mechanicalcat.net/pyblagg.html comp.lang.python.announce announces new Python software. Be sure to scan this newsgroup weekly. http://groups.google.com/groups?oi=djqas_ugroup=comp.lang.python.announce Python411 indexes podcasts ... to help people learn Python ... Updates appear more-than-weekly: http://www.awaretek.com/python/index.html Steve Bethard, Tim Lesher, and Tony Meyer continue the marvelous tradition early borne by Andrew Kuchling, Michael Hudson and Brett Cannon of intelligently summarizing action on the python-dev mailing list once every other week. http://www.python.org/dev/summary/ The Python Package Index catalogues packages. http://www.python.org/pypi/ The somewhat older Vaults of Parnassus ambitiously collects references to all sorts of Python resources. http://www.vex.net/~x/parnassus/ Much of Python's real work takes place on Special-Interest Group mailing lists http://www.python.org/sigs/ Python Success Stories--from air-traffic control to on-line match-making--can inspire you or decision-makers to whom you're subject with a vision of what the language makes practical. http://www.pythonology.com/success The Python Software Foundation (PSF) has replaced the Python Consortium as an independent nexus of activity. It has official responsibility for Python's development and maintenance. http://www.python.org/psf/ Among the ways you can support PSF is with a donation. http://www.python.org/psf/donate.html Kurt B. Kaiser publishes a weekly report on faults and patches. http://www.google.com/groups?as_usubject=weekly%20python%20patch Although unmaintained since 2002, the Cetus collection of Python hyperlinks retains a few gems. http://www.cetus-links.org/oo_python.html Python FAQTS http://python.faqts.com/ The Cookbook is a collaborative effort to capture useful and interesting recipes. http://aspn.activestate.com/ASPN/Cookbook/Python Among several Python-oriented RSS/RDF feeds available are http://www.python.org/channews.rdf http://bootleg-rss.g-blog.net/pythonware_com_daily.pcgi http://python.de/backend.php For more, see http://www.syndic8.com/feedlist.php?ShowMatch=pythonShowStatus=all The old Python To-Do List now lives principally in a SourceForge reincarnation. http://sourceforge.net/tracker/?atid=355470group_id=5470func=browse
Chicago Python User Group: Thurs. July 13, 2006 7pm.
This will be our best meeting yet. When Thurs. July 13, 2006. 7pm. Location Performics, downtown Chicago 180 N LaSalle St, Suite 1100, Please RSVP http://www.chipy.org/RSVP ** There will probably be a pre-meeting at a nearby cafe for early arrivals. Check the mailing list for more. Topics -- * CrunchyFrog and SpinyNorman (DocTests in educational Python) * shlex * Perl 6 compared to Python About ChiPy --- ChiPy is a group of Chicago Python Programmers, l33t, and n00bs. Meetings are held monthly at various locations around Chicago. Also, ChiPy is a proud sponsor of many Open Source and Educational efforts in Chicago. Stay tuned to the mailing list for more info. ChiPy website: http://chipy.org ChiPy Mailing List: http://mail.python.org/mailman/listinfo/chicago Python website: http://python.org Forward this on. -- http://mail.python.org/mailman/listinfo/python-announce-list Support the Python Software Foundation: http://www.python.org/psf/donations.html
Re: Restricted Access
Do you have an IBM s/370 running VM/CMS? VM was sort of an OS for running multiple OSs, so it would be the restricted environment G I'm having currently working on OS/2 and Linux platform, I've designed a web based ide for python and i wish to restrict some commands and user can only access i.e rwx in his folder. Best! -- http://mail.python.org/mailman/listinfo/python-list
Re: uTidylib question..
In [EMAIL PROTECTED], bruce wrote: import tidy s = tidy.parseString(foo) which runs the information in foo through tidy, for cleaning. this results in s being a document object print s will display the contents of the object. If this means it prints out what you want as a string… my question, can the document object be turned/translated into a string var? …then yes: ``str(s)`` Ciao, Marc 'BlackJack' Rintsch -- http://mail.python.org/mailman/listinfo/python-list
Re: Python-2.5beta1 crash
Robin Becker wrote:
First off there may be a bunch of other C extensions involved including
PIL, but I built them all against this beta. What should I do to refine
the error? Do I start with trying to establish which of the tests is
guilty or build from source in debug mode and attempt to find the
problem from below.
I would personally run Python in debug mode. Set a break point on
Py_FatalError, and then walk the C stack to see where it comes from.
Of course, the specific error comes from
static void
intern_strings(PyObject *tuple)
{
Py_ssize_t i;
for (i = PyTuple_GET_SIZE(tuple); --i = 0; ) {
PyObject *v = PyTuple_GET_ITEM(tuple, i);
if (v == NULL || !PyString_CheckExact(v)) {
Py_FatalError(non-string found in code slot);
}
PyString_InternInPlace(PyTuple_GET_ITEM(tuple, i));
}
}
which in turn is called from PyCode_New, in these calls:
intern_strings(names);
intern_strings(varnames);
intern_strings(freevars);
intern_strings(cellvars);
So it appears you are trying to create a code object, where
a name, varname, freevar name, or cellvar name is not a string.
This is indeed fatal: names in Python are always strings.
Regards,
Martin
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Re: Restricted Access
Le mercredi 12 juillet 2006 08:17, iapain a écrit : I'm having currently working on OS/2 and Linux platform, I've designed a web based ide for python and i wish to restrict some commands There is a restricted environment in Zope for TTW python scripts and ZPT/DTML . These scripts are run in the Zope process in a very restricted environment which forbid the use of most builtins and allow the import of a limited list of modules. Why don't use the RestrictedPython module from Zope (2.8 and up) and adapt it a bit. It seems loose coupled to the Zope internals (except for the multimapping class which is an extension class, but I doubt it's really a problem). It shouldn't be a too hard. You'll need to make your own AccessControl/ZopeGuards.py-like module, and probably subclass the RestrictionMutator to enable/disable certain functionnality (interdiction of names beginning by '_' for example is hard coded). At last, you will get a simple example of the usage of the whole beast from your own interpreter in Products/PythonScripts. and user can only access i.e rwx in his folder. This should be possible by providing a wrapper function for file and open (see the Guards.py module). IMO, it worth to be tried, and I don't see any other short-term, less hacky, solution. regards, -- _ Maric Michaud _ Aristote - www.aristote.info 3 place des tapis 69004 Lyon Tel: +33 426 880 097 -- http://mail.python.org/mailman/listinfo/python-list
Re: hash() yields different results for different platforms
Grant Edwards wrote:
On 2006-07-11, Qiangning Hong [EMAIL PROTECTED] wrote:
However, when I come to Python's builtin hash() function, I
found it produces different values in my two computers! In a
pentium4, hash('a') - -468864544; in a amd64, hash('a') -
12416037344. Does hash function depend on machine's word
length?
Apparently. :)
The low 32 bits match, so perhaps you should just use that
portion of the returned hash?
hex(12416037344)
'0x2E40DB1E0L'
hex(-468864544 0x)
'0xE40DB1E0L'
hex(12416037344 0x)
'0xE40DB1E0L'
hex(-468864544 0x)
'0xE40DB1E0L'
Is this relationship (same low 32 bits) guaranteed? Will it change in
the future version?
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Re: hash() yields different results for different platforms
[Grant Edwards] ... The low 32 bits match, so perhaps you should just use that portion of the returned hash? hex(12416037344) '0x2E40DB1E0L' hex(-468864544 0x) '0xE40DB1E0L' hex(12416037344 0x) '0xE40DB1E0L' hex(-468864544 0x) '0xE40DB1E0L' [Qiangning Hong] Is this relationship (same low 32 bits) guaranteed? No. Nothing about hashes is guaranteed, except that when x and y are of a hashable type, and x == y, then hash(x) == hash(y) too. Will it change in the future version? That's possible, but not planned. Note that the guts of string hashing in CPython today is implemented via while (--len = 0) x = (103*x) ^ *p++; where x is C type long, and the C language doesn't even define what that does (behavior when signed multiplication overflows isn't defined in C). -- http://mail.python.org/mailman/listinfo/python-list
Re: Is there a limit to os.popen()?
In article [EMAIL PROTECTED], Carl J. Van Arsdall [EMAIL PROTECTED] wrote: Lawrence D'Oliveiro wrote: In article [EMAIL PROTECTED], Carl J. Van Arsdall [EMAIL PROTECTED] wrote: Well, running the make on the command line seems to work just fine, no errors at all. What about running it as make kernelrelease | cat This way the output goes to a pipe, which is what happens when it's called from your script. Do you see those broken pipe messages after a few minutes in this case? Alright, so I tried that line in the interpreter and got the same problem. No, I wanted you to try it from a bash command prompt, to try to simulate the environment when the make command on its own is invoked via popen. -- http://mail.python.org/mailman/listinfo/python-list
Re: file.readlines() and IOError exceptions
Astan Chee wrote: now the file Im trying to read has recently had alot of read/writes from other users/threads/etc, so every now and again I get a IOError: [Errno 9] Bad file descriptor I know this has something to do with not being able to read while some filehandles are open (or is it?).. EBADF usually means that you're trying to read from a file that's no longer open. other users shouldn't be able to cause that error; I'd suspect sloppy thread programming... /F -- http://mail.python.org/mailman/listinfo/python-list
Re: Restricted Access
You'll need to make your own AccessControl/ZopeGuards.py-like module, and probably subclass the RestrictionMutator to enable/disable certain functionnality (interdiction of names beginning by '_' for example is hard coded). Your reply is pretty hopeful, I saw that one, its the only fractional part. I'm agree with others that I need to setup a safe runtime enviornment rather than detecting harmful code. This should be possible by providing a wrapper function for file and open (see the Guards.py module). Thats a nice idea, I guess it should work. I should try it really quick! Thanks! Best! iapain -- http://mail.python.org/mailman/listinfo/python-list
Re: Sets and Membership Tests
JK, You are correct to implement __hash__ and __eq__. The problem is how you implemented them. Usually your __eq__ method should compare the necessary attributes of the objects for equality. The __hash__ should return a 32-bit integer. Your best bet is probably to return a hash of hashes of your attributes that are used in equality comparison. What this means is that your attributes used to produce the __hash__ should also be hashable. This is important yet not immediatly obvious. So you could for example return hash( (attribute1, attribute2, attribute3) ), where attribute1, attribute2, attribute3 are all hashable. Of course, you provided no code and no error messages (the 'SoFarNoLuck' exception is not descriptive enough ; ) Hope this helps JKPeck wrote: I would like to be able use sets where the set members are objects of a class I wrote. I want the members to be distinguished by some of the object content, but I have not figured out how a set determines whether two (potential) elements are identical. I tried implementing __eq__ and __ne__ and __hash__ to make objects with identical content behave as identical for set membership, but so far no luck. I could subclass set if necessary, but I still don't know what I would need to override. TIA for any advice you can offer. -- http://mail.python.org/mailman/listinfo/python-list
Re: Is there a limit to os.popen()?
Carl J. Van Arsdall wrote:
I'm not sure the proper way to phrase the question, but let me try.
Basically, I'm working with a script where someone wrote:
kr = string.strip(os.popen('make kernelrelease').read())
And then searches kr to match a regular expression.
This seems to have been working, however lately when this line executes
I get a number of messages to stderr after several minutes of execution:
cat: write error: Broken pipe
cat: write error: Broken pipe
cat: write error: Broken pipe
I know the output from this make has been growing (make applies some
patches and the patch list is growing). Does os.popen() have some kind
of read buffer limit that i'm hitting which is causing things to break?
While I can't tell you where the error is, I *can* tell you that the
message is caused when some proces that's writing to a pipe sees the
pipeline's reader close the pipe while the writer is still sending data.
If you are seeing alot of error messages you shoudl really redirect the
standard error to a file to avoid them cluttering up your console.
regards
Steve
--
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Holden Web LLC/Ltd http://www.holdenweb.com
Skype: holdenweb http://holdenweb.blogspot.com
Recent Ramblings http://del.icio.us/steve.holden
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Re: Object Persistence Using a File System
Chris Spencer wrote:
Before I get too carried away with something that's probably
unnecessary, please allow me to throw around some ideas. I've been
looking for a method of transparent, scalable, and human-readable object
persistence, and I've tried the standard lib's Shelve, Zope's ZODB,
Divmod's Axiom, and others. However, while they're all useful, none
satisfies all my criteria. So I started writing some toy code of my own:
http://paste.plone.org/5227
All my code currently does is transparently keep track of object changes
without requiring any special coding on part of the user, and a function
to convert an object to a file system hierarchy of folders and files.
Please, let me know what you think.
As you say, using filesystem for fine-grained persistance may not be the
most efficient solution. I also wonder how (if...) you intend to address
concurrent R/W access and transactions...
A few observations and questions :
- you should avoid tests on concrete types as much as possible - at
least use isinstance
- tuples are immutable containers. What about them ?
- what about multiple references to a same object ?
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
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Re: hash() yields different results for different platforms
Qiangning Hong wrote: /.../ add a hash column in the table, make it a unique key at this point, you should have slapped yourself on the forehead, and gone back to the drawing board. /F -- http://mail.python.org/mailman/listinfo/python-list
Re: import and global namespace
Dennis Lee Bieber wrote:
On Wed, 12 Jul 2006 02:48:44 +0200, Bruno Desthuilliers
[EMAIL PROTECTED] declaimed the following in
comp.lang.python:
nate a écrit :
I'd like a module than I'm importing to be able to use objects in the
global namespace into which it's been imported. is there a way to do
that?
snip
NB : FWIW, the clean solution probably involve a class...
Or a common module that both (all) import...
I'm afraid this would be as messy. Having one module depending on
implicits external names is a good way to spaghetti code.
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
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Re: Relying on the behaviour of empty container in conditional statements
Steven D'Aprano schreef: If seq can be None as well as a sequence, doing a test if len(seq) 0 won't save you because len(None) will fail. You need an explicit test for seq being None: if seq is not None and len(seq) 0 Or even better: if seq which Just Works regardless of the type of seq. Yes, true. I agree that testing in a Boolean context works best in those cases. After a good night's sleep I remember why I felt uneasy doing it like that: I feel that 'if seq' should be synonym with 'if seq is not None', but I can't explain why. No rational reasons I think; it's probably just from being used to C and C++ where 'if (p)' in pointer contexts is used as synonym for 'if (p != NULL)'. In general I don't have too many problems using Python idioms instead of C or C++ idioms, but apparently sometimes my years of experience in these languages sometimes show trough in Python. Luckily my BASIC habits have died out long ago. -- If I have been able to see further, it was only because I stood on the shoulders of giants. -- Isaac Newton Roel Schroeven -- http://mail.python.org/mailman/listinfo/python-list
Re: How to use images at the bachground?
pipehappy wrote: hi all, how to get out of the python shell which is executing a command? how to use images in the background of a page in Tkinter? on Unix, ctrl-c or ctrl-d may do the job. on Windows, ctrl-z will do Hi I presume you meant putting a image as a background for a Tkinter app. If so , try Tkinter.Canvas. Best of luck sree -- http://mail.python.org/mailman/listinfo/python-list
Re: help a newbie with a IDE/book combination
On 9 Jul 2006 16:42:27 -0700 [EMAIL PROTECTED] wrote: Hi, I already have a couple of newbie books on Python itself, but would rather get started with a nice to use IDE and I am therefore looking for a good IDE to learn Python. Is there a good IDE which would be well documented out there? Python comes with IDLE. It should be in /usr/local/bin If not try: python2.4 /usr/local/lib/python2.4/idlelib/idle.py I like idle as a beginner because it's easy for me to test out my simple little learning scripts while in it. (though I figure there's probably a way to do that from within vim or emacs) As some suggested, as a beginner you don't need much of a super powered IDE. If I wasn't using IDLE, I'd be using vim or gvim. CronoCloud (Ron Rogers Jr.) -- http://mail.python.org/mailman/listinfo/python-list
Re: first book about python
On Sun, 09 Jul 2006 03:41:52 +0300 IOANNIS MANOLOUDIS [EMAIL PROTECTED] wrote: I want to learn python. I am looking for a book which will help me get started and should contain the foundations. I am not looking for the Python bible. Any recommendations? Ioannis Hmm, no one has mentioned Python Programming for the Absolute Beginner (second edition) by Michael Dawson. http://www.amazon.com/gp/product/1598631128/102-5443736-1342538?v=glancen=283155 Yes, it's very game oriented, but it's also very newbie oriented. I've slso downloaded some Python tutorials: I've got the Python version of How to Think Like a Computer Scientist: http://www.ibiblio.org/obp/thinkCSpy/ And Dive into Python (available online as well as paper): http://diveintopython.org/ Hope this helps. CronoCloud (Ron Rogers Jr.) -- http://mail.python.org/mailman/listinfo/python-list
Re: Augument assignment versus regular assignment
On 2006-07-11, Piet van Oostrum [EMAIL PROTECTED] wrote: Antoon Pardon [EMAIL PROTECTED] (AP) wrote: AP As I read the language reference the x stands for a target expression. AP Now what does it mean to evaluate a target expression like col[key]. AP IMO it means finding the location of the item in the collection: the AP bucket in the directory, the node in the tree ... grosso mode it AP boils down to the call to __setitem__ or __getitem__ depending AP on where the col[key] was located in the line (or if you prefer AP the view from the interpreter it boils down to the BINARY_SUBSCR AP and STORE_SUBSCR opcodes). AP So if the language reference seems to implies that col[key] will AP only be evaluated once in a line like: col[key] += 1 I expect AP only one call from __setitem__ or __getitem__ (or only one AP from BINARY_SUBSCR or STORE_SUBSCR) You need both the __setitem__ and the __getitem__ otherwise it won't work. I think the evaluated once clause is for cases like: f(a)[g(b)] += 1 where f and/or g have side effects. These side effects should then take place only once. Side effects in __setitem__ and __getitem__ is not what it is talking about. Well I'll start on an possitive note and accept this. Now I'd like you to answer some questions. 1) Do you think the langauge reference makes it clear that this is how the reader has to understand things. 2a) In case you answer yes to question (1). Can you explain me how I have to read the language reference in order to deduce this is indeed the way things should be understood. 2b) In case you anser no to question (1). Do you find it unreasonable that I ask that the language reference would be rewritten here so that your explanation can be (more easily) deduced from it. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: Object Persistence Using a File System
Chris, Interesting concept. But why is there a need for a human readable object persistence that is x10 slower than pickle? In other words present a good use case with a rationale (i.e. your criteria that you mentioned). The only one I can think of so far is debugging. Also some objects are inherently not human readable (they are large, or just binary/array data for example), or you could simply end up having so many of them (10GB worth of disk space) that just due to the volume they will become not very readable and you would need some kind of a custom query mechanism (or find+grep) to search through your objects if you wanted to read/edit values in them. In your code comments I saw that another reason is resistance to corruption. I think that a database that is backed up regularly is probably a better solution. Besides, sometimes you want your failure to be dramatic (go down with a bang!) so it gets your attention and you can restore everything with a backup. Otherwise, with a tens of thousands of files, some of them might end up being corrupted before your next filesystem check gets to them, by then, the corruption could spread (your program would load it, perform computations, persist the wrong results and so on), and you wouldn't even notice it. Hope these comments help, Nick V. Chris Spencer wrote: Before I get too carried away with something that's probably unnecessary, please allow me to throw around some ideas. I've been looking for a method of transparent, scalable, and human-readable object persistence, and I've tried the standard lib's Shelve, Zope's ZODB, Divmod's Axiom, and others. However, while they're all useful, none satisfies all my criteria. So I started writing some toy code of my own: http://paste.plone.org/5227 All my code currently does is transparently keep track of object changes without requiring any special coding on part of the user, and a function to convert an object to a file system hierarchy of folders and files. Please, let me know what you think. Thanks, Chris -- http://mail.python.org/mailman/listinfo/python-list
Re: Accessors in Python (getters and setters)
Lousy Attribute Name:
self.tmp
Accessors:
set_temporary_buffer
get_temporary_buffer
The attribute name I chose, tmp sucks. I have used that name in
dozens of places spanning over 27000 LOC. There's a chance that other
develops might misinterpret exactly what tmp does. Plus I don't want
emails from other developers querying me about what tmp is/does.
tmp is obvious to me, but not necessarily to others. Now compare that
to the accessors. Not only do they improve readability at the expense
of more code, they actually allow me to change the lousily named
attribute tmp to temporary_buffer without grepping, seding,
searching, replacing and praying. Sure, if you are dealing with less
than a 1000LOC you can get away with using tmp or renaming it easily.
But if you are dealing with a much larger code base and more
developers, issues like this rapidly become a nuisance.
Yes, it is possible to name crappy accessors too (e.g set_tmp/get_tmp).
But developers tend to pay more attention to given methods/functions
less crappy names, at least when compared to data attributes. This
stems from the fact that in many languages data attributes aren't
usually part of the API, as well as the whole OO(Encapsulation) blah
blah. I know I would not name the accessors set_tmp/get_tmp, because my
philosophy is that methods/functions need to have meaningful names and
state their intended purpose. I don't hold data attributes to such
standards and I imagine many developers don't either and least based on
other people's code I've read. Plus there are many occassions when
attributes are not intended to be APIs, but eventually become one.
After all most data attributes are created with the purpose of serving
methods.
Bruno Desthuilliers wrote:
mystilleef wrote:
Hello,
Thanks for the responses. The reason I want to change the name of the
attribute is because it doesn't reflect the purpose of the attribute,
anymore. The attribute was originally a string object, but not anymore.
It is primarily a readability issue. There are also a few key
attributes I don't want developers, including myself, fiddling with.
Properties /accessors are good because they allow you to encapsulate
attributes so you can change implementations at will. Some of you have
argued I would have needed to change accessor names too if I had
misnamed them earlier. It's hard to say. I find myself changing the
names of attributes a lot more frequently than I do functions or
methods. Choosing a crappy attribute name is effortless for me,
especially during intense coding sessions. I usually realize I've
choosing a crappy attribute name the next day, sometimes even later.
However, I put a lot more effort into choosing method and function
names, especially when I know it may likely be a public API.
What you need to understand here is that in Python,
1/ methods *are* attributes
2/ every attribute whose name is not prefixed by a leading underscore is
considered part of the api ('__magic__' names being a special case).
So it has nothing to do with data vs method dichotomy (which makes no
sens in a languages where functions and methods are objects), only with
API vs implementation. You choosed a crappy name for an attribute
that's part of the API, so it's *exactly* the same case as if you had
chosen a crappy name for a public method in Java. Think of public data
attributes as magical getter/setters with the most straightforward
behaviour, and of properties as the way to override this default behaviour.
Plus it's
really hard to choose crappy accessor name.
What about getMyCrappyAttributeName/setMyCrappyAttributeName ?-)
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
--
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Re: hash() yields different results for different platforms
Using Python's hash as column in the table might not be a good idea.
You just found out why. So you could instead just use the base url and
create an index based on that so next time just quickly get all urls
from same base address then do a linear search for a specific one, or
even easier, implement your own hashes without using any of the
Python's built-in hash() functions. For example, transform each
character to an int and multply them all mod 2^32-1 or something like
that. Even better I think someone already posted the Python's way of
generating hashes for string, well, just re-implement it in Python such
that your version will yield the same hash on any platform.
Hope this helps,
Nick V.
Qiangning Hong wrote:
I'm writing a spider. I have millions of urls in a table (mysql) to
check if a url has already been fetched. To check fast, I am
considering to add a hash column in the table, make it a unique key,
and use the following sql statement:
insert ignore into urls (url, hash) values (newurl, hash_of_newurl)
to add new url.
I believe this will be faster than making the url column unique key
and doing string comparation. Right?
However, when I come to Python's builtin hash() function, I found it
produces different values in my two computers! In a pentium4,
hash('a') - -468864544; in a amd64, hash('a') - 12416037344. Does
hash function depend on machine's word length?
If it does, I must consider another hash algorithm because the spider
will run concurrently in several computers, some are 32-bit, some are
64-bit. Is md5 a good choice? Will it be too slow that I have no
performance gain than using the url column directly as the unique
key?
I will do some benchmarking to find it out. But while making my hands
dirty, I would like to hear some advice from experts here. :)
--
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Re: Object Persistence Using a File System
Good point about isinstance. Here is a good explanation why:
http://www.canonical.org/~kragen/isinstance/
Also the frozenset should be added the list of immutable types.
Nick Vatamaniuc
Bruno Desthuilliers wrote:
Chris Spencer wrote:
Before I get too carried away with something that's probably
unnecessary, please allow me to throw around some ideas. I've been
looking for a method of transparent, scalable, and human-readable object
persistence, and I've tried the standard lib's Shelve, Zope's ZODB,
Divmod's Axiom, and others. However, while they're all useful, none
satisfies all my criteria. So I started writing some toy code of my own:
http://paste.plone.org/5227
All my code currently does is transparently keep track of object changes
without requiring any special coding on part of the user, and a function
to convert an object to a file system hierarchy of folders and files.
Please, let me know what you think.
As you say, using filesystem for fine-grained persistance may not be the
most efficient solution. I also wonder how (if...) you intend to address
concurrent R/W access and transactions...
A few observations and questions :
- you should avoid tests on concrete types as much as possible - at
least use isinstance
- tuples are immutable containers. What about them ?
- what about multiple references to a same object ?
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
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Re: What is a type error?
David Hopwood wrote: George Neuner wrote: All of this presupposes that you have a high level of confidence in the compiler. I've been in software development for going in 20 years now and worked 10 years on high performance, high availability systems. In all that time I have yet to meet a compiler ... or significant program of any kind ... that is without bugs, noticeable or not. [...] One of the main reasons for this, IMHO, is that many compilers place too much emphasis on low-level optimizations of dubious merit. For C and Java, I've taken to compiling all non-performance-critical code without optimizations, and that has significantly reduced the number of compiler bugs that I see. It has very little effect on overall execution performance (and compile times are quicker). I don't think that over-complex type systems are the cause of more than a small part of the compiler bug problem. In my estimation, the frequency of bugs in different compilers *for the same language* can vary by an order of magnitude. Also, the use of typed intermediate languages within the compiler might actually help drastically cutting down on the more severe problem of code transformation bugs, notwithstanding the relative complexity of suitable internal type systems. - Andreas -- http://mail.python.org/mailman/listinfo/python-list
Re: Accessors in Python (getters and setters)
Le mercredi 12 juillet 2006 11:17, mystilleef a écrit : Yes, it is possible to name crappy accessors too (e.g set_tmp/get_tmp). But developers tend to pay more attention to given methods/functions less crappy names, at least when compared to data attributes. Not python developers. This stems from the fact that in many languages data attributes aren't usually part of the API, as well as the whole OO(Encapsulation) blah blah. I know I would not name the accessors set_tmp/get_tmp, because my philosophy is that methods/functions need to have meaningful names and state their intended purpose. But that's not python philosophy. I don't hold data attributes to such standards and I imagine many developers don't either and least based on other people's code I've read. Plus there are many occassions when attributes are not intended to be APIs, but eventually become one. But they are in Python and that is the python's philosophy. All attribute or method not beginning with an '_' *is* API. After all most data attributes are created with the purpose of serving methods. And in python the reverse can be true : class a(object) : def __init__(self, ro_attr) : self.__attr = ro_attr def _getAttr(self) : A method which serves an attribute return self.__attr attr = property(_getAttr) -- _ Maric Michaud _ Aristote - www.aristote.info 3 place des tapis 69004 Lyon Tel: +33 426 880 097 -- http://mail.python.org/mailman/listinfo/python-list
Re: array of array of float
Schüle Daniel wrote: a = [[] for in range(200)] correction :) a = [[] for i in range(200)] the *500 part still seems to be missing... /F -- http://mail.python.org/mailman/listinfo/python-list
Re: hash() yields different results for different platforms
Grant Edwards [EMAIL PROTECTED] (GE) wrote: GE The low 32 bits match, so perhaps you should just use that GE portion of the returned hash? If the hashed should be unique, 32 bits is much too low if you have millions of entries. -- Piet van Oostrum [EMAIL PROTECTED] URL: http://www.cs.uu.nl/~piet [PGP 8DAE142BE17999C4] Private email: [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
RE: hash() yields different results for different platforms
The hash is not expected to be unique, it just provides a starting point for another search (usually linear ?). See http://en.wikipedia.org/wiki/Hash_function Helpfully, Maybe, Richard. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Piet van Oostrum Sent: 12 July 2006 10:56 To: python-list@python.org Subject: Re: hash() yields different results for different platforms Grant Edwards [EMAIL PROTECTED] (GE) wrote: GE The low 32 bits match, so perhaps you should just use that GE portion of the returned hash? If the hashed should be unique, 32 bits is much too low if you have millions of entries. -- Piet van Oostrum [EMAIL PROTECTED] URL: http://www.cs.uu.nl/~piet [PGP 8DAE142BE17999C4] Private email: [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Progress Bars in python
Hi, I've written a script which backs up a huge bunch of files, but I don't want the script to output the file names as it does this as it clutters the screen, I only output errors. So in order to see that the script is working and not stuck, I'd like to implement some kind of progress bar or something, perhaps like the spinning thing that you often see in linux or freebsd consisting of switching / - \ | on the spot to get the appearance of a spinning bar I can figure out that the spinning bar is done by switching these four chars but I don't know how they get each char to replace the last one instead of printing them in succession. Does anybody have any good suggestions about what the best way of doing this or any other suggestions for the best ways to show that the script is processing...? Hari -- http://mail.python.org/mailman/listinfo/python-list
Re: hash() yields different results for different platforms
Kerry, Richard [EMAIL PROTECTED] writes: The hash is not expected to be unique, it just provides a starting point for another search (usually linear ?). The database is good at organizing indexes and searching in them. Why not let the database do what it's good at. -- http://mail.python.org/mailman/listinfo/python-list
Re: Progress Bars in python
Hari Sekhon wrote: I've written a script which backs up a huge bunch of files, but I don't want the script to output the file names as it does this as it clutters the screen, I only output errors. So in order to see that the script is working and not stuck, I'd like to implement some kind of progress bar or something, perhaps like the spinning thing that you often see in linux or freebsd consisting of switching / - \ | on the spot to get the appearance of a spinning bar I can figure out that the spinning bar is done by switching these four chars but I don't know how they get each char to replace the last one instead of printing them in succession. use backspace (\b) or carriage return (\r) to move the cursor backwards. minimal example: import time, sys for i in range(100+1): sys.stdout.write(\r%c %d%% done... % (|/-\\[i%4], i)) sys.stdout.flush() time.sleep(0.2) maximal example (also see the comments): http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/473899 /F -- http://mail.python.org/mailman/listinfo/python-list
Re: timeit module for comparing the performance of two scripts
3c273 wrote: Doh! Me thinks Windows at work python /? (No good!) that was supposed to be fixed in 2.5, but it doesn't seem to have made it into beta 2. hmm. /F -- http://mail.python.org/mailman/listinfo/python-list
Re: I need some help
Tim Heaney wrote: Several different people have written modules to help you read (and write) ID3 tags. On a related topic, I have a Perl module that reads MP4/AAC tags - http://search.cpan.org/~jhar/MP4-Info/ - that I'm considering porting to Python. But before I start, is anyone aware of an existing Python module to read MP4/AAC tags? Jonathan. -- http://mail.python.org/mailman/listinfo/python-list
Re: How to terminate a main script?
Helmut Jarausch wrote: Hi, I'm still looking for an elegant and clear means to terminate the main script in Python. Unfortunately, Python doesn't allow a 'return' instruction in the main script. It is quite a common practice for Python scripts to define a main() function which contains the actual code, and have main() on the last line of the file. This allows you to just 'return' from wherever you like in your code. It is even more common to use this in the end instead of main(): if __name__ == __main__: main() This way, if the file is imported as a module, the main() function won't execute, but if it is run directly from a command line or using execfile() it will execute. Enjoy! - Tal -- http://mail.python.org/mailman/listinfo/python-list
Strange behaviour of Numeric Float32 array?
Hi, the code: from Numeric import * def my_minimum(a): n=shape(a)[0] x = 1.0e20 for i in range(n): if a[i] x: x = a[i] return x def strange(a): a[3] = -6303.0 h = my_minimum(a) for i in range(10): print i,a[i], a[i] = a[i] - h print a[i],h a = zeros(10,Float32) strange(a) b = zeros(10,Float64) strange(b) produces the output: 0 0.0 6303.0 -6303.0 1 0.0 6303.0 -6303.0 2 0.0 6303.0 -6303.0 3 -6303.0 0.0 0.0 4 0.0 0.0 0.0 5 0.0 0.0 0.0 6 0.0 0.0 0.0 7 0.0 0.0 0.0 8 0.0 0.0 0.0 9 0.0 0.0 0.0 0 0.0 6303.0 -6303.0 1 0.0 6303.0 -6303.0 2 0.0 6303.0 -6303.0 3 -6303.0 0.0 -6303.0 4 0.0 6303.0 -6303.0 5 0.0 6303.0 -6303.0 6 0.0 6303.0 -6303.0 7 0.0 6303.0 -6303.0 8 0.0 6303.0 -6303.0 9 0.0 6303.0 -6303.0 Can anybody tell me why in the Float32 version h is changed? Thank you in advance. Regards Rolf -- http://mail.python.org/mailman/listinfo/python-list
Re: Accessors in Python (getters and setters)
mystilleef wrote:
Lousy Attribute Name:
self.tmp
Accessors:
set_temporary_buffer
get_temporary_buffer
The attribute name I chose, tmp sucks.
Well, it's surely not as descriptive as 'temporary_buffer'
I have used that name in
dozens of places spanning over 27000 LOC.
Too bad for you.
There's a chance that other
develops might misinterpret exactly what tmp does. Plus I don't want
emails from other developers querying me about what tmp is/does.
tmp is obvious to me, but not necessarily to others.
So why did you name it that way at first ?
Now compare that
to the accessors.
But 'tmp' actually *is* an accessor.
Not only do they improve readability
Err... do you find:
obj.set_temporary_buffer(val)
val = obj.get_temporary_buffer()
really more readable than:
obj.temporary_buffer = val
val = obj.temporary_buffer
at the expense
of more code,
Indeed. In both the class and client code.
they actually allow me to change the lousily named
attribute tmp to temporary_buffer without grepping, seding,
searching, replacing and praying.
You still fail to get the point. You actually choose a crappy name for a
*public* property. It's *exactly* as if, in Java, you had named your
getter/setter 'get_tmp' and 'set_tmp'.
Sure, if you are dealing with less
than a 1000LOC you can get away with using tmp or renaming it easily.
But if you are dealing with a much larger code base and more
developers, issues like this rapidly become a nuisance.
Indeed. But it's *your* responsability to choose good names for the API.
Yes, it is possible to name crappy accessors too (e.g set_tmp/get_tmp).
or 'tmp'.
But developers tend to pay more attention to given methods/functions
less crappy names, at least when compared to data attributes.
s/developpers/you/
This
stems from the fact that in many languages data attributes aren't
usually part of the API,
Once again, in Python, there is *no* such thing as 'data attributes'.
*All* attributes are *objects* - some of them callable.
as well as the whole OO(Encapsulation) blah
blah.
Don't confuse encapsulation with data-hiding.
I know I would not name the accessors set_tmp/get_tmp, because my
philosophy is that methods/functions need to have meaningful names and
state their intended purpose.
That's true for each and every name in a program.
I don't hold data attributes to such
standards
Too bad for you.
and I imagine many developers don't either and least based on
other people's code I've read. Plus there are many occassions when
attributes are not intended to be APIs,
Then mark them as being implementation (ie : prefix them with a single
underscore).
but eventually become one.
After all most data attributes are created with the purpose of serving
methods.
Nope. You have the class API, and the class implementation. Both made of
both callable and non-callable attributes.
Mystilleef, I do share your pain (really - been here, done that,
etc...), and I understand that grasping Python requires some mental
adjustments when coming from Java and friends (been here, done that,
etc...). But you seriously can't blame the language for your own mistakes.
If you intented 'tmp' to be part of the API, then you're responsible for
the bad naming. If you didn't, then you're responsible for breaking the
encapsulation - FWIW, following the convention (single leading
underscore) could have make it clearer to you. In both cases, you
happily used a bad name in 27 KLOC - so you really had a lot of time and
occasions to notice something wrong with this.
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
--
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Re: Generating all ordered substrings of a string
[EMAIL PROTECTED] wrote: Hi, I want to generate all non-empty substrings of a string of length =2. Also, each substring is to be paired with 'string - substring' part and vice versa. Thus, ['abc'] gives me [['a', 'bc'], ['bc', 'a'], ['ab', 'c'], ['c', 'ab'], ['b', 'ac'], ['ac', 'b']] etc. Similarly, 'abcd' should give me [['a', 'bcd'], ['bcd', 'a'], ['abc', 'd'], ['d', 'abc'], ['b', 'acd'], ['acd', 'b'],['c', 'abd'], ['abd', 'c'], ['ab', 'cd'], ['cd', 'ab'], ['bc', 'ad'], ['ad', 'bc'], ['ac', 'bd'],['bd','ac']] In your last example you have ['ac','bd'], but neither 'ac' nor 'bd' is a _substring_ of 'abcd'. If you want to compute all possible (non-empty) sub-groups of a group (a group of characters, in your case), that's really quite a common algorthmic problem and you should be able to Google for a solution. Once you have all possible subgroups, just make your (weird) pairs, remove doubles (either by using a set or by sorting and removing identical neighboring objects), and you're done. If you're looking for a more efficient solution, specialized for your specific problem, you'll have to explain more precisely what you're trying to do, as well as why existing solutions aren't good enough. - Tal -- http://mail.python.org/mailman/listinfo/python-list
Last used directory?
Hello:
Is there a global or some trick I can use to have
Python remember the last directory visited?
What I mean is suppose I have this function:
def get_filename():
Returns a filename selected from a Tkinter File Selection Dialog
strFilename = tkFileDialog.askopenfilename(initialdir='.',
filetypes=[('Python
files','*.py'),
('All
Files','*.*')])
return strFilename
but instead of having initialdir='.' (current directory), I
would like it set to the last visited directory, which can be from a
previous run or even a previous day. Is that possible? If so how?
Thanks in advance:
Michael Yanowitz
--
http://mail.python.org/mailman/listinfo/python-list
Re: threading troubles
On 2006-07-10, sreekant [EMAIL PROTECTED] wrote:
Hi folks
What am I doing wrong in the following? I just want to run fluidsynth in
the background.
#
class MyThread(threading.Thread):
def __init__(self, cmd, callback):
self.__cmd = cmd
self.__callback = callback
threading.Thread.__init__(self)
def run(self):
os.system(self.__cmd)
self.__callback('abcd')
return
cmd=midiplay+' '+fmidi
xc=MyThread(cmd,addlog)
xc.start()
##
midiplay is 'fluidsynth -ni /home/mysndfont.sf2 mymidi.mid'
addlog is a function which prints the log.
If I run it only with xc.start() it does not run the program as in
os.system. However if I put
xc.start()
xc.run()
then it starts and runs it in foreground with my pygtk ui non responsive.
What am I missing!
You may be missing nothing. If I recall correctly a similar problem was
once reported on the pygtk-list. Some investigation showed that some
programs couldn't be reliably run from a thread, using os.system.
--
Antoon Pardon
--
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Re: Last used directory?
On Wed, 12 Jul 2006 07:29:18 -0400, Michael Yanowitz wrote: but instead of having initialdir='.' (current directory), I would like it set to the last visited directory, which can be from a previous run or even a previous day. Is that possible? If so how? Every time you open a file, save the directory in a global variable. Then instead of passing '.' as initialdir, pass that saved directory. That will work while you're in the same session. To remember the last visited directory from one session to the next, you'll need to write it to some sort of permanent storage like a configuration file. You'll also need to check what happens if the saved directory no longer exists. -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
Delivery failure notification
Your message with Subject: Important could not be delivered to the following recipients: [EMAIL PROTECTED] Please do not resend your original message. Delivery attempts will continue to be made for 4 day(s). -- http://mail.python.org/mailman/listinfo/python-list
Problems with Unicode Plane 1 characters on Windows
Hi all, Why doesn't the following code work on Windows XP, although it works on Linux (Ubuntu 6.06). Both versions are of Python are 2.4, and both OSs are on the same PC. import unicodedata unicodedata.name(U'\U0001d400') Traceback (most recent call last): File stdin, line 1, in ? TypeError: need a single Unicode character as parameter The output should say: MATHEMATICAL BOLD CAPITAL A Thanks, Edin -- http://mail.python.org/mailman/listinfo/python-list
Re: Progress Bars in python
Hari So in order to see that the script is working and not stuck, I'd Hari like to implement some kind of progress bar or something, ... Here's mine: http://orca.mojam.com/~skip/python/progress.py There are both Progress and Counter classes. Same idea, different output. Skip -- http://mail.python.org/mailman/listinfo/python-list
wxHtmlHelpController
is it possible to get the list of search results from the search box from wxPython's wxHtmlHelpControl without it displaying GUI? i don't see an obvious way to do this. thanks, bryan -- http://mail.python.org/mailman/listinfo/python-list
Re: wxHtmlHelpController
Bryan wrote: is it possible to get the list of search results from the search box from wxPython's wxHtmlHelpControl without it displaying GUI? i don't see an obvious way to do this. thanks, bryan i meant wxPython's wxHtmlHelpController -- http://mail.python.org/mailman/listinfo/python-list
Compiling Python using the Portland Group compiler
I am trying to install Python 2.4.3 on an AMD Opteron system using the Portland Group's compiler (pgcc). Using CC=pgcc -DNCURSES_ENABLE_STDBOOL_H=0 OPT=-O0 LINKFORSHARED=-Wl,- export-dynamic ./configure --without-cxx I finally managed to obtain an executable that would start and work, but it fails a couple of test cases: 1) test_coercion reports wrong results for operations with complex numbers. For example, 2**(2.+0j) yields (1+0j). 2) test_compare reports some wrong results, such as (2+0j) != (2+0j) However, typing (2+0j) == (2+0j) into the interpreter yields True. Perhaps the bug is in the execution of the test suite. 3) test_compile reports wrong results as well: test test_compile failed -- Traceback (most recent call last): File /work/experiences/biophys/hinsen/install/Python-2.4.3/Lib/ test/test_compile.py, line 164, in test_literals_with_leading_zeroes self.assertEqual(eval(0777j), 777j) AssertionError: 777j != 777j However, eval(0777j) == 777j yields True. 4) test_cpickle crashes with a segmentation fault. Has anyone encountered such failures before? Does anyone have useful suggestions for analyzing them? Konrad. -- - Konrad Hinsen Centre de Biophysique Moléculaire, CNRS Orléans Synchrotron Soleil - Division Expériences Saint Aubin - BP 48 91192 Gif sur Yvette Cedex, France Tel. +33-1 69 35 97 15 E-Mail: hinsen ät cnrs-orleans.fr - -- http://mail.python.org/mailman/listinfo/python-list
How to display name of elements in list?
Hi there, I'm sure there is a very simple solution for my question, I just didn't find it up to now. I'm using a badly documented module and therefore need to find out about how to access the elements in a list. (I need to do this in Python 1.5.3) Any help appreciated very much. Thanks! cz -- http://mail.python.org/mailman/listinfo/python-list
Re: How to display name of elements in list?
I'm using a badly documented module and therefore need to find out about how to access the elements in a list. (I need to do this in Python 1.5.3) I presume this is the same in 1.5 use dir(): import os dir(os) ['F_OK', 'O_APPEND', 'O_BINARY', 'O_CREAT', 'O_EXCL', 'O_NOINHERIT', 'O_RANDOM', 'O_RDONLY', 'O_RDWR', 'O_SEQUENTIAL', 'O_SHORT_LIVED', 'O_TEMPORARY', 'O_TEXT', (etc) -- http://mail.python.org/mailman/listinfo/python-list
Re: Accessors in Python (getters and setters)
Yes, it is possible to name crappy accessors too (e.g set_tmp/get_tmp). But developers tend to pay more attention to given methods/functions less crappy names, at least when compared to data attributes. This In my experience of getters and setters in Java, most developers choose attribute names first, and then use the IDE (Java without an IDE *really* sucks) to auto-generate the getters and setters. So most Java developers I have worked with pay more attention to attributes than accessor names as these are derived anyway. So I guess it depends on who the developers are ;-) -- http://mail.python.org/mailman/listinfo/python-list
Re: How to display name of elements in list?
On Wed, 12 Jul 2006 05:17:30 -0700, cz wrote: Hi there, I'm sure there is a very simple solution for my question, I just didn't find it up to now. I'm using a badly documented module and therefore need to find out about how to access the elements in a list. Er, the same way you would access the elements in any other list? mylist[0] mylist[1:5] etc. Perhaps you need to rephrase your question. -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
Re: first book about python
I recommend The Quick Python Book by Harms and McDonald. Its strength is its brevity and *readability* -- you can actually just sit down and read it and enjoy it. It doesn't cover the newest features of Python or the most advanced, but that is not necessary in a beginner's book. Once you're up to speed on Python, as a sysadmin you'll probably find Python Network Programming useful. It is not a beginner's book, but it is addressed to the kind of issues that you'll probably want to be using Python for. -- http://mail.python.org/mailman/listinfo/python-list
pygtk crashing when using gtkmozembed
hi all, I am trying to execute one simple program using pygtk-2.8.6 and gnome-python-extra-2.12.It's crashing at the time of executing the follwing instruction. - self.moz = gtkmozembed.MozEmbed() --- python is able to import the gtkmozembed module. plz help. Thanks, Moumita -- http://mail.python.org/mailman/listinfo/python-list
Re: How to display name of elements in list?
Perhaps you need to rephrase your question. -- Steven. Thanks for your reply. OK, I'll try to make this more clear: My list called elten looks like that: [Tensor: id = 1, intensity = 2976.52 xx = -1447.32, xy = 52.458, xz = -594.186 yy = -1090.54, yz = -0.0158068, zz = -4043. , Tensor: id = 26, intensity = 2896.9 ... , Tensor: id = 5, intensity = 2920.5 xx = -1534.53, xy = 23.4858, xz = -623.967 yy = -1070.47, yz = 99.6301, zz = -3979.87 ] Now with print elten[1].id I will get 1 as an answer. Or with print elten[1].intensity it will print 2976.52. But this doesn't work for print elten[1].xx, why? So that's how I came to the question how to access these values. Any idea? Thanks a lot! cz -- http://mail.python.org/mailman/listinfo/python-list
Re: How to display name of elements in list?
Hi Claudio, cz wrote: Perhaps you need to rephrase your question. -- Steven. Thanks for your reply. OK, I'll try to make this more clear: My list called elten looks like that: [Tensor: id = 1, intensity = 2976.52 xx = -1447.32, xy = 52.458, xz = -594.186 yy = -1090.54, yz = -0.0158068, zz = -4043. , Tensor: id = 26, intensity = 2896.9 ... , Tensor: id = 5, intensity = 2920.5 xx = -1534.53, xy = 23.4858, xz = -623.967 yy = -1070.47, yz = 99.6301, zz = -3979.87 ] Now with print elten[1].id I will get 1 as an answer. Or with print elten[1].intensity it will print 2976.52. But this doesn't work for print elten[1].xx, why? So that's how I came to the question how to access these values. Any idea? The list above is not a valid Python list. What is it that you store in that list? Or is it maybe a dictionary? Stefan -- http://mail.python.org/mailman/listinfo/python-list
Re: Multi-threaded FTP Question
Dennis Lee Bieber wrote: On 11 Jul 2006 06:45:42 -0700, [EMAIL PROTECTED] declaimed the following in comp.lang.python: Could it be that the SERVER is limiting things to 5 concurrent/parallel connections from any single IP? I know I've encountered sites that only allowed two FTP downloads at a time... This is what I was starting to think as well. The only thing that looked funky with the OP's code was that it looked like he was writing everything to a filename of (unless he's intentionally modified his code to not show where he's setting that). - Jeremy M. Jones -- http://mail.python.org/mailman/listinfo/python-list
Re: How to display name of elements in list?
The list above is not a valid Python list. What is it that you store in that list? Or is it maybe a dictionary? Stefan Thanks for your help. How can I find out about what this is? As I said it's generated by a insufficiently documented module. So if this is a user defined datatype, is there still a possibility to find the name of the data fields storing the xx, xy, ... ? Thanks. -- http://mail.python.org/mailman/listinfo/python-list
Re: Multi-threaded FTP Question
[EMAIL PROTECTED] wrote: I'm trying to use ftp in python in a multi-threaded way on a windows box - python version 2.4.3. Problem is that it appears that it's only possible to have five instances/threads at one point in time. Errors look like: File C:\Python24\lib\ftplib.py, line 107, in __init__ self.connect(host) File C:\Python24\lib\ftplib.py, line 132, in connect self.welcome = self.getresp() File C:\Python24\lib\ftplib.py, line 208, in getresp resp = self.getmultiline() File C:\Python24\lib\ftplib.py, line 194, in getmultiline line = self.getline() File C:\Python24\lib\ftplib.py, line 184, in getline if not line: raise EOFError EOFError Is it possible to have more than five simultaneous ftp connections? Thanks. Derek It might be XP SP2's worm protection as well: http://www.speedguide.net/read_articles.php?id=1497 -- http://mail.python.org/mailman/listinfo/python-list
Editing File
Hi, I currently have a Python app with a Tkinter GUI frontend that I use for system administration. Everytime it launches, it reads a text file which contains info about each host I wish to monitor - each field (such as IP, hostname, etc.) is delimited by !!. Now, I want to be able to edit host information from within the GUI - what would be the best way to go about this? Basically I just need to either edit the original host line, or write a new host line and delete the original..thanks! -- http://mail.python.org/mailman/listinfo/python-list
Re: What is a type error?
Marshall schrieb: Joachim Durchholz wrote: Marshall schrieb: Now, I'm not fully up to speed on DBC. The contract specifications, these are specified statically, but checked dynamically, is that right? That's how it's done in Eiffel, yes. In other words, we can consider contracts in light of inheritance, but the actual verification and checking happens at runtime, yes? Sure. Though, while DbC gives rules for inheritance (actually subtypes), these are irrelevant to the current discussion; DbC-minus-subtyping can still be usefully applied. Yes, subtyping. Of course I meant to say subtyping.blush No need to blush for that, it's perfectly OK in the Eiffel context, where a subclass ist always assumed to be a subtype. (This assumption isn't always true, which is why Eiffel has some serious holes in the type system. The DbC ideas are still useful though, saying subtype instead of subclass just makes the concept applicable outside of OO languages.) I can certainly see how DbC would be useful without subtyping. But would there still be a reason to separate preconditions from postconditions? I've never been clear on the point of differentiating them (beyond the fact that one's covariant and the other is contravariant.) There is indeed. The rules about covariance and contravariance are just consequences of the notion of having a subtype (albeit important ones when it comes to designing concrete interfaces). For example, if a precondition fails, something is wrong about the things that the subroutine assumes about its environment, so it shouldn't have been called. This means the error is in the caller, not in the subroutine that carries the precondition. The less important consequence is that this should be reflected in the error messages. The more important consequences apply when integrating software. If you have a well-tested library, it makes sense to switch off postcondition checking for the library routines, but not their precondition checking. This applies not just for run-time checking: Ideally, with compile-time inference, all postconditions can be inferred from the function's preconditions and their code. The results of that inference can easily be stored in the precompiled libraries. Preconditions, on the other hand, can only be verified by checking all places where the functions are called. Wouldn't it be possible to do them at compile time? (Although this raises decidability issues.) Exactly, and that's why you'd either uses a restricted assertion language (and essentially get something that's somewhere between a type system and traditional assertion); or you'd use some inference system and try to help it along (not a simple thing either - the components of such a system exist, but I'm not aware of any system that was designed for the average programmer). As to the average programmer, I heard this recently on comp.databases.theory: Don't blame me for the fact that competent programming, as I view it as an intellectual possibility, will be too difficult for the average programmer -you must not fall into the trap of rejecting a surgical technique because it is beyond the capabilities of the barber in his shop around the corner. -- EWD512 Given the fact that we have far more need for competently-written programs than for competent surgery, I don't think that we'll be able to follow that idea. Mightn't it also be possible to leave it up to the programmer whether a given contract was compile-time or runtime? I'd agree with that, but I'm not sure how well that would hold up in practice. I want to try it and see what it's like. So do I :-) Regards, Jo -- http://mail.python.org/mailman/listinfo/python-list
Re: Editing File
D wrote: Hi, I currently have a Python app with a Tkinter GUI frontend that I use for system administration. Everytime it launches, it reads a text file which contains info about each host I wish to monitor - each field (such as IP, hostname, etc.) is delimited by !!. Now, I want to be able to edit host information from within the GUI - what would be the best way to go about this? Basically I just need to either edit the original host line, or write a new host line and delete the original..thanks! I would create a data structure of the contents of the file and let the application reference that data structure. Sounds like it's going to be a list of lists or a list of dicts. Each line of the file is going to be an element of the main list. Each element of the list is going to be a dict or a list of the details of that particular host. Make it so that if your app changes the datastructure, you re-serialize it back to the file. This should work the same with adding a new host to monitor. It might be easier to use something like Yaml. I'm doing something similar with a little podcast grabber I'm working on. Here's some old code where I first incorporate using Yaml (down at the bottom of the page): http://jeremymjones.com/articles/simple-podcast-grabber-python/ The version I have in SVN right now creates a configgish object off of the Yaml and on re-assignment of either of the two main attributes, it automatically reserializes it. Anyway, hope this helps. - Jeremy M. Jones -- http://mail.python.org/mailman/listinfo/python-list
Re: How to display name of elements in list?
cz wrote: The list above is not a valid Python list. What is it that you store in that list? Or is it maybe a dictionary? Stefan Thanks for your help. How can I find out about what this is? As I said it's generated by a insufficiently documented module. So if this is a user defined datatype, is there still a possibility to find the name of the data fields storing the xx, xy, ... ? I guess the objects stored in the list have a __repr__-method overloaded that produces the text you see. What you should do is to install rlcompleter2, fire up a python prompt and write code that produces a list of your objects. Then you can play around with the objects and utilize the reflection capabilities of python, which are conveniently exposed using rlcompleter2. Another option is to look into the source of that module and identify the objects created. Documentation is overrated - use the source, Luke! Diez -- http://mail.python.org/mailman/listinfo/python-list
Re: How to display name of elements in list?
My list called elten looks like that: [Tensor: id = 1, intensity = 2976.52 xx = -1447.32, xy = 52.458, xz = -594.186 yy = -1090.54, yz = -0.0158068, zz = -4043. , Tensor: id = 26, intensity = 2896.9 ... , Tensor: id = 5, intensity = 2920.5 xx = -1534.53, xy = 23.4858, xz = -623.967 yy = -1070.47, yz = 99.6301, zz = -3979.87 ] The list above is not a valid Python list. What is it that you store in that list? It might well be a normal Python list. The question is what type the items in the list are... The result of printing a list L is basically a string you could make like this: '[' + ','.join(map(repr,L)) + ']' It seems the elements in this list appear as something like this when you apply the repr() function on them: Tensor: id = 1, intensity = 2976.52 xx = -1447.32, xy = 52.458, xz = -594.186 yy = -1090.54, yz = -0.0158068, zz = -4043. So, the issue is not how you work with a list, but how you work with the elements of this type. To reduce the problem to that, you can assign the first element in the list to a variable. elem0 = elten[0] Then you can inspect that in isolation, without the confusion of the list. type(elem0) dir(elem0) etc... -- http://mail.python.org/mailman/listinfo/python-list
Re: How to display name of elements in list?
cz schrieb: The list above is not a valid Python list. What is it that you store in that list? Or is it maybe a dictionary? Stefan Thanks for your help. How can I find out about what this is? As I said it's generated by a insufficiently documented module. So if this is a user defined datatype, is there still a possibility to find the name of the data fields storing the xx, xy, ... ? Maybe you should read a bit about Python classes and built-in functions like dir(), type(), vars(), ... http://docs.python.org/tut/node8.html#SECTION00830 http://docs.python.org/tut/node11.html http://docs.python.org/lib/built-in-funcs.html Just start an interactive Python session and play with the object you are trying to explore. That should get you going. Stefan -- http://mail.python.org/mailman/listinfo/python-list
Re: hash() yields different results for different platforms
On 2006-07-12, Carl Banks [EMAIL PROTECTED] wrote: Grant Edwards wrote: On 2006-07-11, Qiangning Hong [EMAIL PROTECTED] wrote: I'm writing a spider. I have millions of urls in a table (mysql) to check if a url has already been fetched. To check fast, I am considering to add a hash column in the table, make it a unique key, and use the following sql statement: insert ignore into urls (url, hash) values (newurl, hash_of_newurl) to add new url. I believe this will be faster than making the url column unique key and doing string comparation. Right? I doubt it will be significantly faster. Comparing two strings and hashing a string are both O(N). Playing Devil's Advocate: The hash would be a one-time operation during database insertion, whereas string comparison would happen every search. Good point. Conceivably, comparing hash strings (which is O(1)) could result in a big savings compared to comparing regular strings; Still, I doubt that the URLs are long enough so that there's a significant difference. but I expect most decent sql implementations already hash data internally, so rolling your own hash would be useless at best. Precisely. DB designers and implementers have been working on this problem for 30 years. I doubt the OP is going to be able to best them with a few minutes work. If the OP's database is lacking, md5 is probably fine. Perhaps using a subset of the md5 (the low 32 bits, say) could speed up comparisons at risk of more collisions. Probably a good trade off unless the DB is humungous. My advice: do it the simple way first (let the DB handle it). Don't try to fix a problem until you know it exists. Premature optimization -- Grant Edwards grante Yow! It's strange, but I'm at only TRULY ALIVE when I'm visi.comcovered in POLKA DOTS and TACO SAUCE... -- http://mail.python.org/mailman/listinfo/python-list
Re: hash() yields different results for different platforms
On 2006-07-12, Qiangning Hong [EMAIL PROTECTED] wrote:
Grant Edwards wrote:
On 2006-07-11, Qiangning Hong [EMAIL PROTECTED] wrote:
However, when I come to Python's builtin hash() function, I
found it produces different values in my two computers! In a
pentium4, hash('a') - -468864544; in a amd64, hash('a') -
12416037344. Does hash function depend on machine's word
length?
Apparently. :)
The low 32 bits match, so perhaps you should just use that
portion of the returned hash?
hex(12416037344)
'0x2E40DB1E0L'
hex(-468864544 0x)
'0xE40DB1E0L'
hex(12416037344 0x)
'0xE40DB1E0L'
hex(-468864544 0x)
'0xE40DB1E0L'
Is this relationship (same low 32 bits) guaranteed?
No, I don't believe so.
Will it change in the future version?
It may.
--
Grant Edwards grante Yow! Is this an out-take
at from the BRADY BUNCH?
visi.com
--
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Re: What is a type error?
Darren New schrieb: As far as I understand it, Eiffel compilers don't even make use of postconditions to optimize code or eliminate run-time checks (like null pointer testing). That's correct. I think a large part of the reasons why this isn't done is that Eiffel's semantics is (a) too complicated (it's an imperative language after all), and (b) not formalized, which makes it difficult to assess what optimizations are safe and what aren't. (Reason (c) is that Eiffel compiler vendors don't have the manpower for this kind of work, mostly in quantity but also, to some degree, in quality: people with a solid language semantics background tend to be repelled by the language inventor's know-it-all deny-the-problems don't-bother-me-with-formalisms attitude. He still has moved the state of the art ahead - mostly by pointing out a certain class of problems in OO designs and explaining them lucidly, and proposing solutions that hold up better than average even if still fundamentally flawed.) Regards, Jo -- http://mail.python.org/mailman/listinfo/python-list
Re: Sets and Membership Tests
Thanks for the advice. Once assured that __hash__ etc was the right route, I found that using hash() instead of object.__hash__() gave me stable hash valules. (I am hashing strings that I know to be unique.) The no luck situation was that a set would accept the same object multiple times, not recognizing that it was truly the same object. Nick Vatamaniuc wrote: JK, You are correct to implement __hash__ and __eq__. The problem is how you implemented them. Usually your __eq__ method should compare the necessary attributes of the objects for equality. The __hash__ should return a 32-bit integer. Your best bet is probably to return a hash of hashes of your attributes that are used in equality comparison. What this means is that your attributes used to produce the __hash__ should also be hashable. This is important yet not immediatly obvious. So you could for example return hash( (attribute1, attribute2, attribute3) ), where attribute1, attribute2, attribute3 are all hashable. Of course, you provided no code and no error messages (the 'SoFarNoLuck' exception is not descriptive enough ; ) Hope this helps JKPeck wrote: I would like to be able use sets where the set members are objects of a class I wrote. I want the members to be distinguished by some of the object content, but I have not figured out how a set determines whether two (potential) elements are identical. I tried implementing __eq__ and __ne__ and __hash__ to make objects with identical content behave as identical for set membership, but so far no luck. I could subclass set if necessary, but I still don't know what I would need to override. TIA for any advice you can offer. -- http://mail.python.org/mailman/listinfo/python-list
Data access from multiple code modules
Lets say that I have an application consisting of 3 files. A main.py file, gui.py and a data.py which handles persistent data storage. Suppose data.py defines a class 'MyDB' which reads in data from a database, and main.py creates an instance of this object. How does code in gui.py access this object? Here's simplified pseudocode: MAIN.PY import gui, data DataObject = data.MyDB(blah) How do I write code in gui.py that can access DataObject? Is this entirely the wrong way to approach this sort of problem? Actualy the problem is more complex because the GUI consists of a main GUI form, and panels defined as seperate objects in seperate files. Various panels will contain controlls for manipulating data in the DataObject, or wherever data storage end up. Best regards, Simon Hibbs (who strugles to get his head round this OOP stuff sometimes). -- http://mail.python.org/mailman/listinfo/python-list
Re: Data access from multiple code modules
[EMAIL PROTECTED] wrote: Lets say that I have an application consisting of 3 files. A main.py file, gui.py and a data.py which handles persistent data storage. Suppose data.py defines a class 'MyDB' which reads in data from a database, and main.py creates an instance of this object. How does code in gui.py access this object? Here's simplified pseudocode: MAIN.PY import gui, data DataObject = data.MyDB(blah) How do I write code in gui.py that can access DataObject? Is this entirely the wrong way to approach this sort of problem? Actualy the problem is more complex because the GUI consists of a main GUI form, and panels defined as seperate objects in seperate files. Various panels will contain controlls for manipulating data in the DataObject, or wherever data storage end up. What does main.py do? Are you creating an instance of the gui thingy? If so, you could just pass DataObject into your gui thingy either into the constructor or to a setter once you create an instance of it. If the gui needs any database stuff at instantiation time, you probably need to pass it into the constructor. However, a main.py, gui.py, and db.py smells a little like your standard MVC, in which case, you would get your controller to pass in the data pieces as the GUI needs them. - Jeremy M. Jones -- http://mail.python.org/mailman/listinfo/python-list
Re: Sets and Membership Tests
JKPeck [EMAIL PROTECTED] wrote: Thanks for the advice. Once assured that __hash__ etc was the right route, I found that using hash() instead of object.__hash__() gave me stable hash valules. (I am hashing strings that I know to be unique.) The no luck situation was that a set would accept the same object multiple times, not recognizing that it was truly the same object. Your problem may have been exactly that you were misunderstanding the nature and functionality of object.__hash__: x='guess what' id(x) 360720 object.__hash__(x) 360720 As you see, what it does is return the id() of the object (that's how objects are hashed -- if they don't implement __eq__ or __cmp__, equality comparisons also go to the id()'s, so things work;-) -- unless their type/class overrides __hash__). Of course, by going directly to object.__hash__ you're explicitly *avoiding* the override, so... Alex -- http://mail.python.org/mailman/listinfo/python-list
Re: Progress Bars in python
On 12/07/06, Fredrik Lundh [EMAIL PROTECTED] wrote: If the output of the script is sent to a logfile, this tends to puke all over the logfile... creating one additional entry per iteration, but it's a good start and I'll look at that link which looks very promising. there's no way to do this without sending more stuff to stdout than yousee; however, it's easy to *disable* the spinner if you're redirecting theoutput.hint:$ python -c import sys; print sys.stdout.isatty ()True$ python -c import sys; print sys.stdout.isatty() out$ more outFalse/FThanks, that will do nicely. It will be sufficient to do this testing using isatty() and have the progress bar or spinner. -h -- http://mail.python.org/mailman/listinfo/python-list
Re: Editing File
D wrote: Hi, I currently have a Python app with a Tkinter GUI frontend that I use for system administration. Everytime it launches, it reads a text file which contains info about each host I wish to monitor - each field (such as IP, hostname, etc.) is delimited by !!. Now, I want to be able to edit host information from within the GUI - what would be the best way to go about this? Basically I just need to either edit the original host line, or write a new host line and delete the original..thanks! Might be overkill - but pickle the data memeber that contains the information. If you use text instead of binary pickling it should still be editable by hand. for a single line of text it may be a bit much - but it's still probably quicker than opening a file, parsing etc. -- http://mail.python.org/mailman/listinfo/python-list
Re: Data access from multiple code modules
[EMAIL PROTECTED] wrote:
Lets say that I have an application consisting of 3 files. A main.py
file, gui.py and a data.py which handles persistent data storage.
Suppose data.py defines a class 'MyDB' which reads in data from a
database, and main.py creates an instance of this object. How does code
in gui.py access this object?
Obviously, you need to pass whatever relevant to this code...
Here's simplified pseudocode:
MAIN.PY
import gui, data
DataObject = data.MyDB(blah)
How do I write code in gui.py that can access DataObject?
Passing DataObject to code in guy.py seems like a very straightforward
solution...
Is this
entirely the wrong way to approach this sort of problem?
Actualy the problem is more complex because the GUI consists of a main
GUI form, and panels defined as seperate objects in seperate files.
Various panels will contain controlls for manipulating data in the
DataObject, or wherever data storage end up.
Hmmm... Hard to tell without seeing the code (and I've not done GUI
programmer for a long time), but putting application logic in the GUI is
usually a bad idea IME. Better to put the application logic in a
separate controler (that has a reference to the model - here your
DataObject), and have the GUI part call on the controler.
Best regards,
Simon Hibbs
(who strugles to get his head round this OOP stuff sometimes).
Well, actually one can do MVC without OO. It's more a matter of
separating concerns. Now I agree that it's not always obvious to know
for sure which part should be responsible for what...
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
--
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Persistant dictionary with lockable elements
Hi, I'd like to have a persistant dictionary in a server so that incoming requests acquire a specific Python object, do something with it then return. There wont be that many objects but it is the persistance that is important here, I want the information to survive server re-starts / crashes. The Shelve module seems ideal for this, but because the server will be multithreaded I would like to be able to lock individual elements of the shelve while they are being processed (not just the entire Shelve object). Is there some way of using Shelve like this, or should I just move to a more typical database solution? Thanks, Will McGugan http://www.willmcgugan.com -- http://mail.python.org/mailman/listinfo/python-list
Re: Progress Bars in python
Hari Sekhon wrote: Hi, I've written a script which backs up a huge bunch of files, but I don't want the script to output the file names as it does this as it clutters the screen, I only output errors. So in order to see that the script is working and not stuck, I'd like to implement some kind of progress bar or something, perhaps like the spinning thing that you often see in linux or freebsd consisting of switching / - \ | on the spot to get the appearance of a spinning bar I can figure out that the spinning bar is done by switching these four chars but I don't know how they get each char to replace the last one instead of printing them in succession. Does anybody have any good suggestions about what the best way of doing this or any other suggestions for the best ways to show that the script is processing...? Hari This also is shown in Python Cookbook: http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/299207 Larry Bates -- http://mail.python.org/mailman/listinfo/python-list
Re: How to display name of elements in list?
Stefan Behnel wrote: The list above is not a valid Python list. there's no Python 1.5.3 either. maybe he's posting from a parallel, slightly different universe ? /F -- http://mail.python.org/mailman/listinfo/python-list
Re: Persistant dictionary with lockable elements
Will McGugan wrote:
Hi,
I'd like to have a persistant dictionary in a server so that incoming
requests acquire a specific Python object, do something with it then
return. There wont be that many objects but it is the persistance that
is important here, I want the information to survive server re-starts /
crashes. The Shelve module seems ideal for this, but because the server
will be multithreaded I would like to be able to lock individual
elements of the shelve while they are being processed (not just the
entire Shelve object).
Is there some way of using Shelve like this, or should I just move to a
more typical database solution?
You may want to try with the ZODB. Or with SQLite.
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
--
http://mail.python.org/mailman/listinfo/python-list
Re: Data access from multiple code modules
Jeremy Jones wrote: What does main.py do? Are you creating an instance of the gui thingy? If so, you could just pass DataObject into your gui thingy either into the constructor or to a setter once you create an instance of it. It's a wxPython app. I created the GUI initialy using wxGlade which gave me a small myapp.py script, a file containing the main application frame (containing a listbook controll) and several files containing panel classes. Each panel class contains controlls for performing various operations on the data set (adding records, deleting them, running various transformations). I can't say I understand how it all works at a deep level, although I've been hacking it about quite successfuly so far. Presumably if I pass DataObject through to the Frame object, and from there through to the Panel objects then presumably this will solve the probelm? I guess it would be passed by reference so all the panels would be working on the same data object? Doh! How simple. Why didn't I think of that? I'm too used to procedural scripts where you'd just put everything in a global data structure. I know this is bad, but it's hard to get out of that mentality. Many thanks, Simon Hibbs P.S. Regular reader of your blog on Oreillynet. -- http://mail.python.org/mailman/listinfo/python-list
Re: Problems with Unicode Plane 1 characters on Windows
Edin Salković wrote: Why doesn't the following code work on Windows XP, although it works on Linux (Ubuntu 6.06). Both versions are of Python are 2.4, and both OSs are on the same PC. import unicodedata unicodedata.name(U'\U0001d400') Traceback (most recent call last): File stdin, line 1, in ? TypeError: need a single Unicode character as parameter The output should say: MATHEMATICAL BOLD CAPITAL A hint: len(u'\U0001d400') 2 Python's Unicode system uses 16-bit values internally on some platforms, and 32-bit values on some platforms. on 16-bit platforms, code points outside the BMP are stored as surrogate pairs. also see: http://pyref.infogami.com/type-unicode /F -- http://mail.python.org/mailman/listinfo/python-list
Re: Editing File
Thanks, guys. So overall, would it just be easier (and not too rigged) if any changes were made by just editing the text file? I want to do this project the right way, but if it's going to be a big pain to implement the edit function, just modifying the text file directly isn't that big of a deal.. [EMAIL PROTECTED] wrote: D wrote: Hi, I currently have a Python app with a Tkinter GUI frontend that I use for system administration. Everytime it launches, it reads a text file which contains info about each host I wish to monitor - each field (such as IP, hostname, etc.) is delimited by !!. Now, I want to be able to edit host information from within the GUI - what would be the best way to go about this? Basically I just need to either edit the original host line, or write a new host line and delete the original..thanks! Might be overkill - but pickle the data memeber that contains the information. If you use text instead of binary pickling it should still be editable by hand. for a single line of text it may be a bit much - but it's still probably quicker than opening a file, parsing etc. -- http://mail.python.org/mailman/listinfo/python-list
Re: Editing File
D wrote: Thanks, guys. So overall, would it just be easier (and not too rigged) if any changes were made by just editing the text file? I want to do this project the right way, but if it's going to be a big pain to implement the edit function, just modifying the text file directly isn't that big of a deal.. have you used pickle? if the data is as simple as you say it is, you will be able to read the pickle file. 2nd, it will be a lot less code really. You just load and unpickle the file into a variable. After any edit in the gui, repickle it to the same file. You would have to do the same if you edited the text file, except you would need a couple of lines code to parse the string, etc. check here for a simple example : http://wiki.python.org/moin/UsingPickle [EMAIL PROTECTED] wrote: D wrote: Hi, I currently have a Python app with a Tkinter GUI frontend that I use for system administration. Everytime it launches, it reads a text file which contains info about each host I wish to monitor - each field (such as IP, hostname, etc.) is delimited by !!. Now, I want to be able to edit host information from within the GUI - what would be the best way to go about this? Basically I just need to either edit the original host line, or write a new host line and delete the original..thanks! Might be overkill - but pickle the data memeber that contains the information. If you use text instead of binary pickling it should still be editable by hand. for a single line of text it may be a bit much - but it's still probably quicker than opening a file, parsing etc. -- http://mail.python.org/mailman/listinfo/python-list
check type when assignment
Hello everyone: Is there a way to check the type when do assignment? if I write: ab = bc and want to make sure the return value of isinstance(bc, klass) is True or I will raise a exception. Any suggestion? -- http://mail.python.org/mailman/listinfo/python-list
Re: How to display name of elements in list?
Diez B. Roggisch deets at nospam.web.de writes: What you should do is to install rlcompleter2... [snip] Another option is to look into the source of that module and identify the objects created. Documentation is overrated - use the source, Luke! rlcompleter is overrated, and only works on Unix/Linux/etc. IDLE's interpreter has an auto-completion extension, which is bundled in Python2.5. You can also get a much better version of IDLE which includes a more robust version of the completion extension from Idle-Spoon: http://idlespoon.python-hosting.com/ stefan writes: Just start an interactive Python session and play with the object you are trying to explore. That should get you going. +1 Python is fun - just open an interpreter and play around! - Tal -- http://mail.python.org/mailman/listinfo/python-list
Re: Editing File
D wrote: Thanks, guys. So overall, would it just be easier (and not too rigged) if any changes were made by just editing the text file? I want to do snip [EMAIL PROTECTED] wrote: snip Might be overkill - but pickle the data memeber that contains the information. If you use text instead of binary pickling it should still be editable by hand. for a single line of text it may be a bit much - but it's still probably quicker than opening a file, parsing etc. Look at pickle, but I'd recommend against it if you're anticipating needing to edit the file by hand. It's just a little on the ugly side. Glance at Yaml (I think it's the pyyaml project in the cheeseshop) as well. Here's the code needed to parse in a .yaml file: config = yaml.load(open(self.config_file, r)) Here's the code needed to serialize it back in a pretty format: yaml.dump(config, config_file_obj, default_flow_style=False) And here's a piece of a .yaml file itself: feeds: http://leo.am/podcasts/floss: name: FLOSS Weekly mode: dl http://revision3.com/diggnation/feed/high.mp3.xml: name: Revision3 - Diggnation w/Kevin Rose Alex Albrecht mode: dl http://geekmuse.net/podcast/: name: Geek Muse mode: dl http://www.itconversations.com/rss/category-rss.php?k=achange2005e=1: name: Accelerating Change 2005 mode: dl Nice and clean. - Jeremy M. Jones -- http://mail.python.org/mailman/listinfo/python-list
Re: Data access from multiple code modules
[EMAIL PROTECTED] wrote: snip Doh! How simple. Why didn't I think of that? I'm too used to procedural scripts where you'd just put everything in a global data structure. I know this is bad, but it's hard to get out of that mentality. Sounds like you got it. Just pass it on down as needed. - jmj -- http://mail.python.org/mailman/listinfo/python-list
Re: timeit module for comparing the performance of two scripts
3c273 wrote: John Machin [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] You appear to know what a switch is. I'm therefore surprised that you appear not to know that the convention is that any program that uses command-line switches should do something informative when run with a -h switch. Doh! Me thinks Windows at work python /? (No good!), Linux at home python -h (Ah ha!). I still think it should be in the docs somewhere. python /? now works in 2.5 SVN. Georg -- http://mail.python.org/mailman/listinfo/python-list
Re: check type when assignment
pipehappy pipehappy at gmail.com writes: Hello everyone: Is there a way to check the type when do assignment? if I write: ab = bc and want to make sure the return value of isinstance(bc, klass) is True or I will raise a exception. Any suggestion? 1. Check your condition before the assignment: (IMO one-liners are over-rated) if not isinstance(bc, klass): raise TypeError # or do whatever else is appropriate ab = bc 2. If you really insist on doing this in a single statement (in the assignment itself), write a function for it: def assert_type(obj, klass): if not isinstance(bc, klass): raise TypeError return obj ab = assert_type(bc, klass) Or to be more generic: def assert_return(obj, func): assert func(obj) return obj ab = assert_return(bc, lambda obj:isinstance(obj, klass)) - Tal -- http://mail.python.org/mailman/listinfo/python-list
don't need dictionary's keys - hash table?
Hello, I am using some very large dictionaries with keys that are long strings (urls). For a large dictionary these keys start to take up a significant amount of memory. I do not need access to these keys -- I only need to be able to retrieve the value associated with a certain key, so I do not want to have the keys stored in memory. Could I just hash() the url strings first and use the resulting integer as the key? I think what I'm after here is more like a tradition hash table. If I do it this way am I going to get the memory savings I am after? Will the hash function always generate unique keys? Also, would the same technique work for a set? Any other thoughts or considerations are appreciated. Thank You. -- http://mail.python.org/mailman/listinfo/python-list
Re: check type when assignment
pipehappy wrote: Hello everyone: Is there a way to check the type when do assignment? if I write: ab = bc and want to make sure the return value of isinstance(bc, klass) is True or I will raise a exception. In general, not doable. The assignment operator is not overloadable. Only if you use assignments of the form a.foo = bar you could overwrite the __setattribute__-method to achieve what you want. Diez -- http://mail.python.org/mailman/listinfo/python-list
Re: How to display name of elements in list?
rlcompleter is overrated, and only works on Unix/Linux/etc. IDLE's interpreter has an auto-completion extension, which is bundled in Python2.5. I don't use idle, and don't want to. So for me rlcomlpeter2 is a good thing. And under windows, it at least works under cygwin. Diez -- http://mail.python.org/mailman/listinfo/python-list
Re: Editing File
akameswaran at gmail.com akameswaran at gmail.com writes: D wrote: Thanks, guys. So overall, would it just be easier (and not too rigged) if any changes were made by just editing the text file? [snip] have you used pickle? if the data is as simple as you say it is, you will be able to read the pickle file. 2nd, it will be a lot less code really. You just load and unpickle the file into a variable. After any edit in the gui, repickle it to the same file. You would have to do the same if you edited the text file, except you would need a couple of lines code to parse the string, etc. If you don't plan to edit your data by hand, Pickle is a nice and simple choice. To save you from coding the persistency bits, you can use Python's built-in shelve module. Shelve uses Pickle to serialize Python objects but it does most of the persistency stuff for you. It is very simple and clean to use. One nice feature is that can open a shelve in auto-writeback mode, so upon assignment to one of the shelve's keys (it's like a dict) the shelve is automatically re-serialized to the file on disk. This saves headaches like remembering to serialize the data upon exit cleanup, crashes resulting in data loss, etc. Shelve is the simplest tool I know of. YAML sounds nice and readable, I haven't tryed it out yet. You could use XML easily enough with ElementTree. Good luck! - Tal -- http://mail.python.org/mailman/listinfo/python-list
Re: Editing File
Le mercredi 12 juillet 2006 17:00, D a écrit :
Thanks, guys. So overall, would it just be easier (and not too rigged)
if any changes were made by just editing the text file? I want to do
this project the right way, but if it's going to be a big pain to
implement the edit function, just modifying the text file directly
isn't that big of a deal..
If you don't want to rely on third party libraries, and want a human-readable
format I'll suggest using csv file format :
and this way ?
In [47]: class Z(object) :
: def __init__(self, val) : self.val = val
:
:
In [48]: lst = [Z(i) for i in range(2) + [ str(e) for e in range(2) ] ]
In [49]: [ (e, e.val) for e in lst ]
Out[49]:
[(__main__.Z object at 0xa76c252c, 0),
(__main__.Z object at 0xa76c27ac, 1),
(__main__.Z object at 0xa76c23ac, '0'),
(__main__.Z object at 0xa76c23ec, '1')]
In [51]: csv.writer(file('config.csv', 'w')).writerows([
(type(i.val).__name__, i.val) for i in lst])
In [52]: print file('config.csv').read()
int,0
int,1
str,0
str,1
In [53]: l = [ Z(eval(class_)(val)) for class_, val in
csv.reader(file('config.csv')) ]
In [54]: [ (e, e.val) for e in l ]
Out[54]:
[(__main__.Z object at 0xa76c218c, 0),
(__main__.Z object at 0xa76c260c, 1),
(__main__.Z object at 0xa76c256c, '0'),
(__main__.Z object at 0xa76c25cc, '1')]
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Aristote - www.aristote.info
3 place des tapis
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Tel: +33 426 880 097
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Re: Multi-threaded FTP Question
Thanks so much for your help on this. The server that I'm connecting to is the culprit. They only allow five connections at a time. I assumed that it was a code issue. I think that we're conditioned to expect that the problem is on the software side of things. -Derek [EMAIL PROTECTED] wrote: [EMAIL PROTECTED] wrote: I'm trying to use ftp in python in a multi-threaded way on a windows box - python version 2.4.3. Problem is that it appears that it's only possible to have five instances/threads at one point in time. Errors look like: File C:\Python24\lib\ftplib.py, line 107, in __init__ self.connect(host) File C:\Python24\lib\ftplib.py, line 132, in connect self.welcome = self.getresp() File C:\Python24\lib\ftplib.py, line 208, in getresp resp = self.getmultiline() File C:\Python24\lib\ftplib.py, line 194, in getmultiline line = self.getline() File C:\Python24\lib\ftplib.py, line 184, in getline if not line: raise EOFError EOFError Is it possible to have more than five simultaneous ftp connections? Thanks. Derek It might be XP SP2's worm protection as well: http://www.speedguide.net/read_articles.php?id=1497 -- http://mail.python.org/mailman/listinfo/python-list
Re: don't need dictionary's keys - hash table?
[EMAIL PROTECTED] wrote: Hello, I am using some very large dictionaries with keys that are long strings (urls). For a large dictionary these keys start to take up a significant amount of memory. I do not need access to these keys -- I only need to be able to retrieve the value associated with a certain key, so I do not want to have the keys stored in memory. Could I just hash() the url strings first and use the resulting integer as the key? I think what I'm after here is more like a tradition hash table. If I do it this way am I going to get the memory savings I am after? Will the hash function always generate unique keys? Also, would the same technique work for a set? I just realized that of course the hash is not always going to be unique, so this wouldn't really work. And it seems a hash table would still need to store the keys (as strings) so that string comparisons can be done when a collision occurs. I guess there's no avoiding storing they keys? -- http://mail.python.org/mailman/listinfo/python-list
Re: Data access from multiple code modules
[EMAIL PROTECTED] wrote:
Jeremy Jones wrote:
What does main.py do? Are you creating an instance of the gui thingy?
If so, you could just pass DataObject into your gui thingy either into
the constructor or to a setter once you create an instance of it.
It's a wxPython app. I created the GUI initialy using wxGlade which
gave me a small myapp.py script, a file containing the main application
frame (containing a listbook controll) and several files containing
panel classes. Each panel class contains controlls for performing
various operations on the data set (adding records, deleting them,
running various transformations).
Do you mean the code effectively doing these operations is in the gui ?
If yes, it would be better to factor it out IMHO.
I can't say I understand how it all
works at a deep level,
although I've been hacking it about quite
successfuly so far.
Presumably if I pass DataObject through to the Frame object, and from
there through to the Panel objects then presumably this will solve the
probelm?
Presumably !-)
I guess it would be passed by reference so all the panels
would be working on the same data object?
Python doesn't really have a pass by value semantic, since variables
are really just names bound to (ie : refering to) objects. So when it
comes to arguments passing, the argument *name* is local to the function
(rebinding the name won't affect the binding in the caller's namespace),
but what's bound to the name is really a reference to the object (so
mutating the object will effectively affect it).
Doh! How simple. Why didn't I think of that? I'm too used to procedural
scripts where you'd just put everything in a global data structure. I
know this is bad,
Well, depends on the size of the script. But it sure doesn't scale !-)
And FWIW, even with procedural, it's possible (and usually better) to
pass arguments around instead of having a big global datastructure.
Classes are handy when many functions needs to share state (work on a
same dataset), but there's no way to have one call the other and pass it
the dataset.
but it's hard to get out of that mentality.
Seems you're on the right way !-)
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python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
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Re: check type when assignment
Diez B. Roggisch wrote:
pipehappy wrote:
Hello everyone:
Is there a way to check the type when do assignment?
if I write:
ab = bc
and want to make sure the return value of isinstance(bc, klass) is True
or I will raise
a exception.
In general, not doable. The assignment operator is not overloadable.
Only if you use assignments of the form
a.foo = bar
you could overwrite the __setattribute__-method
(Or use a Descriptor)
to achieve what you want.
Diez
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
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Re: Sets and Membership Tests
JK, As a general rule, let Python call the magic __method__ methods behind the scenes. So don't call obj.__hash()__ or obj.__len__ or obj.__le__ just use hash(obj), len(obj) or =. Of course there are exceptions, for example when calling the __init__() method of a supercalass inside the __init__ method of your class and perhaps a few others... Nick V. JKPeck wrote: Thanks for the advice. Once assured that __hash__ etc was the right route, I found that using hash() instead of object.__hash__() gave me stable hash valules. (I am hashing strings that I know to be unique.) The no luck situation was that a set would accept the same object multiple times, not recognizing that it was truly the same object. Nick Vatamaniuc wrote: JK, You are correct to implement __hash__ and __eq__. The problem is how you implemented them. Usually your __eq__ method should compare the necessary attributes of the objects for equality. The __hash__ should return a 32-bit integer. Your best bet is probably to return a hash of hashes of your attributes that are used in equality comparison. What this means is that your attributes used to produce the __hash__ should also be hashable. This is important yet not immediatly obvious. So you could for example return hash( (attribute1, attribute2, attribute3) ), where attribute1, attribute2, attribute3 are all hashable. Of course, you provided no code and no error messages (the 'SoFarNoLuck' exception is not descriptive enough ; ) Hope this helps JKPeck wrote: I would like to be able use sets where the set members are objects of a class I wrote. I want the members to be distinguished by some of the object content, but I have not figured out how a set determines whether two (potential) elements are identical. I tried implementing __eq__ and __ne__ and __hash__ to make objects with identical content behave as identical for set membership, but so far no luck. I could subclass set if necessary, but I still don't know what I would need to override. TIA for any advice you can offer. -- http://mail.python.org/mailman/listinfo/python-list
