Re: Why do Pythoneers reinvent the wheel?
Stefano Masini wrote: SNIP I wonder how many people (including myself) have implemented their own versions of such modules, at least once in their pythonic life. I indeed have my own odict (even same name! :). My own pathutils (different name, but same stuff). My own validate... and so forth. As someone who implemented their own configuration mini-language with validation, blah, blah, blah (http://www.tundraware.com/Software/tconfpy/) I can give you a number of reasons - all valid for different people at different times: 1) The existing tool is inadequate for the task at hand and OO subclassing is overrated/overhyped to fix this problem. Even when you override base classes with your own stuff, you're still stuck with the larger *architecture* of the original design. You really can't subclass your way out of that, hence new tools to do old things spring into being. 2) It's a learning exercise. 3) You don't trust the quality of the code for existing modules. (Not that *I* have this problem :-p but some people might.) -- Tim Daneliuk [EMAIL PROTECTED] PGP Key: http://www.tundraware.com/PGP/ -- http://mail.python.org/mailman/listinfo/python-list
Re: Python compiled?
billiejoex [EMAIL PROTECTED] wrote: Hi all. I'm sorry for a noob question like this but I'll try to ask it anyway. One of the greatest problem that may discourage a new user to choose Python language is it's interpreted nature. I doubt it. C#, VB.NET, VBscript, Javascript and Perl have not suffered from being interpreted. -- - Tim Roberts, [EMAIL PROTECTED] Providenza Boekelheide, Inc. -- http://mail.python.org/mailman/listinfo/python-list
Re: nested tuples
Luis P. Mendes [EMAIL PROTECTED] wrote: I'm trying to solve this problem: suppose I'm reading a csv file and want to create a tuple of all those rows and values, like ((row1value1, row1value2, row1value3),(row2value1, row2value2, row2value3),..., (rowNvalue1, rowNvalue2, rowNvalue3)) I haven't found the way to do it just using tuples. How can I do it? Nevertheless, I can solve it like this: a=[] for row in reader: ~ elem = (row[0],row[1],row[2]) ~ a.append(elem) which will result in a list of tuples: [(row1value1, row1value2, row1value3),(row2value1, row2value2, row2value3),..., (rowNvalue1, rowNvalue2, rowNvalue3)] Then, I get what I want with tuple(a). Why? What is it about the list of tuples that you don't like? Philosophically, it's more in line with Guido's separation of list and tuple. -- - Tim Roberts, [EMAIL PROTECTED] Providenza Boekelheide, Inc. -- http://mail.python.org/mailman/listinfo/python-list
Re: Why do Pythoneers reinvent the wheel?
On 10 Sep 2005 02:10:59 EDT, Tim Daneliuk [EMAIL PROTECTED] wrote: As someone who implemented their own configuration mini-language with validation, blah, blah, blah (http://www.tundraware.com/Software/tconfpy/) Well, a configuration mini language with validation and blahs is not exactly what I would call _simple_... :) so maybe it doesn't even fit into my idea of testing-stdlib, or quick and dirty section of the manual (see my other post). But certainly it would be worth mentioning in the list of available solutions under the subsection Configuration files handling. 1) The existing tool is inadequate for the task at hand and OO subclassing is overrated/overhyped to fix this problem. Even when you override base classes with your own stuff, you're still stuck with the larger *architecture* of the original design. You really can't subclass your way out of that, hence new tools to do old things spring into being. That's true, but usually only when the original design if too simple comparing to the complexity of the problem. Instead a very general solution can usually be subclassed to easily handle a simpler problem. You still have to actually understand the general and complex design in order to be able to write subclasses, so maybe one can be tempted to punt on it, and write its own simple solution. But in this case it would just be enough to propose a few solutions in the testing-stdlib: a) one simple implementation for simple problems, easy to understand, but limited. b) one complex implementation for complex problems, c) one simplified implementation for simple problems, easy to understand, but subclassed from a complex model, that leaves room for more understanding and extension just in case one needs more power. I fully understand the difficulty of reusing code, as it always forces you to a learning curve and coming to compromises. But I've also wasted a lot of time reinventing the wheel and later found stuff I could have happily lived with if I only had known. 2) It's a learning exercise. Well, so we might as well learn a little more and rewrite os.path, the time module and pickle. Right? :) 3) You don't trust the quality of the code for existing modules. (Not that *I* have this problem :-p but some people might.) That's a good point, but it really boils down to being a wise programmer on one side, being able to discern the Good from the Bad, and an active community on the other side, able to provide good solutions and improve them. If either one is missing, then a lot of bad stuff can happen, and we can't really take community decisions basing on the assumption that programmers won't be able to understand, or that the community won't be able to provide. So we might as well assume that we have good programmers and an active community. Which I think is true, by the way! So, let's talk about a way to more effectively present available solutions to our good programmers! :) cheers, stefano -- http://mail.python.org/mailman/listinfo/python-list
Re: Python compiled?
Tim Roberts [EMAIL PROTECTED] writes: I doubt it. C#, VB.NET, VBscript, Javascript and Perl have not suffered from being interpreted. Are you kidding? -- http://mail.python.org/mailman/listinfo/python-list
Re: Why do Pythoneers reinvent the wheel?
Stefano Masini wrote: On 10 Sep 2005 02:10:59 EDT, Tim Daneliuk [EMAIL PROTECTED] wrote: As someone who implemented their own configuration mini-language with validation, blah, blah, blah (http://www.tundraware.com/Software/tconfpy/) Well, a configuration mini language with validation and blahs is not exactly what I would call _simple_... :) so maybe it doesn't even fit It's actually not *that* complicated. Then again, the code is not as elegant as is might be. 1) The existing tool is inadequate for the task at hand and OO subclassing is overrated/overhyped to fix this problem. Even when you override base classes with your own stuff, you're still stuck with the larger *architecture* of the original design. You really can't subclass your way out of that, hence new tools to do old things spring into being. That's true, but usually only when the original design if too simple comparing to the complexity of the problem. Instead a very general solution can usually be subclassed to easily handle a simpler problem. You still have to actually understand the general and complex design in order to be able to write subclasses, so maybe one can be tempted to punt on it, and write its own simple solution. But in this case it The problem is that for a lot of interesting problems, you don't know the generic big-picture stuff until you've hacked around at small specific examples. This is one of the deepest flaws in the gestalt of OO, IMHO. Good OO requires just what you suggest - and understanding of generics, specific applications, and just what to factor. But in the early going of new problems, you simply don't know enough. For the record, I think Python is magnificent both in allowing you to work quickly in the poking around stage of things, and then later to create the more elegant fully-featured architectures. One other point here: In the commericial world, especially, software tends to be a direct reflection of the organization's *processes*. Commercial institutions distinguish themselves from one another (in an attempt to create competitive advantage) by customizing and tuning these business processes - well, the successful companies do, anyway. For example, Wal-Mart is really a supply chain management company, not a consumer goods retailer. It is their supply chain expertise and IT systems that have knocked their competitors well into 2nd place. And here's the important point: These distinguishing business processes are unique and proprietary *by intent*. This means that generic software frameworks are unlikely to serve them well as written. I realize this is all at a level of complexity above what you had in mind, but it's easy to forget that a significant portion of the world likes/needs/benefits from things that are *not* particularly generic. This is thus reflected in the software they write. 2) It's a learning exercise. Well, so we might as well learn a little more and rewrite os.path, the time module and pickle. Right? :) I'm not deeply committed to that level of education at the moment :P 3) You don't trust the quality of the code for existing modules. (Not that *I* have this problem :-p but some people might.) So, let's talk about a way to more effectively present available solutions to our good programmers! :) Grappa? -- Tim Daneliuk [EMAIL PROTECTED] PGP Key: http://www.tundraware.com/PGP/ -- http://mail.python.org/mailman/listinfo/python-list
Re: Why do Pythoneers reinvent the wheel?
Tim Daneliuk wrote: 1) The existing tool is inadequate for the task at hand and OO subclassing is overrated/overhyped to fix this problem. Even when you override base classes with your own stuff, you're still stuck with the larger *architecture* of the original design. You really can't subclass your way out of that, hence new tools to do old things spring into being. Allthough I do think that you are completely wrong in principle there is some true point in your statement: refactoring a foreign ill designed tool that nevertheless provides some nice functionality but is not mentioned for being extendable by 3-rd party developers is often harder than writing a nice and even though inextendable tool on your own. That's independent of the language allthough I tend to think that C and Python programmers are more alike in their crude pragmatism than Java or Haskell programmers ( some might object that it is a bit unfair to equate Java and Haskell programmers, because no one ever claimed that the latter need code-generators and no intelligence to do their work ). Kay -- http://mail.python.org/mailman/listinfo/python-list
Re: Create new instance of Python class in C
phil hunt enlightened us with: Why do you need to maske lots of copies? The puzzles are stored in a NxN list of strings. The strings contain all the numerals that that block can contain. So a 9x9 puzzle contains 81 strings 123456789 when it's empty. My creation function picks a block that isn't a given, and fixes it to one of it's possible values. It then tries to solve the puzzle. If it works, it's done creating the puzzle. If it doesn't work, it starts over again in a recursive manner. The solver solves the puzzle in-place. That means that if I want to keep the original puzzle (the one that could be solved), I have to make a copy. And when you say lots of what numbers do you mean? 100? 100? That depends a lot. The parts picks a block that isn't a given and fixes it to one if it's possible values are both randomized. Sometimes it's 100, sometimes it's 5. The reason I ask is I recently wrote a program to solve Sudoku puzzles, and IIRC it didn't make copies at all. My solver doesn't create copies either. The creator does. I think I'll change my algorithm to just solve the puzzle and don't care about the original minimal puzzle that could be solved. I'll create a fully solved puzzle, and then use another routine to remove givens at random until the required number of givens is left. Of course, still maintaining solvability. That last part would require copying, but not as much as in the current situation. Sybren -- The problem with the world is stupidity. Not saying there should be a capital punishment for stupidity, but why don't we just take the safety labels off of everything and let the problem solve itself? Frank Zappa -- http://mail.python.org/mailman/listinfo/python-list
Re: Why do Pythoneers reinvent the wheel?
On 10 Sep 2005 03:16:02 EDT, Tim Daneliuk [EMAIL PROTECTED] wrote: frameworks are unlikely to serve them well as written. I realize this is all at a level of complexity above what you had in mind, but it's easy to forget that a significant portion of the world likes/needs/benefits from things that are *not* particularly generic. This is thus reflected in the software they write. In my opinion this has got more to deal with the open source vs. proprietary debate, that I wouldn't like to talk about, since it's somewhat marginal. What I was pointing out is well summarized in the subject: Why do Pythoneers reinvent the wheel? Reinventing the wheel (too much) is Bad for both the open source community and industry. It's bad for development in general. I got the feeling that in the specific case of Python the ultimate reason for this tendency in also the same reason why this language is so much better that others for, say, fast prototyping and exploration of new ideas: it's simple. So, without taking anything out of python, I'm wondering if a richer and less formal alternative standard library would help forming a common grounds where programmers could start from in order to build better and reinvent less. If such an aid to _general_ problem solving is indeed missing (I might be wrong) from the current state of python, I don't really think the reason is related to industry. I would look for reasons elsewhere, like it beeing difficult to come out with effective decisional support in an open source community, or something like this. I can certainly see the challenge of who and how should decide what goes in the library, and what not. stefano -- http://mail.python.org/mailman/listinfo/python-list
execute commands and return output
Hi all. I'm searching for a portable (working on *nix and win32) function
that executes a system command and encapsulate its output into a string.
Searching for the web I found this:
os.popen('command').read()
It is perfect but when che command return an error the funciotn returns an
empy string.
Does it is possible to return stdout and stderr too?
Best regards
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Re: List of integers L.I.S. (SPOILER)
Bryan Olson wrote: Could be. Yet you did write: It's incredibly fast! I just was obliged to exclaim It's incredibly fast! because I THOUGHT your first version handled ALL TEN testcases from the input. But the code read from the *20-lines* input *ONLY 2* its first lines. Usually they place heavy data testcase(s) at the end of the (whole) input. Like this: 3 2 3 1 7 4 5 6 1 2 7 3 ... ... ... 10 456 2 6789 ... ... ... ... ... 55444 1 ... 234 Surely producing an answer for list [2, 3, 1] will be incredibly fast for ANY language and for ANY algorithm. My first version bombed for the zero-length sequence. That was a mistake, sorry, but it may not be one of their test-cases. In my turn I can bet there's not an empty sequence testcase in the input. I wonder how many of the accepted entries would perform properly. Info of such kind they keep in secret (along with what the input data are). One more thing. They (the e-judge's admins) are not gods and they don't warrant that if they put 9 sec timelimit for a problem then this problem can be solved in all accepted languages (e.g. in Python). I never intended to submit this program for competition. Competition is not quite relevant word here. It just LOOKS as if it is a regular competetion. There nobody blames anybody. Moreover, judging on my own experience, there nobody is even interested in anybody. It's just a fun (but very useful fun). -- http://mail.python.org/mailman/listinfo/python-list
Re: nested tuples
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 | | Why? What is it about the list of tuples that you don't like? | Philosophically, it's more in line with Guido's separation of list and | tuple. I'm not saying that I don't like, I was just curious to know if there was a way to do it using exclusively tuples. Regards, Luis Mendes -BEGIN PGP SIGNATURE- Version: GnuPG v1.2.4 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFDIqgSHn4UHCY8rB8RAps/AJ905JXc5naxJYWLA0JLd0ZaJfQQWACeLXHJ pLE9nmMH+k81ybbB1Otj0hg= =2/LC -END PGP SIGNATURE- -- http://mail.python.org/mailman/listinfo/python-list
Re: Why do Pythoneers reinvent the wheel?
Kay Schluehr wrote: Tim Daneliuk wrote: 1) The existing tool is inadequate for the task at hand and OO subclassing is overrated/overhyped to fix this problem. Even when you override base classes with your own stuff, you're still stuck with the larger *architecture* of the original design. You really can't subclass your way out of that, hence new tools to do old things spring into being. Allthough I do think that you are completely wrong in principle there is some true point in your statement: refactoring a foreign ill designed tool that nevertheless provides some nice functionality but is not mentioned for being extendable by 3-rd party developers is often harder than writing a nice and even though inextendable tool on your own It has nothing to do with being ill designed, though that too would pose a (different) problem. It has to do with the fact that all realworld tools are a tradeoff between pragmatism and generic elegance. This tradeoff yields a tool/module/library/program with some POV about what problem it was solving. If the problem you wish to solve is not in that same space, you can inherit, subclass and do all the usual OO voodoo you like, you're not going to get clean results. On a more general note, for all the promises made over 3 decades about how OO was the answer to our problems, we have yet to see quantum improvements in code quality and productivity even though OO is now the thing everyone is supposed to subscribe to. In part, that's because it is profoundly difficult to see the most generic/factorable pieces of a problem until you've worked with it for a long time. Once you get past the a mammal is an animal level of problems, OO starts to self-destruct pretty quickly as the inheritance hierarchies get so complex no mere mortal can grasp them all. This is exactly Java's disease at the moment. It has become a large steaming pile of object inheritance which cannot be completely grokked by a single person. In effect, the traditional problem of finding algorithms of appropriate complexity gets transformed into a what should my inheritance hierarchy be problem. IMHO, one of Python's greatest virtues is its ability to shift paradigms in mid-program so that you can use the model that best fits your problem space. IOW, Python is an OO language that doesn't jam it down your throat, you can mix OO with imperative, functional, and list processing coding models simultaneously. In my view, the doctrinaire', indeed religious, adherence to OO purity has harmed our discipline considerably. Python was a nice breath of fresh air when I discovered it exactly because it does not have this slavish committment to an exclusively OO model. -- Tim Daneliuk [EMAIL PROTECTED] PGP Key: http://www.tundraware.com/PGP/ -- http://mail.python.org/mailman/listinfo/python-list
Re: Why do Pythoneers reinvent the wheel?
Stefano Masini wrote: On 10 Sep 2005 03:16:02 EDT, Tim Daneliuk [EMAIL PROTECTED] wrote: frameworks are unlikely to serve them well as written. I realize this is all at a level of complexity above what you had in mind, but it's easy to forget that a significant portion of the world likes/needs/benefits from things that are *not* particularly generic. This is thus reflected in the software they write. In my opinion this has got more to deal with the open source vs. proprietary debate, that I wouldn't like to talk about, since it's somewhat marginal. I think the point I was trying to make was there are times when a generic factoring of reusable code is unimportant since the code is so purpose-built that doing a refactoring makes no sense. What I was pointing out is well summarized in the subject: Why do Pythoneers reinvent the wheel? Reinventing the wheel (too much) is Bad for both the open source community and industry. It's bad for development in general. I got the I don't share your conviction on this point. Reinventing the wheel makes the wheel smoother, lighter, stronger, and rounder. Well, it *can* do this. Of far greater import (I think) is whether any particular implementation is fit to run across a breadth of platforms. To me, a signficant benefit of Python is that I am mostly able to program the same way across Unix, Windows, Mac and so on. SNIP If such an aid to _general_ problem solving is indeed missing (I might be wrong) from the current state of python, I don't really think the reason is related to industry. I would look for reasons elsewhere, like it beeing difficult to come out with effective decisional support in an open source community, or something like this. I can certainly see the challenge of who and how should decide what goes in the library, and what not. This is too abstract for me to grasp - but I admit to be old and feeble ;) I think what you see today in the standard library are two core ideas: 1) Modules that are more-or-less pass-through wrappers for the common APIs found in Unix and 2) Modules needed commonly to do the things that applications do like manipulate data structures or preserve active objects on backing store. If what you want here is for everyone to agree on a common set of these and stick exclusively to them, I think you will be sorely disappointed. OTOH, if someone has a better/faster/smarter reimplementation of what exists, I think you'd find the community open to embracing incremental improvement. But there is always going to be the case of what happened when I wrote 'tconfpy'. The existing configuration module was nice, but nowhere near the power of what I wanted, so I wrote something that suited me exactly (well ... sort of, 'tconfpy2' is in my head at the moment). If the community embraced it as a core part of their work, I'd be delighted (and surprised), but I don't need for that to happen in order for that module to have value to *me*, even though it does not displace the existing stuff. -- Tim Daneliuk [EMAIL PROTECTED] PGP Key: http://www.tundraware.com/PGP/ -- http://mail.python.org/mailman/listinfo/python-list
Re: execute commands and return output
billiejoex wrote:
Hi all. I'm searching for a portable (working on *nix and win32) function
that executes a system command and encapsulate its output into a string.
Searching for the web I found this:
os.popen('command').read()
It is perfect but when che command return an error the funciotn returns an
empy string.
Does it is possible to return stdout and stderr too?
Use subprocess:
from subprocess import Popen, PIPE
proc = Popen(['command', 'arg', 'arg'], stdout=PIPE, stderr=PIPE)
return_code = proc.wait()
if return_code == 0:
print Success:\n%s % proc.stdout.read()
else:
print Failure %s:\n%s % (return_code, proc.stderr.read())
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Re: execute commands and return output
billiejoex wrote:
Hi all. I'm searching for a portable (working on *nix and win32) function
that executes a system command and encapsulate its
output into a string.
Searching for the web I found this:
os.popen('command').read()
It is perfect but when che command return an error the funciotn returns an
empy string.
Does it is possible to return stdout and stderr too?
see the variations popen2, popen3 and popen4:
http://docs.python.org/lib/os-newstreams.html
or use the subprocess module:
http://docs.python.org/lib/module-subprocess.html
/F
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Re: execute commands and return output
Thank you for your help but I'm searching a different way.
Moreover it doesn't work always (for exaple: try a 'dir' command).
Because of I'm implementing a remote shell the
[[os.popen('command').read()]] rapresents the best for me because it can
also accepts arguments direclty (for example:
os.popen('netstat -a -n -o').read() and this is a great advantage.
I was looking at sys.stdout and sys.stderr. Can they be helpful?
Cheers
Use subprocess:
from subprocess import Popen, PIPE
proc = Popen(['command', 'arg', 'arg'], stdout=PIPE, stderr=PIPE)
return_code = proc.wait()
if return_code == 0:
print Success:\n%s % proc.stdout.read()
else:
print Failure %s:\n%s % (return_code, proc.stderr.read())
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Re: execute commands and return output
Hi ! Look (the doc for) Popen2, Popen3, Popen4 Subprocess @-salutations Michel Claveau -- http://mail.python.org/mailman/listinfo/python-list
Re: execute commands and return output
billiejoex wrote: Moreover it doesn't work always (for exaple: try a 'dir' command). why use os.system(dir) when Python already offers things like os.listdir, os.walk, and glob.glob ? /F -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Design Principles
[EMAIL PROTECTED] wrote: After all, the fact that Python is not strongly typed and is interpreted rather than compiled if you think those are facts, you don't understand how Python works. (hint: Python's both strongly typed *and* compiled) sacrificing programmer producitivity the ability to save a newline here and there doesn't affect the programmer productivity in any way whatsoever. /F -- http://mail.python.org/mailman/listinfo/python-list
Re: Why do Pythoneers reinvent the wheel?
On Sat, 10 Sep 2005 08:53:24 +0200, Stefano Masini [EMAIL PROTECTED] wrote: Well, so we might as well learn a little more and rewrite os.path, the time module and pickle. Right? :) And in fact people have done all of these: os.path: path.py (http://www.jorendorff.com/articles/python/path/) time: mxDateTime, the stdlib's datetime. pickle: XML serialization, YAML. So, let's talk about a way to more effectively present available solutions to our good programmers! :) PEP 206 (http://www.python.org/peps/pep-0206.html) suggests assembling an advanced library for particular problem domains (e.g. web programming, scientific programming), and then providing a script that pulls the relevant packages off PyPI. I'd like to hear suggestions of application domains and of the packages that should be included. --amk -- http://mail.python.org/mailman/listinfo/python-list
Re: execute commands and return output
billiejoex wrote:
Thank you for your help but I'm searching a different way.
Moreover it doesn't work always (for exaple: try a 'dir' command).
Because of I'm implementing a remote shell the
[[os.popen('command').read()]] rapresents the best for me because it can
also accepts arguments direclty (for example:
os.popen('netstat -a -n -o').read() and this is a great advantage.
If you really need shell evaluation, try subprocess.Popen('foo',
shell=True) instead.
--
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Re: global interpreter lock
Michael Sparks [EMAIL PROTECTED] writes: But I think to do it on Erlang's scale, Python needs user-level microthreads and not just OS threads. You've just described Kamaelia* BTW, except substitute micro-thread with generator :-) (Also we call the queues outboxes and inboxes, and the combination of a generator in a class with inboxes and outboxes components) * http://kamaelia.sf.net/ I don't see how generators substitute for microthreads. In your example from another post: class encoder(component): def __init__(self, **args): self.encoder = unbreakable_encryption.encoder(**args) def main(self): while 1: if self.dataReady(inbox): data = self.recv(inbox) encoded = self.encoder.encode(data) self.send(encoded, outbox) yield 1 You've got the main method creating a generator that has its own event loop that yields after each event it processes. Notice the kludge if self.dataReady(inbox): data = self.recv(inbox) instead of just saying something like: data = self.get_an_event(inbox) where .get_an_event blocks (i.e. yields) if no event is pending. The reason for that is that Python generators aren't really coroutines and you can't yield except from the top level function in the generator. In that particular example, the yield is only at the end, so the generator isn't doing anything that an ordinary function closure couldn't: def main(self): def run_event(): if self.dataReady(inbox): data = self.recv(inbox) encoded = self.encoder.encode(data) self.send(encoded, outbox) return run_event Now instead of calling .next on a generator every time you want to let your microthread run, just call the run_event function that main has returned. However, I suppose there's times when you'd want to read an event, do something with it, yield, read another event, and do something different with it, before looping. In that case you can use yields in different parts of that state machine. But it's not that big a deal; you could just use multiple functions otherwise. All in all, maybe I'm missing something but I don't see generators as being that much help here. With first-class continuations like Stackless used to have, the story would be different, of course. -- http://mail.python.org/mailman/listinfo/python-list
Re: Using Python with COM to communicate with proprietary Windows software
On Fri, 09 Sep 2005 08:36:00 +0200, Thomas Heller [EMAIL PROTECTED]
wrote:
{...}
(I have released and announced this 3 weeks ago, but haven't got a
single feedback. So it seems the need to access custom interfaces is
very low.)
I have downloaded it and am trying to find the time to play with it
(unsuccessfully so far).
As someone working with a large, complex, COM library with minimal
IDispatch support, I'm really looking forward to this.
However, at the moment I'm limited to Python 2.2 and ctypes 0.6.3 (which
is allowing me to get the job done!!).
Regardless, I thank you for what you have released!
Cheers,
Andrew.
-
Andrew I MacIntyre These thoughts are mine alone...
E-mail: [EMAIL PROTECTED] (pref) | Snail: PO Box 370
[EMAIL PROTECTED] (alt) |Belconnen ACT 2616
Web:http://www.andymac.org/ |Australia
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Re: execute commands and return output
billiejoex wrote:
Hi all. I'm searching for a portable (working on *nix and win32) function
that executes a system command and encapsulate its output into a string.
Searching for the web I found this:
os.popen('command').read()
It is perfect but when che command return an error the funciotn returns an
empy string.
Does it is possible to return stdout and stderr too?
You may want to look at the subprocess [1] module and its Popen class [2].
[1] http://python.org/doc/2.4.1/lib/module-subprocess.html
[2] http://python.org/doc/2.4.1/lib/node234.html
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Re: Why do Pythoneers reinvent the wheel?
Michael Amrhein wrote: Stefano Masini schrieb: On 8 Sep 2005 08:24:50 -0700, Fuzzyman [EMAIL PROTECTED] wrote: What is pythonutils ? = ConfigObj - simple config file handling validate - validation and type conversion system listquote - string to list conversion StandOut - simple logging and output control object pathutils - for working with paths and files cgiutils - cgi helpers urlpath - functions for handling URLs odict - Ordered Dictionary Class Fuzzyman, your post reminded me of something I can't stop thinking about. Please don't take this as a critique on your work. I place myself on the same side of yours. I just wanted to share this thought with everybody had an opinion about it. I wonder how many people (including myself) have implemented their own versions of such modules, at least once in their pythonic life. I indeed have my own odict (even same name! :). My own pathutils (different name, but same stuff). My own validate... and so forth. This is just too bad. There are a few ares where everybody seems to be implementing their own stuff over and over: logging, file handling, ordered dictionaries, data serialization, and maybe a few more. I don't know what's the ultimate problem, but I think there are 3 main reasons: 1) poor communication inside the community (mhm... arguable) 2) lack of a rich standard library (I heard this more than once) 3) python is such an easy language that the I'll do it myself evil side lying hidden inside each one of us comes up a little too often, and prevents from spending more time on research of what's available. [snip..] Did you take a look at pyPI (http://www.python.org/pypi) ? At least you'd find another odict ... Oh right. Where ? I remember when I started coding in Python (about two years ago) in one of my first projects I ended up re-implementing some stuff that is in the standard library. The standard library is *fairly* big - but the 'Python blessed' modules idea sounds good. I've often had the problem of having to assess multiple third party libraries/frameworks and decide which of several alternatives is going to be best for me - without really having the information on which to base a decision (and nor the time to try them all out). Web templating and web application frameworks are particularly difficult in this area. If a module is in the standard library then *most* developers will *first* use that - and only if it's not suitable look for something else. All the best, Fuzzyman http://www.voidspace.org.uk/python ;-) Michael -- http://mail.python.org/mailman/listinfo/python-list
Re: Why do Pythoneers reinvent the wheel?
Stefano Masini wrote: cut reinventing wheel example Although I'm not experienced enough to comment on python stuff itself I do know that in general there are 2 reasons that people reinvent the wheel: - They didn't know of the existence of the first wheel - They have different roads Those reasons can even be combined. The more difficult it is to create a new wheel the bigger the chance is that you: - Search longer for fitting technologies - Adapt your road -- mph -- http://mail.python.org/mailman/listinfo/python-list
Re: Why do Pythoneers reinvent the wheel?
A.M. Kuchling wrote: PEP 206 (http://www.python.org/peps/pep-0206.html) suggests assembling an advanced library for particular problem domains (e.g. web programming, scientific programming), and then providing a script that pulls the relevant packages off PyPI. I'd like to hear suggestions of application domains and of the packages that should be included. I'm not against pointing people in what I consider to be the right direction, but PEP 206 seems to be quite the lobbying instrument for people to fast-track pet projects into the standard library (or some super-distribution), perhaps repeating some of the mistakes cited in that document with regard to suitability. Meanwhile, in several areas, some of the pressing needs of the standard library would remain unaddressed if left to some kind of Pythonic popularity contest; for example, everyone likes to dish out their favourite soundbites and insults about DOM-based XML APIs, but just leaving minidom in the library in slow motion maintenance mode whilst advocating more Pythonic APIs doesn't help Python's interoperability with (or relevance to) the wider development community. The standard library is all about providing acceptable solutions so that other people aren't inclined or forced to write their own. Every developer should look at their repertoire of packages and consider which ones wouldn't need to exist if the standard library had been better. For me, if there had been a decent collection of Web application objects in the standard library, I wouldn't have created WebStack; if I didn't have to insist on PyXML and then provide patches for it in order to let others run software I created, I wouldn't have created libxml2dom. PEP 206 is an interesting idea but dangerous because as a PEP it promotes a seemingly purely informational guide to some kind of edict, and (speaking from experience) since a comprehensive topic guide to any reasonable number of packages and solutions is probably too much work that no-one really wants to do anyway, the likelihood of subjective popularity criteria influencing the selection of presented software means that the result may be considerably flawed. Although I see that a common trend these days is to form some kind of narrow consensus, hype it repeatedly and, in the name of one cause, to push another agenda entirely, all whilst ignoring the original problems that got people thinking in the first place, I am quite sure that as a respected Python contributor this was not a goal of yours in writing the PEP. However, we should all be aware of the risks of picking favourites, even if the level of dispute around those favourites is likely to be much lower for some packages than for others. This overly harsh criticism really brings me to ask: what happened to the maintenance and promotion of the python.org topic guides? Or do people only read PEPs these days? Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: The penis is way too delicate for masturbation
Chucky Janica wrote: Once upon a time - for example, 1 Sep 2005 05:32:54 -0700 - there was this guy, or something, called [EMAIL PROTECTED], and they made us all feel better by saying the following stuff: . That penis, more to the point, is too small for masturbation. CJ Actually, I thought it was an advertisment for docking irons, you know, the same as they use for docking sheeps' tails ... I'll bet this spammer's got Castration Envy. -- Good, late in to more rewarding well. Well, you tonight. And I was lookintelligent woman of Ming home. I trust you with a tender silence. I get a word into my hands, a different and unbelike, probably - 'she fortunate fat woman', wrong word. I think to me, I justupid. Let not emacs meta-X dissociate-press write your romantic dialogs...!!! -- http://mail.python.org/mailman/listinfo/python-list
Re: simple problem with os.rename() parameters - path with spaces
Peter Hansen wrote: Tom wrote: I'm having a problem using a path with spaces as a parameter to os.rename() in a program on WinXP. This works fine at the command line (where the folder c:\aa bb exists) os.rename( c\aa bb, c:\cc dd ); But, I can't get it to work in my program, eg. print SrcDir print NewDir os.rename( SrcDir, NewDir ); when I run this I get something like this: e:\\music\\Joni Mitchell\\ogg-8 e:\\music.ogg\\Joni Mitchell\\ogg-8 What kind of device is drive E: ? Are you certain it allows spaces in filenames? Can you do the same renaming *using the same drive* at the command line or from Explorer? -Peter Drive E: is removable, so I was careful to verify that that was a factor in the problem. Yes, I can do the same renaming, with the same drive, at the command line. I think I put the emphasis in the wrong place in my question. This isn't really about os.rename(). It is about putting a filename with spaces into a string object and then using it as a parameter to an 'os' command. Tom. -- http://mail.python.org/mailman/listinfo/python-list
Re: simple problem with os.rename() parameters - path with spaces
Yes, I am sure about those things. I've tried shutil.move and got the same result. Forward slash? I'll give that a try and report back here if it works. Thanks, Tom. Larry Bates wrote: Are you sure the source directory exists and you have rights to rename it? Because the rename works for me. But you may want to look at shutil.move and/or use forward slashes (they work under Windows) -Larry Bates Tom wrote: I'm having a problem using a path with spaces as a parameter to os.rename() in a program on WinXP. This works fine at the command line (where the folder c:\aa bb exists) os.rename( c\aa bb, c:\cc dd ); But, I can't get it to work in my program, eg. print SrcDir print NewDir os.rename( SrcDir, NewDir ); when I run this I get something like this: e:\\music\\Joni Mitchell\\ogg-8 e:\\music.ogg\\Joni Mitchell\\ogg-8 Traceback (most recent call last): File E:\Music\MoveMusic.py, line 64, in ? main(); ... File E:\Music\MoveMusic.py, line 49, in Visit os.mkdir( NewDir ); OSError: [Errno 22] Invalid argument: 'e:\\music.ogg\\Joni Mitchell\\ogg-8' I've tried different combinations of single backslash vs. double backslash, and quoted vs. non-quoted, but it always fails. The problem is not specific to os.rename. If I instead use mkdir( SrcDir ) I get the same problem. Thanks, Tom. -- http://mail.python.org/mailman/listinfo/python-list
How to handle very large MIME Messages with the email package?
Looking at the email package, it seems all the MIMExxx classes takes string but not file object as the payload. I need to handle very large MIME messages say up to 100M. And possibly many of them. Is email package sufficient. If not is it possible to extend it? Looking at a previous thread it seems the standard library is not sufficient. http://groups.google.com/group/comp.lang.python/browse_frm/thread/7d1754c1ead54f33/5b6bd38a049e7f6c?q=mime+email+file+objectrnum=5hl=en#5b6bd38a049e7f6c -- http://mail.python.org/mailman/listinfo/python-list
Re: nested tuples
Luis P. Mendes [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] | Why? What is it about the list of tuples that you don't like? | Philosophically, it's more in line with Guido's separation of list and | tuple. I'm not saying that I don't like, I was just curious to know if there was a way to do it using exclusively tuples. A list of lists can be built top down. A tuple of tuples must be built bottom up, and each tuple must be built with one call to tuple(). But tuple(it) will take any iterable, so write, say, a generator that yields lower-level tuples. Terry J. Reedy -- http://mail.python.org/mailman/listinfo/python-list
Re: Python compiled?
Tim Roberts [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] billiejoex [EMAIL PROTECTED] wrote: Hi all. I'm sorry for a noob question like this but I'll try to ask it anyway. One of the greatest problem that may discourage a new user to choose Python language is it's interpreted nature. I doubt it. C#, VB.NET, VBscript, Javascript and Perl have not suffered from being interpreted. Nor has 386 'machine language' suffered from being interpreted, at a deeper level, by microcode. tjr -- http://mail.python.org/mailman/listinfo/python-list
Re: What's the difference between VAR and _VAR_?
On 8 Sep 2005 22:48:05 -0700 Johnny Lee [EMAIL PROTECTED] wrote: I thought there must be something special when you named a VAR with '_' the first character. Maybe it's just a programming style and I had thought too much... It is just a programming style issue. In Python, variables and functions beginning with '_' are regarded by convention to be semi-private; essentially the Python equivalent of 'protected'. Since Python has no formal access specifications, conventions like this have been adopted. Likewise, '__' is private. Code using your code can bypass this, of course, but it's just a signal to the programmer 'avoid using this; it is an internal detail that may change.' Incidentally, epydoc regards all items beginning with '_' as private, and hides them from the public documentation it generates. And, in one project I'm working on, I use underscores to base/background/helper modules in a mechanism where modules are dynamically loaded (to prevent name collisions, since no dynamically loaded module will begin with an underscore). - Michael -- http://mail.python.org/mailman/listinfo/python-list
Re: OpenSource documentation problems
On Fri, 09 Sep 2005 18:16:36 -0400 Mike Meyer [EMAIL PROTECTED] wrote: You need a better browser. Mine - at least on Unix - have an option to dump textareas into text files, invoke my favorite editor on them, and then read the file back in when the editor exits. Assuming i'm not running the browser in that editor in the first place. Which browser might this be? I am curious. - Michael -- http://mail.python.org/mailman/listinfo/python-list
Re: simple problem with os.rename() parameters - path with spaces
Tom wrote:
Drive E: is removable, so I was careful to verify that that was a factor
in the problem.
Yes, I can do the same renaming, with the same drive, at the command line.
I think I put the emphasis in the wrong place in my question. This
isn't really about os.rename(). It is about putting a filename with
spaces into a string object and then using it as a parameter to an 'os'
command.
That can't really be all there is to the issue, since other people can
successfully use spaces in filenames passed to 'os' commands including
os.rename. There must be something special with _your_ situation. What
else could it be except the file system?
Oh... wait, I see now. Look closely at your error message:
Traceback (most recent call last):
File E:\Music\MoveMusic.py, line 64, in ?
main();
...
File E:\Music\MoveMusic.py, line 49, in Visit
os.mkdir( NewDir );
OSError: [Errno 22] Invalid argument: 'e:\\music.ogg\\Joni
Mitchell\\ogg-8'
Where do you think those double quotation marks came from? What happens
if you try the following instead of using the variables you were trying
to use?
os.rename(e:\\music\\Joni Mitchell\\ogg-8,
e:\\music.ogg\\Joni Mitchell\\ogg-8)
Now try it with this and observe how you get (I predict) the same error
message as you originally got, and note what your mistake was:
os.rename('e:\\music\\Joni Mitchell\\ogg-8',
'e:\\music.ogg\\Joni Mitchell\\ogg-8')
(To avoid confusion, cut and paste the above lines rather than
attempting to retype them.)
-Peter
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Re: Why do Pythoneers reinvent the wheel?
Stefano Masini [EMAIL PROTECTED] writes: It would be great if there was a section in the Python manual like this: Quick and Dirty: Commonly needed tricks for real applications 1. odict 2. file system management 3. xml (de)serialization 4. ... Each section would describe the problem and list one or a few recommended implementations. All available under __testing_stdlib__. Appoint somebody as the BDFL and make the process of updating the testing stdlib democratic enough to allow for more evolution freedom than the stable stdlib. Why are you reinvinting the wheel? Things that are very similar to this already exist. There are a number of code repositories/listings around - PyPI being the obvious example, because it's linked to from python.org. The Python cookbook site is closer to what you're talking about, though. And the latter reveals the problem with your suggestion - this section would pretty much outweigh the rest of the documentation. Clearly, it should be a separate book - but we've already got that. However, a list of these isn't in the manual. The only thing I could find was a page on the Wiki about How to publish a module. That doesn't seem likely to be found by someone trying to find code. I think the manual does need a section on how to find code other than the library. But where do you put it? mike -- Mike Meyer [EMAIL PROTECTED] http://www.mired.org/home/mwm/ Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information. -- http://mail.python.org/mailman/listinfo/python-list
Re: Why do Pythoneers reinvent the wheel?
In article [EMAIL PROTECTED], Tim Daneliuk [EMAIL PROTECTED] wrote: IMHO, one of Python's greatest virtues is its ability to shift paradigms in mid-program so that you can use the model that best fits your problem space. IOW, Python is an OO language that doesn't jam it down your throat, you can mix OO with imperative, functional, and list processing coding models simultaneously. In my view, the doctrinaire', indeed religious, adherence to OO purity has harmed our discipline considerably. Python was a nice breath of fresh air when I discovered it exactly because it does not have this slavish committment to an exclusively OO model. +1 QOTW -- Aahz ([EMAIL PROTECTED]) * http://www.pythoncraft.com/ The way to build large Python applications is to componentize and loosely-couple the hell out of everything. -- http://mail.python.org/mailman/listinfo/python-list
Re: Why do Pythoneers reinvent the wheel?
In article [EMAIL PROTECTED], Dave Brueck [EMAIL PROTECTED] wrote: Many projects (Python-related or not) often seem to lack precisely what has helped Python itself evolve so well - a single person with decision power who is also trusted enough to make good decisions, such that when disagreements arise they don't typically end in the project being forked (the number of times people disagreed but continued to contribute to Python is far higher than the number of times they left to form Prothon, Ruby, and so on). In the end, domain-specific BDFLs and their projects just might have to buble to the top on their own, so maybe the best thing to do is find the project you think is the best and then begin contributing and promoting it. You've got a point there -- reStructuredText seems to be succeeding precisely in part because David Goodger is the BDFNow. -- Aahz ([EMAIL PROTECTED]) * http://www.pythoncraft.com/ The way to build large Python applications is to componentize and loosely-couple the hell out of everything. -- http://mail.python.org/mailman/listinfo/python-list
Re: execute commands and return output
Thanks for suggestions. I'll try one of these solutions soon. -- http://mail.python.org/mailman/listinfo/python-list
Unusual Python Sighting
In article: http://humorix.org/articles/2005/08/notice/ ... 6. The use of semantically significant whitespace in Python® programs might be protected by intellectual property laws in five (5) countries, --Scott David Daniels [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: OpenSource documentation problems
In article [EMAIL PROTECTED], Michael Ekstrand [EMAIL PROTECTED] wrote: On Fri, 09 Sep 2005 18:16:36 -0400 Mike Meyer [EMAIL PROTECTED] wrote: You need a better browser. Mine - at least on Unix - have an option to dump textareas into text files, invoke my favorite editor on them, and then read the file back in when the editor exits. Assuming i'm not running the browser in that editor in the first place. Which browser might this be? I am curious. Lynx -- Aahz ([EMAIL PROTECTED]) * http://www.pythoncraft.com/ The way to build large Python applications is to componentize and loosely-couple the hell out of everything. -- http://mail.python.org/mailman/listinfo/python-list
IDisatch and pythoncom
Hi,
I have a COM component server that just exposes the IDispatch interface
but when you use it in a VB app you can access other method. I think the
way to access the other methods( as does it VBA for ex) is to use
Invoke but don't know how to do it in python.
Say for ex i want to convert this very simple example with only
IDispatch interface .
import win32com.client
o = win32com.client.Dispactch('Excel.Application')
o.WorkBooks.Add()
Thx for your help
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Re: Python versus Perl
* Dieter Vanderelst (2005-09-06 18:03 +0100) I'm currently comparing Python versus Perl to use in a project that involved a lot of text processing. I'm trying to determine what the most efficient language would be for our purposes. I have to admit that, although I'm very familiar with Python, I'm complete Perl noob (and I hope to stay one) which is reflected in my questions. I know that the web offers a lot of resources on Python/Perl differences. But I couldn't find a satisfying answer to my questions: 1 - How does the speed of execution of Perl compares to that of Python? Of course Python is faster than Perl. It's the same reason why Mercedes are faster than BMWs (or was it the other way round?). 2 - Regular Expressions are a valuable tool in text processing. I have noticed that Regular Expressions are executed very fast in Python. Does anybody know whether Python executes RE faster than Perl does? Again: this question doesn't make sense. It's up to you to write your Regular Expressions fast. 3 - In my opinion Python is very well suited for text processing. Does Perl have any advantages over Python in the field of textprocessing (like a larger standard library maybe). I hope somebody can answer my questions. Of course, every remark and tip on Python/Perl in texprocessing is most welcome. http://gnosis.cx/TPiP/ In case regular expression operations prove to be a genuinely problematic performance bottleneck in an application, there are four steps you should take in speeding things up. Try these in order: 1. Think about whether there is a way to simplify the regular expressions involved. Most especially, is it possible to reduce the likelihood of backtracking during pattern matching? You should always test your beliefs about such simplification, however; performance characteristics rarely turn out exactly as you expect. 2. Consider whether regular expressions are -really- needed for the problem at hand. With surprising frequency, faster and simpler operations in the [string] module (or, occasionally, in other modules) do what needs to be done. Actually, this step can often come earlier than the first one. 3. Write the search or transformation in a faster and lower-level engine, especially [mx.TextTools]. Low-level modules will inevitably involve more work and considerably more intense thinking about the problem. But order-of-magnitude speed gains are often possible for the work. 4. Code the application (or the relevant parts of it) in a different programming language. If speed is the absolutely first consideration in an application, Assembly, C, or C++ are going to win. Tools like swig--while outside the scope of this book--can help you create custom extension modules to perform bottleneck operations. There is a chance also that if the problem -really must- be solved with regular expressions that Perl's engine will be faster (but not always, by any means). -- http://mail.python.org/mailman/listinfo/python-list
Re: OpenSource documentation problems
Michael Ekstrand [EMAIL PROTECTED] writes: On Fri, 09 Sep 2005 18:16:36 -0400 Mike Meyer [EMAIL PROTECTED] wrote: You need a better browser. Mine - at least on Unix - have an option to dump textareas into text files, invoke my favorite editor on them, and then read the file back in when the editor exits. Assuming i'm not running the browser in that editor in the first place. Which browser might this be? I am curious. w3m has this feature. emacs-w3m uses w3m as a back end, rendering into an emacs buffer, and gets this by default. And as I noted in the message you quoted, there's an extension available for FireFox that gives you the ability to invoke an external editor on the text in a textarea. The first browser I ever saw that did this was iBrowse. It attached a button to each text area that invoked an external editor on the contents of the textarea. iBrowse is my all time favorite browser. The list of desirable features was simply amazing, and I've never seen it's equal. The mozilla family comes close if you consider all the extensions, but iBrowse had them built in - and still rendered faster than a text only browser on the same platform. I doubt if I'll ever see it's like again. mike -- Mike Meyer [EMAIL PROTECTED] http://www.mired.org/home/mwm/ Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information. -- http://mail.python.org/mailman/listinfo/python-list
pydoc search in browser
Hi I am a newbie to pydoc and I need some help. I would really appreciate if some one can tell me how to add search box in a page generated by pydoc, e.g. I want to add serch like the one in pydoc.org thanks sakcee -- http://mail.python.org/mailman/listinfo/python-list
Re: Using Python with COM to communicate with proprietary Windows software
On Fri, 09 Sep 2005 08:36:00 +0200, Thomas Heller [EMAIL PROTECTED] wrote: Sounds like a perfect job for comtypes, which is a COM library implemented in pure Python, based on ctypes. comtypes should make it easy to access custom (non-dispatch derived) com interfaces, or the vtable based part of dual interfaces - it would be good however, if you have a type library for the interfaces. http://sourceforge.net/projects/comtypes/ No docs yet, but there are tests included which should get you started. (I have released and announced this 3 weeks ago, but haven't got a single feedback. So it seems the need to access custom interfaces is very low.) Thommas After some testing today, it does seem to do exactly what I wanted -- I can now access the custom but IDispatch-like COM interface that I couldn't access with win32com (or with Java + jawin). It might be possible in other ways, but using comtypes was definitely the most painfree way (everything, including the return values from the methods, worked as expected). Thank you very much. Of course, this does not complete my task -- although I can now use my interface to send messages and commands to the big log tool, I still need to implement a COM server and pass a pointer to its interface through one of the messages to the com server to be able to receive data: BridgeInterface.StartLogging(filename) --- works fine, didn't work before BridgeInterface.Advise(ptr) --- Now, I need to create a new interface for receiving the data sent from the log application, so that I can (at first) print it This _shouldn't_ be too difficult -- I know which methods must be implemented (basically just some kind of event handling to deal with randomly arriving log points, should be implemented as onMsg() on my COM server side, and some other similar methods), but I don't really know how. I have tried doing simple COM servers using win32com, but is it equally possible to implement such a simple thing in comtypes? I didn't find any server side examples in comtypes, but perhaps there is a way? -- Joakim Persson M.Sc student, CS/E @ LTH -- http://mail.python.org/mailman/listinfo/python-list
Re: IDisatch and pythoncom
Hi ! Perhaps : .Dispactch vs .Dispatch ? @-salutations Michel Claveau -- http://mail.python.org/mailman/listinfo/python-list
Re: Unusual Python Sighting
Scott David Daniels wrote: In article: http://humorix.org/articles/2005/08/notice/ ... 6. The use of semantically significant whitespace in Python® programs might be protected by intellectual property laws in five (5) countries, --Scott David Daniels [EMAIL PROTECTED] It appears you indented the quotation. I'm going to have to report you. -- http://mail.python.org/mailman/listinfo/python-list
Re: encryption with python
Steven D'Aprano [EMAIL PROTECTED] writes: On Wed, 07 Sep 2005 14:31:03 -0700, jlocc wrote: Basically I will like to combine a social security number (9 digits) and a birth date (8 digits, could be padded to be 9) and obtain a new 'student number'. It would be better if the original numbers can't be traced back, they will be kept in a database anyways. Hope this is a bit more specific, thanks!!! There are one-way encryption functions where the result can't easily be traced back to the input, but why do you need the input anyway? Well, there is a form of security design that involves one-way encryption of confidential information. You might want to be able to search on SSN, but not have the actual SSN stored in the database. So, you are prepared to deal with the inevetable, I lost my password/student ID, can you still look up my records? Don't think it applies in this case, but might in some other cases. -- Steven. -- Kirk Job-Sluder The square-jawed homunculi of Tommy Hilfinger ads make every day an existential holocaust. --Scary Go Round -- http://mail.python.org/mailman/listinfo/python-list
Re: Python versus Perl
Dieter Vanderelst [EMAIL PROTECTED] wrote: 1 - How does the speed of execution of Perl compares to that of Python? To a first-order approximation, Perl and Python run at the same speed. They are both interpreted languages with roughly the same kind of control flow and data structures. The two have wildly different kinds of syntax, but the underlying machinery is fairly similar. Don't make a decision on which to use based on execution speed. If you feel compelled to ignore this advice, then don't make the decision until you've coded your application in both languages and done careful benchmarking with realistic data for your application domain. I have noticed that Regular Expressions are executed very fast in Python. Does anybody know whether Python executes RE faster than Perl does? Same answer as above -- for a first cut, assume they are the same speed. If you insist on a better answer, do measurements on real data. The big advantage the Python has over Perl is speed of development and ease of maintenance (i.e. a year from now, you can still understand what your own code does). -- http://mail.python.org/mailman/listinfo/python-list
Re: Why do Pythoneers reinvent the wheel?
On Sat, 10 Sep 2005 16:55:51 +0200, Martin P. Hellwig [EMAIL PROTECTED] wrote: Stefano Masini wrote: cut reinventing wheel example Although I'm not experienced enough to comment on python stuff itself I do know that in general there are 2 reasons that people reinvent the wheel: - They didn't know of the existence of the first wheel - They have different roads - They want the feeling that they are in the same league as the original inventor ;-) Those reasons can even be combined. The more difficult it is to create a new wheel the bigger the chance is that you: - Search longer for fitting technologies - Adapt your road - Think more carefully about ego satisfaction cost/benefit vs getting the job done ;-) Regards, Bengt Richter -- http://mail.python.org/mailman/listinfo/python-list
Re: Python compiled?
Terry Reedy wrote: Tim Roberts [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] billiejoex [EMAIL PROTECTED] wrote: Hi all. I'm sorry for a noob question like this but I'll try to ask it anyway. One of the greatest problem that may discourage a new user to choose Python language is it's interpreted nature. I doubt it. C#, VB.NET, VBscript, Javascript and Perl have not suffered from being interpreted. Nor has 386 'machine language' suffered from being interpreted, at a deeper level, by microcode. I think both you and Paul may be missing Tim's point. I don't think he's talking about suffering in technical respects, like speed. He's talking about popularity. -- Robert Kern [EMAIL PROTECTED] In the fields of hell where the grass grows high Are the graves of dreams allowed to die. -- Richard Harter -- http://mail.python.org/mailman/listinfo/python-list
Find roots of ill-conditioned polynomials
If you are using the root finder in Numeric, and are having problems, check out the root finder in the ratfun module. My testing indicates that it will give the exact roots of a Wilkinson polynomial of degree 100. For more information see http://calcrpnpy.sourceforge.net/ratfun.html -- http://mail.python.org/mailman/listinfo/python-list
Re: encryption with python
Paul Rubin http://[EMAIL PROTECTED] writes: Kirk Job Sluder [EMAIL PROTECTED] writes: Well, there is a form of security design that involves one-way encryption of confidential information. You might want to be able to search on SSN, but not have the actual SSN stored in the database. So, you are prepared to deal with the inevetable, I lost my password/student ID, can you still look up my records? The minute you provide a way to do that without secret keys, you have a security hole. Providing any kind of access to data involves creating a security hole. This is the biggest flaw in most discussions of computer security. Too much of it depends on everyone remembering (and using) unique cryptographically strong keys. You have a client on the phone who needs access to information, but has forgotten or lost the 10-digit unique ID and the PIN you gave them two years ago. How do you provide that client with the information he or she needs? This is the kind of dilemma that one-way encryption is designed to make a tiny bit safer. SSNs + some other secret (such as mother's maiden name) is certainly crappy security. However, I don't think we are going to see widespread adoption of anything better in the near future. But even if we go with more secure authentication tokens, there is usually no reason to store the authentication token in plaintext. SSN's are 9 digits which means there are 1 billion of them. If there are 100,000 hashed SSN's in the database, the attacker (since this is clpy) can read them all into a Python dict. S/he then starts generating SSN's at random and hashing them and checking whether those hashes appear in the dict. Doing stuff like iterated hashes to slow the attacker down doesn't help that much: the attacker needs to hash only 10,000 or so SSN's to be likely to hit one that's in the dict. If the attacker can hash all 10**9 SSN's, which isn't all that terribly many, every SSN in the database spills. Of course, an additional step I didn't mention was that in actual practice the SSNs would be hashed with a strong random secret key. But from my point of view, the possibility for dictionary attacks is pretty much unavoidable as long as we are dealing just with memorized tokens. We've been bitching, whining and moaning about the small keyspace and poor quality of what users are willing to memorize for 20 years. We can complain about it for the next 10 which is about how long it will take for any kind of alternative to be adopted. I still think that one-way hashing of authentication secrets is better than plain-text storage. Bottom line: to keep confidential stuff secure, you need actual security. The only way to keep confidential stuff secure is to shred it, burn it, and grind the ashes. I think the fundamental problem is that that most customers don't want actual security. They want to be able to get their information by calling a phone number and saying a few words/phrases they memorized in childhood. Given the current market, it seems to be cheaper to deal with breaks after the fact than to expect more from customers. -- Kirk Job-Sluder The square-jawed homunculi of Tommy Hilfinger ads make every day an existential holocaust. --Scary Go Round -- http://mail.python.org/mailman/listinfo/python-list
calling command line programs?
Hi all, This is probably a very newbie question, but after searching google and docs @ python.org I can't find an answer, so maybe someone would be able to help? I'd like to call command-line functions from my python script (like you would in perl using backticks)... Is there a way of doing this? And if so, how does the environment get treated (I have some variables in my env that the programs I'd be calling need to see). Thanks much! Eugene -- http://mail.python.org/mailman/listinfo/python-list
class 'Exception', unable to use 'super' to call superclass initializer
Hi, environment: Python 2.4, GNU/Linux, kernel 2.6.12.2 having subclassed 'Exception' I'm trying to call the initialiser __init__(...) of the superclass Exception with 'super(..).__init__(..)' . However, trying to do so results in a 'TypeError: super() argument 1 must be type, not classobj'. Now, if I use 'Exception.__init__(..)' instad of super(..)... ,everything works just as one would expect. Why does 'super(..).__init__(..)' fail? thank you for any suggestions chriss Here is some example code to illustrate the point: class WorkingException(Exception): def __init__(self, message): # works as I would expect Exception.__init__(self, message) class BrokenException(Exception): def __init__(self, message): # fails with a typeError super(BrokenException, self).__init__(self, message) # - case 1 - try: raise WorkingException(Hello WorkingException) except WorkingException, e: print e # - case 3 - try: raise BrokenException(Hello BrokenException) except BrokenException, e: print e -- http://mail.python.org/mailman/listinfo/python-list
Re: encryption with python
Kirk Job Sluder [EMAIL PROTECTED] writes: You have a client on the phone who needs access to information, but has forgotten or lost the 10-digit unique ID and the PIN you gave them two years ago. How do you provide that client with the information he or she needs? This is the kind of dilemma that one-way encryption is designed to make a tiny bit safer. You need secret keys then, and you need to secure them. If you have a secure secret key K, you can store something like HMAC(K, SSN) and that is pretty safe from offline attacks. Of course, an additional step I didn't mention was that in actual practice the SSNs would be hashed with a strong random secret key. But now you have to maintain that secret key and its secrecy, which is not a trivial task. It's not an unsolveable problem but you can't handwave it. We're told there is already a secure database in the picture somewhere, or at least one that unescapeably contains cleartext SSN's, so that's the system that should assign the ID numbers and handle SSN-based queries. I think the fundamental problem is that that most customers don't want actual security. They want to be able to get their information by calling a phone number and saying a few words/phrases they memorized in childhood. A voice exemplar stored at enrollment time plus a question or two like what classes did you take last term could easily give a pretty good clue that the person saying the words/phrases is the legitimate student. Given the current market, it seems to be cheaper to deal with breaks after the fact than to expect more from customers. Customers legitimately want actual security without having to care how hash functions work, just like they want safe transportation without having to care about how jet engine turbopumps work. Air travel is pretty safe because if the airline fails to maintain the turbopumps and a plane goes down, there is hell to pay. There is huge legal and financial incentive for travel vendors (airlines) to not cut corners with airplane safety. But vendors who deploy incompetently designed IT systems full of confidential data resulting in massive privacy breaches face no liability at all. There is no financial incentive for them to do it right, so they instead spend the money on more marketing or on executive massages or whatever, and supply lousy security. THAT is the fundamental problem. -- http://mail.python.org/mailman/listinfo/python-list
Make Even More $$$$$ with! GreenZap! Get $25.00 for signing up/$5 for thoose u refer
2005-09-10
Thread
Make More With GreenZap (Better than PayPal)get $25.00/signing up + $5.00/thoose you refer!!!
Make $10,000 in 30 days with GreenZap|Get Paid $25.00/signin up! get paid $5.00/thoose you refer!!! Pay Automated!!! This really does work and is also totally legal and free for anyone to join. Sign up now for free and get $25 instantly into your new account. Why this works Unlike the PayPal $5 programs, this doesn't even cost you $5 to join in, just 2 minutes of your time. Sign up at this link www.greenzap.com/peso4sho $25 will be put into your account for free. Great, you've made $25 in just 2 minutes, not a bad start. Why not turn it into $10,000 or more in just 30 days. Believe me that's a very realistic target. If you're still not convinced try it for the sole reason of proving yourself right for thinking it won't work. But I warn you now, don't start complaining to me with all the money you're making to why I didn't let you know about this sooner. Here's the reason why the're doing this. Pay Pal is their biggest competitor worth $6-8 billion dollars. Pay Pal has between 60-80 million members. In other words, each of those members is worth about $100 to Pay Pal. GreenZap understands this and is willing to pay for its members in advance. That's where the initial $25 comes in as well as the community rewards of anywhere from $5-30 more dollars. This is an ingenious way to quickly build a loyal community of GreenZap members. But remember the're not going to give out the $25 forever. It's only for their pre-registration campaign, so act quickly. They are cheaper to use than PayPal too. $1.00 per transaction fee Compare $1.00 to PayPal's [1.9%-2.9% + $0.30] transaction fees and its easy to see who's focusing on offering value to their community and who's not. Is GreenZap Really Giving Away FREE Money? Yes. Think of it this way; at $1.00/transaction, GreenZap will eventually get their money back once you use your GreenZap account to transact 25 times. How Can You Profit From The Battle Of GreenZap and PayPal? Get started now 1. GET AN EMAIL ACCOUNTI ASSUME YOU ALREADY HAVE ONE... 2.GO TO www.greenzap.com/peso4sho 3. SIGN UP FOR AN ACCOUNT. IT'S TOTALLY FREE AND THEY WILL FUND YOU $25 INSTANTLY INTO YOUR ACCOUNT JUST FOR SIGNING UP. 4. TAKE THAT $25 AND USE IT AS FOLLOWS: CLICK ON THE SEND MONEY TAB. 5.ENTER THE EMAIL ADDRESS IN THE NUMBER ONE POSITION. Here's the current list: 1. [EMAIL PROTECTED] 2. [EMAIL PROTECTED] 3. [EMAIL PROTECTED] SEND THE $25 DOLLARS TO THE FIRST NAME WITH A NOTE SAYING ADD ME TO YOUR MAILING LIST. THEN SEND AN EMAIL TO THE NUMBER THREE POSITION SAYING THANKS I'VE JOINED. THIS SECTION IS IMPORTANT SINCE THIS IS WHAT MAKES THIS LEGAL. YOU CAN SIGN UP FROM ANYWHERE IN THE WORLD AND ONLY ONE ACCOUNT PER PERSON CAN BE OPENED WITH THE GREENZAP SYSTEM SO NO ONE IS ABLE TO SIGN UP FOR LOADS OF ACCOUNTS AND SEND THE $25 TO THEMSELVES. 6. COPY/ PASTE THIS LETTER INTO A WORD PROCESSOR. TAKE THE #1 EMAIL OFF AND PUT YOUR EMAIL YOU SIGNED UP WITH INTO THE #3 POSITION. 7. LOG ON TO GOOGLE OR YAHOO AND TYPE IN MONEY MAKING MESSAGE BOARD OR BUSINESS OPPORTUNITY... ETC. POST THE NEW COPY OF THE LETTER WITH YOUR NAME IN THE 3 SPOT TO LOADS OF MESSAGING BOARDS. THE MORE THE BETTER. YOU CAN ALSO EMAIL THIS LETTER TO ANYONE YOU KNOW, HOW ABOUT SENDING IT TO THE EMAIL ADDRESSES THAT SEND YOU OFFERS. IT'S SIMPLETHE MORE YOU SEND OUT THE MORE MONEY YOU WILL MAKE. AIM TO SEND IT TO AT LEAST 40 PEOPLE. PLEASE DO NOT TRY AND CHEAT BY PUTTING YOUR EMAIL AT THE TOP BECAUSE YOU WILL NOT MAKE A LOT OF MONEY LIKE THAT. REMEMBER YOUR EMAIL ADDRESS WILL BE DELETED FROM THE TOP BY THE NEXT PERSON WHO RECEIVES THIS LETTER. BY STARING AT THE BOTTOM AND BEING MOVED UP WHEN IT'S EMAILED TO OTHERS YOUR EMAIL ADDRESS IT'S EXPOSED TO MANY THOUSANDS MORE AT THE TOP THAN IF YOU CHEAT. That the response rate to this is VERY HIGH goes without saying, really Who else would give you $25 for free and let you use it to make thousands of dollars. You can maybe use the money you make from this program to start you own business or spend this weekend down at your local auto showroom and test drive some cars. Have fun however you spend it! www.greenzap.com/peso4sho Enjoy making lots and lots and lots of money! If you don't try it you will never know. Good fortunes to you and yours. Peso, success wealth! [EMAIL PROTECTED]*PLEASE ADD ME TO YOUR GreenZap LISTS* GZAccepted_Badge2.gif -- http://mail.python.org/mailman/listinfo/python-list
Re: calling command line programs?
On 2005-09-11, Yevgeniy (Eugene) Medynskiy [EMAIL PROTECTED] wrote: This is probably a very newbie question, but after searching google and docs @ python.org I can't find an answer, so maybe someone would be able to help? I'd like to call command-line functions from my python script (like you would in perl using backticks)... Is there a way of doing this? And if so, how does the environment get treated (I have some variables in my env that the programs I'd be calling need to see). Take a look at os.popen, os.spawn, or the popen2, and subprocess modules. That last one seems to be gaining popularity. -- Grant Edwards grante Yow! PEGGY FLEMING is at stealing BASKET BALLS to visi.comfeed the babies in VERMONT. -- http://mail.python.org/mailman/listinfo/python-list
Re: class 'Exception', unable to use 'super' to call superclass initializer
chriss wrote: Hi, environment: Python 2.4, GNU/Linux, kernel 2.6.12.2 having subclassed 'Exception' I'm trying to call the initialiser __init__(...) of the superclass Exception with 'super(..).__init__(..)' . However, trying to do so results in a 'TypeError: super() argument 1 must be type, not classobj'. Now, if I use 'Exception.__init__(..)' instad of super(..)... ,everything works just as one would expect. Why does 'super(..).__init__(..)' fail? AFAICT, the Exception hierarchy are still old-style classes while super() only works on new-style classes. -- Robert Kern [EMAIL PROTECTED] In the fields of hell where the grass grows high Are the graves of dreams allowed to die. -- Richard Harter -- http://mail.python.org/mailman/listinfo/python-list
Re: class 'Exception', unable to use 'super' to call superclass initializer
chriss wrote: Hi, environment: Python 2.4, GNU/Linux, kernel 2.6.12.2 having subclassed 'Exception' I'm trying to call the initialiser __init__(...) of the superclass Exception with 'super(..).__init__(..)' . However, trying to do so results in a 'TypeError: super() argument 1 must be type, not classobj'. Now, if I use 'Exception.__init__(..)' instad of super(..)... ,everything works just as one would expect. Why does 'super(..).__init__(..)' fail? Exceptions do not inherit from 'object'; they are old-style classes. super() can be used only with new-style classes (which subclass 'object'). -Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: calling command line programs?
Yevgeniy (Eugene) Medynskiy wrote: Hi all, This is probably a very newbie question, but after searching google and docs @ python.org I can't find an answer, so maybe someone would be able to help? http://docs.python.org/lib/module-subprocess.html -- Robert Kern [EMAIL PROTECTED] In the fields of hell where the grass grows high Are the graves of dreams allowed to die. -- Richard Harter -- http://mail.python.org/mailman/listinfo/python-list
Re: encryption with python
Paul Rubin http://[EMAIL PROTECTED] writes: Kirk Job Sluder [EMAIL PROTECTED] writes: We're told there is already a secure database in the picture somewhere, or at least one that unescapeably contains cleartext SSN's, so that's the system that should assign the ID numbers and handle SSN-based queries. Well, IMO just having cleartext SSNs is questionable practice unless you need those SSNs to report to some other agency that takes SSNs. And even so, you might want to limit access to plaintext SSNs to a limited group, and give access to the hashed SSNs as a search key to a different group. I think the fundamental problem is that that most customers don't want actual security. They want to be able to get their information by calling a phone number and saying a few words/phrases they memorized in childhood. A voice exemplar stored at enrollment time plus a question or two like what classes did you take last term could easily give a pretty good clue that the person saying the words/phrases is the legitimate student. In my experience the typical student has trouble remembering what happened last week, much less last term. In addition, universities frequently need to field questions from people who were students years ago. Are voice exemplars at that stage yet? Customers legitimately want actual security without having to care how hash functions work, just like they want safe transportation without having to care about how jet engine turbopumps work. Air travel is pretty safe because if the airline fails to maintain the turbopumps and a plane goes down, there is hell to pay. There is huge legal and financial incentive for travel vendors (airlines) to not cut corners with airplane safety. But vendors who deploy incompetently designed IT systems full of confidential data resulting in massive privacy breaches face no liability at all. I'm more than happy to agree to disagree on this, but I see it differently. In aviation there certainly is a bit of risk-benefit analysis going on in thinking about whether the cost of a given safety is justified given the benefits in risk reduction. Likewise, credit companies are currently making money hand-over-fist. If an identity is compromised, it's cheaper for them to just close the account, refund the money, and do their own fraud investigation after the fact. Meanwhile, for every person who gets stung, there are a hundred wanting convenience. In addition, the losses due to bad cryptographic implementation appear to be trivial compared to the losses due to social engineering. -- Kirk Job-Sluder The square-jawed homunculi of Tommy Hilfinger ads make every day an existential holocaust. --Scary Go Round -- http://mail.python.org/mailman/listinfo/python-list
Re: calling command line programs?
Grant Edwards wrote: On 2005-09-11, Yevgeniy (Eugene) Medynskiy [EMAIL PROTECTED] wrote: This is probably a very newbie question, but after searching google and docs @ python.org I can't find an answer, so maybe someone would be able to help? I'd like to call command-line functions from my python script (like you would in perl using backticks)... Is there a way of doing this? And if so, how does the environment get treated (I have some variables in my env that the programs I'd be calling need to see). Take a look at os.popen, os.spawn, or the popen2, and subprocess modules. That last one seems to be gaining popularity. The suggested modules and functions have been deprecated according to the python 2.4 docs. The doc suggests to use the functions in the 'subprocess' module. chriss -- http://mail.python.org/mailman/listinfo/python-list
Re: class 'Exception', unable to use 'super' to call superclass initializer
Peter Hansen wrote: chriss wrote: Hi, environment: Python 2.4, GNU/Linux, kernel 2.6.12.2 having subclassed 'Exception' I'm trying to call the initialiser __init__(...) of the superclass Exception with 'super(..).__init__(..)' . However, trying to do so results in a 'TypeError: super() argument 1 must be type, not classobj'. Now, if I use 'Exception.__init__(..)' instad of super(..)... ,everything works just as one would expect. Why does 'super(..).__init__(..)' fail? Exceptions do not inherit from 'object'; they are old-style classes. super() can be used only with new-style classes (which subclass 'object'). -Peter That explains it all right. Thank you very much for your answer. chriss -- http://mail.python.org/mailman/listinfo/python-list
Re: encryption with python
Kirk Job Sluder wrote: Paul Rubin http://[EMAIL PROTECTED] writes: Kirk Job Sluder [EMAIL PROTECTED] writes: We're told there is already a secure database in the picture somewhere, or at least one that unescapeably contains cleartext SSN's, so that's the system that should assign the ID numbers and handle SSN-based queries. Well, IMO just having cleartext SSNs is questionable practice unless you need those SSNs to report to some other agency that takes SSNs. Colleges generally do have such needs. -- Robert Kern [EMAIL PROTECTED] In the fields of hell where the grass grows high Are the graves of dreams allowed to die. -- Richard Harter -- http://mail.python.org/mailman/listinfo/python-list
Re: encryption with python
On Saturday 10 September 2005 14:01, Kirk Job Sluder wrote: Providing any kind of access to data involves creating a security hole. This is the biggest flaw in most discussions of computer security. On 9/9/05 Steven D'Aprano wrote: There are one-way encryption functions where the result can't easily be traced back to the input, but why do you need the input anyway? Here is my quick-and-dirty student ID algorithm: I have invented the perfect security protocol that solves a major problem with the one-time-pad. The problem with most one-time-pad protocols is that you still need to have the pad around, creating a major security hole. I have solved that problem here. It has all of the steps of the usual one-time-pad plus an extra step. 1. Generate a random number the size of your data. 2. XOR your data with it. 3. Destroy the original data. Here is the additional step: 4. Destroy the random number. You can see now that no adversary can resonably reconstruct the plain text. This protocol might be terribly inconvenient, though, because it makes the origina data unaccessible. Oh well, just a necessary byproduct of theoritcally perfect security. I hereby place this algorithm in the public domain. Use it freely. James -- James Stroud UCLA-DOE Institute for Genomics and Proteomics Box 951570 Los Angeles, CA 90095 http://www.jamesstroud.com/ -- http://mail.python.org/mailman/listinfo/python-list
Re: encryption with python
Kirk Job Sluder [EMAIL PROTECTED] writes: I'm more than happy to agree to disagree on this, but I see it differently. In aviation there certainly is a bit of risk-benefit analysis going on in thinking about whether the cost of a given safety is justified given the benefits in risk reduction. Likewise, credit companies are currently making money hand-over-fist. If an identity is compromised, it's cheaper for them to just close the account, refund the money, and do their own fraud investigation after the fact. You don't get it. Refunding the money improperly charged on a single card doesn't begin to compensate for the hassle of undoing an identity theft. If airlines worked the way you're suggesting the credit industry should work, and a plane went down, the airline would be off the hook by refunding your estate the price of your ticket. It's only because they face much further-reaching liability than that, that they pay so much attention to safety. -- http://mail.python.org/mailman/listinfo/python-list
Re: encryption with python
Kirk Job Sluder wrote: The only way to keep confidential stuff secure is to shred it, burn it, and grind the ashes. I think the fundamental problem is that that most customers don't want actual security. They want to be able to get their information by calling a phone number and saying a few words/phrases they memorized in childhood. Given the current market, it seems to be cheaper to deal with breaks after the fact than to expect more from customers. Security = Privacy in this context, and most customers do want privacy. But also in this case, you are referring to two party security situations, where the data is shared between a service provider and a service consumer. I would think that any n digit random number not already in the data base would work for an id along with a randomly generated password that the student can change if they want. The service provider has full access to the data with their own set of id's and passwords, so in the case of a lost id, they can just look it up using the customers name and/or ssn, or whatever they decide is appropriate. In the case of a lost password, they can reset it and get another randomly generated password. Or am I missing something? Cheers, Ron -- http://mail.python.org/mailman/listinfo/python-list
Re: simple problem with os.rename() parameters - path with spaces
Peter Hansen wrote:
Tom wrote:
Drive E: is removable, so I was careful to verify that that was a factor
in the problem.
Yes, I can do the same renaming, with the same drive, at the command line.
I think I put the emphasis in the wrong place in my question. This
isn't really about os.rename(). It is about putting a filename with
spaces into a string object and then using it as a parameter to an 'os'
command.
That can't really be all there is to the issue, since other people can
successfully use spaces in filenames passed to 'os' commands including
os.rename. There must be something special with _your_ situation. What
else could it be except the file system?
Oh... wait, I see now. Look closely at your error message:
Traceback (most recent call last):
File E:\Music\MoveMusic.py, line 64, in ?
main();
...
File E:\Music\MoveMusic.py, line 49, in Visit
os.mkdir( NewDir );
OSError: [Errno 22] Invalid argument: 'e:\\music.ogg\\Joni
Mitchell\\ogg-8'
Where do you think those double quotation marks came from? What happens
if you try the following instead of using the variables you were trying
to use?
os.rename(e:\\music\\Joni Mitchell\\ogg-8,
e:\\music.ogg\\Joni Mitchell\\ogg-8)
Now try it with this and observe how you get (I predict) the same error
message as you originally got, and note what your mistake was:
os.rename('e:\\music\\Joni Mitchell\\ogg-8',
'e:\\music.ogg\\Joni Mitchell\\ogg-8')
This produced the msg:
OSError: [Errno 22] Invalid argument
I'm now using forward slashes instead of backslashes - this simplifies
things a bit.
The problem seems to be that I'm trying to create more than one
directory at a time. In the above example, the dir 'Joni Mitchell'
doesn't exist.
The functions that I'm calling (os.rename and shutil.move) use mkdir,
not makedirs. The solution is for me to use makedirs with all of the
path except the leaf before I move/rename the old dir.
Thanks for your help,
Tom.
--
http://mail.python.org/mailman/listinfo/python-list
Re: List of integers L.I.S. (SPOILER)
Bryan; My own version also timed out. And now I can tell: it's incredibly SLOW. Nevertheless it would be interesting to compare speed of my code against yours. I can't do it myself because my Python is of 2.3.4 version. Just uncomment your part. import bisect def oops(w,a,b): for m in w: j=bisect.bisect_left(a,m) a.insert(j,m) b.insert(j,max(b[:j]+[0])+1) def n00m(n,w): a,b=[],[] oops(w,a,b) v=map(lambda x: -x, w[::-1]) c,d=[],[] oops(v,c,d) e=map(sum, zip(b, d[::-1])) mx=max(e) f=[] for i in xrange(n): if e[i]==mx: f.append(i+1) print len(f) def one_way(seq): n = len(seq) dominators = [n + 1] * (n * 1) score = [None] * n end = 0 for (i, x) in enumerate(seq): low, high = 0, end while high - low 10: mid = (low + high) 1 if dominators[mid] x: low = mid + 1 else: high = mid + 1 while dominators[low] x: low += 1 dominators[low] = x score[i] = low end = max(end, low + 1) return score def supernumbers(seq): forscore = one_way(seq) opposite = [len(seq) - x for x in reversed(seq)] backscore = reversed(one_way(opposite)) score = map(sum, zip(forscore, backscore)) winner = max(score + [0]) return sorted([seq[i] for i in range(len(seq)) if score[i] == winner]) def b_olson(sequence): supers = supernumbers(sequence) print len(supers) import random, time n=5 w=range(1,n+1) random.shuffle(w) t=time.time() n00m(n,w) print 'n00m:',time.time()-t t=time.time() b_olson(w) print 'b_olson:',time.time()-t -- http://mail.python.org/mailman/listinfo/python-list
Re: Why do Pythoneers reinvent the wheel?
Dennis Lee Bieber wrote: On 10 Sep 2005 05:36:08 EDT, Tim Daneliuk [EMAIL PROTECTED] declaimed the following in comp.lang.python: On a more general note, for all the promises made over 3 decades about how OO was the answer to our problems, we have yet to see quantum OO goes back /that/ far? (2 decades, yes, I might even go 2.5 decades for academia G). My college hadn't even started structured programming (beyond COBOL's PERFORM statement) by the time I graduated in 1980. Well, okay... SmallTalk... But for most of the real world, OO became a known concept with C++ mid to late 80s. OO ideas predate C++ considerably. The idea of encapsulation and abstract data types goes back to the 1960s IIRC. I should point out that OO isn't particularly worse than other paradigms for claiming to be The One True Thing. It's been going on for almost a half century. I've commented on this previously: http://www.tundraware.com/Technology/Bullet/ -- Tim Daneliuk [EMAIL PROTECTED] PGP Key: http://www.tundraware.com/PGP/ -- http://mail.python.org/mailman/listinfo/python-list
Re: First release of Shed Skin, a Python-to-C++ compiler.
Mark Dufour [EMAIL PROTECTED] writes: After nine months of hard work, I am proud to introduce my baby to the world: an experimental Python-to-C++ compiler. Wow, looks really cool. But why that instead of Pypy? -- http://mail.python.org/mailman/listinfo/python-list
Re: encryption with python
In [EMAIL PROTECTED], Steven D'Aprano wrote: last_number_used = 12345 usable_IDs = [] def make_studentID(): global last_number_used global usable_IDs if not usable_IDs: # generate another batch of IDs in random order usable_IDs = range(last_number_used, last_number_used + 1000) - usable_IDs.sort(random.random()) + random.shuffle(usable_IDs) last_number_used += 1000 return usable_IDs.pop() Ciao, Marc 'BlackJack' Rintsch -- http://mail.python.org/mailman/listinfo/python-list
Re: encryption with python
On Saturday 10 September 2005 15:02, Ron Adam wrote: Kirk Job Sluder wrote: I would think that any n digit random number not already in the data base would work for an id along with a randomly generated password that the student can change if they want. The service provider has full access to the data with their own set of id's and passwords, so in the case of a lost id, they can just look it up using the customers name and/or ssn, or whatever they decide is appropriate. In the case of a lost password, they can reset it and get another randomly generated password. Or am I missing something? Yes and no. Yes, you are theoretically correct. No, I don't think you have the OP's original needs in mind (though I am mostly guessing here). The OP was obviously a TA who needed to assign students a number so that they could anonymously check their publicly posted grades and also so that he could do some internal record keeping. But, I'm thinking no one remembers college here anymore. When I was in college (and when I TA'd) security was kind of flimsy. TAs kept all records of SS#s, etc. (etc. includes birthdays here) in a gradebook (or the rich ones kept them on a 5 1/4 floppy). Grades were reported publicly by full SS#s, usually on a centralized cork-board. That was back in the good-ole-days, before financial fraud was euphemised to identity theft. When I TA'd several years later, grades were reported by the last n digits of the SS#. Some very security conscious TAs--or was it just me? I think it was just me--solicited pass phrases from each student and grades were reported based on the student generated pass phrase--and not on SS# or the like. These phrases usually came in the form of Buffs1 or Kitty1979 (the latter possibly revealing some information about a birthday, perhaps?). Some students didn't submit pass phrases, for whatever reason. I think I did the less convenient of the two most reasonable options, which was to withold reporting the grade to the student until they gave me a phrase. The other option was to use a default pass phrase of the last n digits of the SS#. The idea of combining ID information and encrypting it to create another ID is a quantum leap beyond the primitive last n digits of the SS#. Does it beat, in theoretical terms, assigning random numbers? No. And it certainly doesn't beat, in theoretical terms, my improved one-time-pad protocol (see my previous email). I challenge even the most capable cryptographer to beat my improved one-time-pad protocol for security (Oh wait, here it is: 1. Destroy Data.) But it is convenient, especially if you discard the original identifying information and store just the hashes. And as far as collisions go, even if a class of 10,000 gives a 1% chance of collision, who is going to TA a class of 10,000 students. If you can promise that kind of enrolment for any department, much less any single class, there is a job in an Economics department waiting for you out there, my friend. So what would be the alternative to ID information generated IDs? Have a 3xDES encrypted database with the SS# and birthday stored as plain-text? Better keep the encryption protocol secret! Oops. Screwed up already. I figured out the encryption protocol: Encrypt database with 3xDES using a secret key. Dang, security through obscurity. All they have to do is to get that secret key and all those records are easily readable. The point is that *something has to be kept secret* for encryption security to work. Theoretically best would be a passphrase, or a passphrase to a really big key. So, perhaps we could modify the algorithm from a few messages back, in order to address the (assumed) *practical* considerations of the OP's original query: import sha def encrypt(x,y, password): def _dosha(v): return sha.new(str(v)+str(password)).hexdigest() return int(_dosha(_dosha(x)+_dosha(y))[5:13],16) So now what is the criticism? That its still a secret algorithm because the password is secret? James -- James Stroud UCLA-DOE Institute for Genomics and Proteomics Box 951570 Los Angeles, CA 90095 http://www.jamesstroud.com/ -- http://mail.python.org/mailman/listinfo/python-list
Re: encryption with python
James Stroud [EMAIL PROTECTED] writes: Yes and no. Yes, you are theoretically correct. No, I don't think you have the OP's original needs in mind (though I am mostly guessing here). The OP was obviously a TA who needed to assign students a number so that they could anonymously check their publicly posted grades and also so that he could do some internal record keeping. If that's all it's about, it's not a big deal. If it's for some central administrative database that's more of a target, more care is warranted. The idea of combining ID information and encrypting it to create The info to be combined was the student's birthdate. Why would the TA have access to either that or the SSN? import sha def encrypt(x,y, password): def _dosha(v): return sha.new(str(v)+str(password)).hexdigest() return int(_dosha(_dosha(x)+_dosha(y))[5:13],16) So now what is the criticism? That its still a secret algorithm because the password is secret? That's sort of reasonable as long as the password really is secret and you don't mind a small chance of two students getting the same ID number once in a while. If the password is something that a TA types into a laptop when entering grades and which goes away after the course ends, it's not such a big deal. If it's a long-term key that has to stay resident in a 24/7 server through the students' entire time at the university and beyond, then the algorithm is the trivial part and keeping the key secret is a specialized problem in its own right. For example, financial institutions use special, tamper resistant hardware modules for the purpose. Could the OP please say what the exact application is? That might get more useful responses if the question still matters. -- http://mail.python.org/mailman/listinfo/python-list
Re: encryption with python
On Saturday 10 September 2005 16:30, Paul Rubin wrote: The info to be combined was the student's birthdate. Why would the TA have access to either that or the SSN? Speaking as a former TA, we had all that and a little more, if I remember correctly. The why aspect is a little beyond me. James -- James Stroud UCLA-DOE Institute for Genomics and Proteomics Box 951570 Los Angeles, CA 90095 http://www.jamesstroud.com/ -- http://mail.python.org/mailman/listinfo/python-list
[pyparsing] make sure entire string was parsed
How do I make sure that my entire string was parsed when I call a
pyparsing element's parseString method? Here's a dramatically
simplified version of my problem:
py import pyparsing as pp
py match = pp.Word(pp.nums)
py def parse_num(s, loc, toks):
... n, = toks
... return int(n) + 10
...
py match.setParseAction(parse_num)
W:(0123...)
py match.parseString('121abc')
([131], {})
I want to know (somehow) that when I called match.parseString(), there
was some of the string left over (in this case, 'abc') after the parse
was complete. How can I do this? (I don't think I can do character
counting; all my internal setParseAction() functions return non-strings).
STeVe
P.S. FWIW, I've included the real code below. I need to throw an
exception when I call the parseString method of cls._root_node or
cls._root_nodes and the entire string is not consumed.
--
# some character classes
printables_trans = _pp.printables.translate
word_chars = printables_trans(_id_trans, '()')
syn_tag_chars = printables_trans(_id_trans, '()-=')
func_tag_chars = printables_trans(_id_trans, '()-=0123456789')
# basic tag components
sep = _pp.Literal('-').leaveWhitespace()
alt_sep = _pp.Literal('=').leaveWhitespace()
special_word = _pp.Combine(sep + _pp.Word(syn_tag_chars) + sep)
supp_sep = (alt_sep | sep).suppress()
syn_word = _pp.Word(syn_tag_chars).leaveWhitespace()
func_word = _pp.Word(func_tag_chars).leaveWhitespace()
id_word = _pp.Word(_pp.nums).leaveWhitespace()
# the different tag types
special_tag = special_word.setResultsName('tag')
syn_tag = syn_word.setResultsName('tag')
func_tags = _pp.ZeroOrMore(supp_sep + func_word)
func_tags = func_tags.setResultsName('funcs')
id_tag = _pp.Optional(supp_sep + id_word).setResultsName('id')
tags = special_tag | (syn_tag + func_tags + id_tag)
def get_tag(orig_string, tokens_start, tokens):
tokens = dict(tokens)
tag = tokens.pop('tag')
if tag == '-NONE-':
tag = None
functions = list(tokens.pop('funcs', []))
id = tokens.pop('id', None)
return [dict(tag=tag, functions=functions, id=id)]
tags.setParseAction(get_tag)
# node parentheses
start = _pp.Literal('(').suppress()
end = _pp.Literal(')').suppress()
# words
word = _pp.Word(word_chars).setResultsName('word')
# leaf nodes
leaf_node = tags + _pp.Optional(word)
def get_leaf_node(orig_string, tokens_start, tokens):
try:
tag_dict, word = tokens
word = cls._unescape(word)
except ValueError:
tag_dict, = tokens
word = None
return cls(word=word, **tag_dict)
leaf_node.setParseAction(get_leaf_node)
# node, recursive
node = _pp.Forward()
# branch nodes
branch_node = tags + _pp.OneOrMore(node)
def get_branch_node(orig_string, tokens_start, tokens):
return cls(children=tokens[1:], **tokens[0])
branch_node.setParseAction(get_branch_node)
# node, recursive
node start + (branch_node | leaf_node) + end
# root node may have additional parentheses
cls._root_node = node | start + node + end
cls._root_nodes = _pp.OneOrMore(cls._root_node)
--
http://mail.python.org/mailman/listinfo/python-list
Fun with decorators and unification dispatch
Been playing around a bit more with developing my python inference engine, and I thought it might be of general interest (plus, I am finding the criticism useful). My original goal was to brush up on my math skills. Now, I've long felt that the best way to learn a language *thoroughly* is to write a compiler for it. So why not write a compiler for math? However, algebra and calculus aren't just about evaluating an expression and getting the answer, they are about *manipulating* mathematical expressions, applying transformations to them. Systems that do this (such as Mathematica and Yacas) are called computer algebra systems, so I decided to see how hard it would be to implement one in Python. A computer algebra system is essentially a specialized kind of expert system, in other words it is a set of transformation rules, where an input expression is matched against a database of patterns, and the result of the database query determines what transformation is to be made. Most such systems start by implementing their own, specialized programming language, but I wanted instead to see if I could add a inference engine capability to Python itself. So what I have is a dispatch mechanism that maintains a database of Python functions, keyed by the input pattern. Unlike multimethod systems, the input patterns are not merely a list of types, but can be trees containing both constants and variables. Here's a trivial example, using the classic recursive algorithm for computing the factorial of a number: # Declare that Factor is a generic function Factorial = Function() # Define Factorial( 0 ) @Arity( 0 ) def Factorial(): return 1 # Define Factorial( x ) @Arity( MatchInteger.x ) def Factorial( x ): return x * Factorial( x - 1 ) print Factorial( 12 ) Function produces an instance of a generic function, which is a callable object. When called, it searches its list of patterns to determine the function to dispatch. The Arity decorator adds the function as a special case of the generic function. It adds the specific function to the generic's internal pattern database, and also returns the generic function as its return result, so that that (in this case) the name Factorial is bound to the generic function object. MatchInteger is a class that produces a matching object, otherwise known as a bound variable. In this case, the variable's name is x. (It overloads the __getattr__ method to get the variable name.) When the pattern matcher encounters a matching object, it attempts to bind the corresponding portion of the expression to that variable. It does this by adding the mapping of variable name to value into a dictionary of variable bindings. When the function is called, the dictionary of variable bindings is expanded and passed to the function (i.e. func( *bindings )), so that the variable that was bound to x now gets passed in as the x parameter of the function. MatchInteger itself is a type of qualified match (that is, a variable that only binds under certain conditions), and could be defined as: MatchInteger = QualifiedMatch( lambda x: type( x ) is int ) (Although it is not in fact defined this way.) QualifiedMatch takes a list of matching preducates, which are applied to the expression before binding can take place. Here's a more complex example, which is a set of rules for simplifying an expression: Simplify = Function() # x = x @Arity( MatchAny.x ) def Simplify( x ): return x # x * 0 = 0 @Arity( ( Multiply, MatchAny.x, 0 ) ) def Simplify( x ): return 0 # x * 1 = x @Arity( ( Multiply, MatchAny.x, 1 ) ) def Simplify( x ): return Simplify( x ) # x + 0 = x @Arity( ( Add, MatchAny.x, 0 ) ) def Simplify( x ): return Simplify( x ) # x + x = 2x @Arity( ( Add, MatchAny.x, MatchAny.x ) ) def Simplify( x ): return (Multiply, 2, Simplify( x ) ) # General recursion rule @Arity( ( MatchAny.f, MatchAny.x, MatchAny.y ) ) def Simplify( f, x, y ): return ( Simplify( f ), Simplify( x ), Simplify( y ) ) And in fact if I call the function: print Pretty( Simplify( Parse( (x + 2) * 1 ) ) ) print Pretty( Simplify( Parse( x * 1 + 0 ) ) ) print Pretty( Simplify( Parse( y + y ) ) ) print Pretty( Simplify( Parse( (x + y) + (x + y) ) ) ) It prints: x + 2 x 2 * y 2 * (x + y) The argument matcher tries to prioritize matches so that more specific matches (i.e. containing more constants) are matched before more general matches. This is perhaps too unsophisticated a scheme, but it seems to have worked so far. The pattern matcher also looks to see if the object being matched has the commute or associate property. If it finds commute it attempts to match against all posssible permutations of the input arguments (with special optimized logic for functions of one and two arguments). If the associate property is found, it first tries to flatten the expression (transforming (+ a (+ b c)) into (+ a b c), and then generating all possible partitions of the arguments into two sets, before attempting
Re: Why do Pythoneers reinvent the wheel?
[Tim Daneliuk] OO ideas predate C++ considerably. The idea of encapsulation and abstract data types goes back to the 1960s IIRC. Did not Simula-67 have it all already? When C++ came along, much later, I asked someone knowledgeable in the field of language design what was his opinion about C++. He answered very laconically: Simula-- . And this was not far from fully true: Simula had many virtues which are still missing from C++. Moreover, a language like Simula cannot be made up of thin air, it only crystallizes a long maturation of many trends. The term OO may have been coined later, but the concepts were already there. In computer science, I often saw old concepts resurrecting with new names, and then mistaken for recent inventions. New ideas are not so frequent... -- François Pinard http://pinard.progiciels-bpi.ca -- http://mail.python.org/mailman/listinfo/python-list
Re: Fun with decorators and unification dispatch
talin at acm dot org [EMAIL PROTECTED] writes: # Declare that Factor is a generic function Factorial = Function() Was the comment a typo for Factorial? # Define Factorial( 0 ) @Arity( 0 ) def Factorial(): return 1 Overriding old definition of Factorial # Define Factorial( x ) @Arity( MatchInteger.x ) def Factorial( x ): return x * Factorial( x - 1 ) Overriding it again print Factorial( 12 ) I'm confused, how did it know what to do? Are you using some reflection hack in the MatchInteger decorator to figure out the function name? -- http://mail.python.org/mailman/listinfo/python-list
Re: Python compiled?
Robert Kern [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] Terry Reedy wrote: Nor has 386 'machine language' suffered from being interpreted, at a deeper level, by microcode. I think both you and Paul may be missing Tim's point. I don't think he's talking about suffering in technical respects, like speed. He's talking about popularity. I knew that ;-) and meant that ;;--)). Of course, many people don't know that 'machine code' is often now interpreted -- nor that Python code is compiled to something by all current implementations. Perhaps we should call the CPython 'interpreter' the CPython interpreter-compiler that it is. Terry J. Reedy -- http://mail.python.org/mailman/listinfo/python-list
Expected Value
How would I get the expected value out of this information. I have tried many times to understand this but am unable to. The function expectP(z) computes E(X) for the random variable representing a sample over the probability generated by pf for the set of discrete items [1,10]. The constant c is needed so that the probability sum to 1.0, as required by the definition of probability. The function pf(r,c,x) returns the probability that item x will be equal to a randomly chosen variable, denoted by P(x) or P(X=x) in mathematical texts, where c is the constant mentioned above and r is needed because we are considering a power law distribution. The function expectP(z) computes E(X) with r=z, using pf(r,c,x) where x ranges over the set of discrete items in [1,10] The program: def norm(r): calculate normalization factor for a given exponent # the function for this distribution is P(x) = c*(x**-r) # and the job of this norm function is to calculate c based # on the range [1,10**5] sum = 0.0 for i in range(1,1+10**5): # final sum would be more accurate by summing from small values # to large ones, but this is just a homework, so sum 1,2,..10**5 sum += float(i)**-r return 1.0/sum def pf(r,c,x): return a power-law probability for a given value # the function for this distribution is P(x) = c*(x**-r) # where the constant c is such that it normalizes the distribution return c*(float(x)**-r) #- between these lines, define expectP() function - #- end of expectP() definition def showExpectP(limit): display ExpectP(limit) by rounding down to nearest integer k = expectP(limit) return int(k) if __name__ == '__main__': import doctest, sys doctest.testmod(sys.modules[__name__]) -- http://mail.python.org/mailman/listinfo/python-list
Re: Fun with decorators and unification dispatch
Yes, it was a typo. Even thought the function has not yet been bound to the name Factorial when it calls the decorator, the function's __name__ attribute is set to it, so I use that to look up the name of the generic. Here''s the source for Arity: def Arity( *pattern ): A function decorator that defines a specific arity of a generic function. This registers the specific implementation with the generic function (which must be in the global scope.) def inner( f ): if isinstance( f, Function ): generic = f f = generic.last_defined else: name = f.__name__ if not name in f.func_globals: raise Exception( Generic function + name + has not been defined. ) generic = f.func_globals[ name ] generic.name = name generic.last_defined = f generic.add_arity( pattern, f ) return generic return inner There's a couple of kludges here: 1) The Generic doesn't know its own name until you define at least one specialization for it. Otherwise, you would have to say: Factorial = Function( Factorial ) which I consider verbose and redundant. 2) The whole last_defined thing is to allow multiple arities for a single specialized function. Since the arity normally returns the generic, and not the specialized func, as the return value, that means that any additional decorators will be applied to the generic rather than the specialized func. last_defined is a kludge for getting around that, but only for decorators that understand the situation. -- http://mail.python.org/mailman/listinfo/python-list
Re: calling command line programs?
On 2005-09-10, chriss [EMAIL PROTECTED] wrote: Take a look at os.popen, os.spawn, or the popen2, and subprocess modules. That last one seems to be gaining popularity. The suggested modules and functions have been deprecated according to the python 2.4 docs. The doc suggests to use the functions in the 'subprocess' module. The subprocess module is depricated? -- Grant Edwards grante Yow! Did you move a lot at of KOREAN STEAK KNIVES this visi.comtrip, Dingy? -- http://mail.python.org/mailman/listinfo/python-list
Re: How to handle very large MIME Messages with the email package?
[EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] Looking at the email package, it seems all the MIMExxx classes takes string but not file object as the payload. I need to handle very large MIME messages say up to 100M. And possibly many of them. Is email package sufficient. If not is it possible to extend it? I presume so. I am also pretty sure that someone has revised parts of the email package. When the next PyDev summary (for the last half of August) appears, you can check. If so, you might possibly ask the reviser if such an extension has been done or planned. Terry J. Reedy -- http://mail.python.org/mailman/listinfo/python-list
Re: encryption with python
James Stroud wrote: On Saturday 10 September 2005 15:02, Ron Adam wrote: Kirk Job Sluder wrote: I would think that any n digit random number not already in the data base would work for an id along with a randomly generated password that the student can change if they want. The service provider has full access to the data with their own set of id's and passwords, so in the case of a lost id, they can just look it up using the customers name and/or ssn, or whatever they decide is appropriate. In the case of a lost password, they can reset it and get another randomly generated password. Or am I missing something? Yes and no. Yes, you are theoretically correct. No, I don't think you have the OP's original needs in mind (though I am mostly guessing here). The OP was obviously a TA who needed to assign students a number so that they could anonymously check their publicly posted grades and also so that he could do some internal record keeping. But, I'm thinking no one remembers college here anymore. Last semester I took, I was able to check my grades by logging into a web page with my student ID and using a password. The password default was my SSN, we could change it. In any case students have read only access and are not able to change anything. Not a big deal and very little personal information was visible. If any one would have bothered to look they would have simply found out I had very good grades. shrug The point is that *something has to be kept secret* for encryption security to work. Theoretically best would be a passphrase, or a passphrase to a really big key. So, perhaps we could modify the algorithm from a few messages back, in order to address the (assumed) *practical* considerations of the OP's original query: The actual database files should not be directly reachable, except by the appropriate data base administrators, it should send and retrieve information based on the users access rights via a server. Is this a case where each account is encrypted with a different key in addition to the access rights given to each user? Cheers, Ron -- http://mail.python.org/mailman/listinfo/python-list
Re: Python versus Perl
Roy Smith [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] Dieter Vanderelst [EMAIL PROTECTED] wrote: 1 - How does the speed of execution of Perl compares to that of Python? To a first-order approximation, Perl and Python run at the same speed. 'Speed of execution' is a feature of an inplementation, not of languages themselves. Different implementations of Python (for instance, CPython versus CPython+Psyco) can vary in speed by more than a factor of 10 for particular blocks of Python code. (Yes, I know you are comparing the stock standard implementations, but my point still stands.) They are both interpreted languages. To be useful, every language has to be interpreted sometime by something. In the narrow technical sense that I presume you mean, 'interpretation' versus 'compilation' is again an implementation feature, not a language feature. As far as I know, neither Perl nor Python has an implementation that directly interprets in the way that Basic or tokenized Basic once was. I am being picky because various people have claimed that Python suffers in popularity because it is known as an 'interpreted language'. So maybe advocates should be more careful than we have been to not reinforce the misunderstanding. Terry J. Reedy -- http://mail.python.org/mailman/listinfo/python-list
Re: Escaping certain characters
Jan Danielsson wrote:
Robert Kern wrote:
[---]
Hmm... On second thought, I need to escape more characters.
Is there no other way to escape characters in strings?
Which characters?
I need to escape '\n', '', '[' and ']'. I finally went with a few of
these:
string.replace('\n', '\\n')
string.replace('', '\\')
You might like this recipe:
http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/81330
Kent
--
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Re: Python linear algebra module -- requesting comments on interface
Terry Reedy wrote: [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] The module will be public domain. Various lawyers have suggested that either you cannot do that (is US) or that you should not do that. (You know the joke -- ask two lawyers and you get three opinions -- but all depends on your country of residence.) Well he can do it, but you are right, it is best not too. If anything, using an open source license will encourage people to share back any additions or bug fixes they make. ANTLR for example was public domain (still is for version 2), but switched to BSD for version 3: http://www.antlr.org/license.html -- http://mail.python.org/mailman/listinfo/python-list
Re: make sure entire string was parsed
Steven - Thanks for giving pyparsing a try! To see whether your input text consumes the whole string, add a StringEnd() element to the end of your BNF. Then if there is more text after the parsed text, parseString will throw a ParseException. I notice you call leaveWhitespace on several of your parse elements, so you may have to rstrip() the input text before calling parseString. I am curious whether leaveWhitespace is really necessary for your grammar. If it is, you can usually just call leaveWhitespace on the root element, and this will propagate to all the sub elements. Lastly, you may get caught up with operator precedence, I think your node assignment statement may need to change from node start + (branch_node | leaf_node) + end to node (start + (branch_node | leaf_node) + end) HTH, -- Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: List of integers L.I.S. (SPOILER)
[Bryan Olson, on the problem at http://spoj.sphere.pl/problems/SUPPER/ ] I never intended to submit this program for competition. The contest ranks in speed order, and there is no way Python can compete with truly-compiled languages on such low-level code. I'd bet money that the algorithm I used (coded in C) can run with the winners. I also think I'd wager that the Python version outright trumps them on code size. Oh, it's not that bad wink. I took a stab at a Python program for this, and it passed (3.44 seconds). It just barely made it onto the list of best solutions, which I also guess is ranked by elapsed runtime. The Java program right above it took 2.91 seconds, but ate more than 27x as much RAM ;-) I didn't make any effort to speed this, beyond picking a reasonable algorithm, so maybe someone else can slash the runtime (while I usually enjoy such silliness, I can't make time for it at present). I'll include the code below. Alas, without access to the input data they use, it's hard to guess what might be important in their data. On my home box, chewing over random 100,000-element permutations took less than a second each (including the time to generate them); I'm pretty sure they're using slower HW than mine (3.4 GHz P5). My first version bombed for the zero-length sequence. That was a mistake, sorry, but it may not be one of their test-cases. I wonder how many of the accepted entries would perform properly. No idea here, and didn't even think about it. Notes: the `all` returned by crack() is a list such that all[i] is list of all (index, value) pairs such that the longest increasing subsequence ending with `value` is of length i+1; `value` is at index `index` in the input permutation. The maximal LISs thus end with the values in all[-1]. findall() iterates backwards over `all`, to accumulate all the values that appear in _some_ maximal LIS. There's clearly wasted work in findall() (if someone is looking for an algorithmic point to attack). Curiously, no use is made of that values are integers, outside of input and output; any values with a total ordering would work fine in crack() and findall(). # http://spoj.sphere.pl/problems/SUPPER/ def crack(xs): from bisect import bisect_right as find smallest = [] all = [] n = 0 for index, x in enumerate(xs): i = find(smallest, x) if i == n: smallest.append(x) all.append([(index, x)]) n += 1 else: all[i].append((index, x)) if x smallest[i]: smallest[i] = x return all def findall(all): constraints = all[-1] allints = [pair[1] for pair in constraints] for i in xrange(len(all) - 2, -1, -1): survivors = [] for pair in all[i]: index, value = pair for index_limit, value_limit in constraints: if index index_limit and value value_limit: survivors.append(pair) allints.append(value) break constraints = survivors return sorted(allints) def main(): import sys while 1: n = sys.stdin.readline() if not n: break n = int(n) perm = map(int, sys.stdin.readline().split()) assert n == len(perm) supers = findall(crack(perm)) perm = None # just to free memory print len(supers) print .join(map(str, supers)) if __name__ == __main__: main() -- http://mail.python.org/mailman/listinfo/python-list
Re: encryption with python
Paul Rubin http://[EMAIL PROTECTED] writes: Kirk Job Sluder [EMAIL PROTECTED] writes: Likewise, credit companies are currently making money hand-over-fist. If an identity is compromised, it's cheaper for them to just close the account, refund the money, and do their own fraud investigation after the fact. You don't get it. Refunding the money improperly charged on a single card doesn't begin to compensate for the hassle of undoing an identity theft. If airlines worked the way you're suggesting the credit industry should work, and a plane went down, the airline would be off the hook by refunding your estate the price of your ticket. It's only because they face much further-reaching liability than that, that they pay so much attention to safety. Oh, I'm not suggesting the credit industry should work that way. I'm just saying that's the way they will work as long as they can push off the costs for dealing with problems onto interest rates and other fees. -- Kirk Job-Sluder The square-jawed homunculi of Tommy Hilfinger ads make every day an existential holocaust. --Scary Go Round -- http://mail.python.org/mailman/listinfo/python-list
Re: First release of Shed Skin, a Python-to-C++ compiler.
experimental Python-to-C++ compiler.why that instead of Pypy? . pypy compiles to llvm (low-level virtual machine) bytecode which is obviously not as fast as the native code coming from c++ compilers; but the primary mission of pypy is just having a python system that is written in something like python rather than c or c++ . there is no reason why the pypy project can't have a .NET architecture instead of the java-like arrangement I assume it has now . without such a pypy.NET system, shedskin is offering a service that pypy can't yet provide: a ( python - c++ )-conversion allows me to smoothly integrate python contributions with my already-staggering c++ library . I'm not suggesting that pypy should be another Mono rewritten in python, because the essential mission of the .NET architecture is being able to compile any language of the user`s choice, to some intermediate language designed to be far more efficiently compiled to any machine language of the user`s choice than any human-readable language such as c++ . perhaps llvm bytecode can serve as such an intermediate language? then llvm could be the new c++ (our defacto IL (intermediate language)) and shedskin (python - IL=c++) could then be replaced by the combination of pypy (python - IL=llvm) and some incentive for all target platforms to develope a highly optimized ( llvm - native code)-compiler -- assuming also, that there is available a highly optimized ( c++ - llvm bytecode )-compiler . -- American Dream Documentshttp://www.geocities.com/amerdreamdocs/home/(real opportunity starts with real documentation) -- http://mail.python.org/mailman/listinfo/python-list
Re: simple problem with os.rename() parameters - path with spaces
Tom wrote:
Peter Hansen wrote:
Where do you think those double quotation marks came from? What
happens if you try the following instead of using the variables you
were trying to use?
os.rename(e:\\music\\Joni Mitchell\\ogg-8,
e:\\music.ogg\\Joni Mitchell\\ogg-8)
Now try it with this and observe how you get (I predict) the same
error message as you originally got, and note what your mistake was:
os.rename('e:\\music\\Joni Mitchell\\ogg-8',
'e:\\music.ogg\\Joni Mitchell\\ogg-8')
This produced the msg:
OSError: [Errno 22] Invalid argument
Presumably this means the second one, whereas for the first you got a
different message? The latter is clearly invalid, since paths can't
contain quotation marks. The former would work provided the folder
music.ogg/Joni Mitchell existed.
The problem seems to be that I'm trying to create more than one
directory at a time. In the above example, the dir 'Joni Mitchell'
doesn't exist.
If that were true, and the only problem, you would get a different
error: OSError: [Errno 2] No such file or directory
The functions that I'm calling (os.rename and shutil.move) use mkdir,
not makedirs. The solution is for me to use makedirs with all of the
path except the leaf before I move/rename the old dir.
Regardless of the issue with error messages, that sounds like it does
explain your problem. Great! :-)
-Peter
--
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Re: encryption with python
Ron Adam [EMAIL PROTECTED] writes: Kirk Job Sluder wrote: They want to be able to get their information by calling a phone number and saying a few words/phrases they memorized in childhood. Given the current market, it seems to be cheaper to deal with breaks after the fact than to expect more from customers. I would think that any n digit random number not already in the data base would work for an id along with a randomly generated password that the student can change if they want. The service provider has full access to the data with their own set of id's and passwords, so in the case of a lost id, they can just look it up using the customers name and/or ssn, or whatever they decide is appropriate. In the case of a lost password, they can reset it and get another randomly generated password. Or am I missing something? Not really. My suggestion is that in many cases, if the data is being used only as a backup password or authentication token, there is no need for that data to be stored in plaintext. For example, with the ubiquitous mother's maiden name * there is frequently no need to actually have Smith, Jones, or Gunderson in the database. bf65d781795bb91ee731d25f9a68a5aeb7172bc7 serves the same purpose. There are other cases where one-way anonymity is better than a table linking people to randomly generated userIDs. I'd rather use cryptographic hashes for research databases than keep a table matching people to random numbers hanging around. But I'm weird that way. * I think mother's maiden name is a really poor method for backup authentication because for a fair number of people in the U.S., it will be identical to their current surname, and for the rest, it's trivial to discover. Cheers, Ron -- Kirk Job-Sluder The square-jawed homunculi of Tommy Hilfinger ads make every day an existential holocaust. --Scary Go Round -- http://mail.python.org/mailman/listinfo/python-list
Re: Question about consistency in python language
Kay Schluehr wrote: Mike Meyer wrote: Yes, but the function sorted is more useful than a list method sorted in a duck typing language. I don't see what this has to do with duck typing? sorted() is simply a generic function accepting different types. I'm not aware that sorted() requires a specific interface of those types it accepts. Just because you aren't aware of something doesn't stop it being true. The argument must be iterable, and there's a specific protocol for that. The function sorted works on all iterators. I can do: Ah, so you *were* aware of it. def t(n): for i in range(n): yield i ... print sorted(t(5)) and have it work. If sorted were a method of a class - the it'd have to be implemented again for every class iterable class. Either that, or you'd have to create an abstract parent of all iterable classes to add it to - which seems more appropriate for a BD language than Python. Instead of extending a class hierarchy it might even be possible to hook a trait into the class by means of a __traits__ attribute. http://fsl.cs.uiuc.edu/~mhills/presentations/TraitsPresentation.pdf Generators as well as lists and tuples would provide a sortable trait. The sorted() function could remain available for convenience. The advantage being ... ? Perhaps you have just discovered a really interesting hammer, and are seeing this problem as a nail? And even if you do add the abstract class, how do you make my example work without explictly converting the iterator to a list type? I don't know how sorted() is implemented? A naive implementation would in fact be nothing else then: def sorted(iter): l = list(iter) l.sort() return l Kay That would indeed be a naïve implementation. The implementation is, of course, an implementation detail ;-) In this case it requires that sort() then provides all the magic - the need for magic doesn't go away! regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC http://www.holdenweb.com/ -- http://mail.python.org/mailman/listinfo/python-list
getting words from readline
How is best to extract word strings from a line = infile.readline() I wish to quickly check the first word of each line of a text file. Indeed, How do I break a lineinput() line into component words (separate by spaces etc) ? Should I be looking at; Re Parser Slice StringIO ? Any help appreciated. -- http://mail.python.org/mailman/listinfo/python-list
