🌐 Mailman 3 October 2003 - Python-list - python.org

Capturing/Recognizing Text In Another Window
by Scott Brady Drummonds Nov. 16, 2003

Nov. 16, 2003

Hello, everyone, I'd like to write a Python program that could capture the contents of another Windows program and analyze the resultant bitmap. First, I have no idea how to capture another window. Second, I'm not even certain if this graphical problem is a Python issue or a Windows issue. Can anyone offer me some guidance on this? Thanks, Scott -- Remove ".nospam" from the user ID in my e-mail to reply via e-mail.

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PEP 289: Generator Expressions (please comment)
by python＠rcn.com Nov. 15, 2003

Nov. 15, 2003

Peter Norvig's creative thinking triggered renewed interest in PEP 289. That led to a number of contributors helping to re-work the pep details into a form that has been well received on the python-dev list: http://www.python.org/peps/pep-0289.html In brief, the PEP proposes a list comprehension style syntax for creating fast, memory efficient generator expressions on the fly: sum(x*x for x in roots) min(d.temperature()*9/5 + 32 for d in days) Set(word.lower() for word in text.split() if len(word) < 5) dict( (k, somefunc(k)) for k in keylist ) dotproduct = sum(x*y for x,y in itertools.izip(xvec, yvec)) bestplayer, bestscore = max( (p.score, p.name) for p in players ) Each of the above runs without creating a full list in memory, which saves allocation time, conserves resources, and exploits cache locality. The new form is highly expressive and greatly enhances the utility of the many python functions and methods that accept iterable arguments. Raymond Hettinger

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'while' in list comprehension?
by jsaul Nov. 13, 2003

Nov. 13, 2003

Hi there, wouldn't it be useful to have a 'while' conditional in addition to 'if' in list comprehensions? foo = [] for i in bar: if len(i) == 0: break foo.append(i) would then turn into foo = [ i for i in bar while len(i)>0 ] Is there any reason for not having this kind of thing? I actually miss it pretty often. Cheers, jsaul

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LAID (was: python libs v lisp coolness?
by mike420＠ziplip.com Nov. 12, 2003

Nov. 12, 2003

Joe Marshall <prunesquallor(a)comcast.net> wrote in <he1qryba.fsf(a)comcast.net>: > Kenny Tilton <ktilton(a)nyc.rr.com> writes: > >> I don't know. Maybe I'm wrong. If Lisp is such a great language and >> people love it so much, how come they don't write any code? > > Between python bashing and attempting pull static typer's heads out > of their asses, who has the time? (By the way is it "static typist" or "static typer" ?) Lispers need to cooperate with others on libraries. Maybe a Consortium of Underdog Dynamically-Typed Languages needs to be started. Underdog languages are more interested in libraries and cooperation. For each library, a language-agnostic interface description (in LAID language, of course) should be generated by porters, so that later FFIs could be produced for each language automatically. This is the opposite (and complementary to) SWIG: SWIG auto-generates dumb interface information and needs a lot of human post-work for each specific language. "Are you guys having trouble with that GTK lib? - No, we got LAID!"

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BIG successes of Lisp (was ...)
by mike420＠ziplip.com Nov. 8, 2003

Nov. 8, 2003

In the context of LATEX, some Pythonista asked what the big successes of Lisp were. I think there were at least three *big* successes. a. orbitz.com web site uses Lisp for algorithms, etc. b. Yahoo store was originally written in Lisp. c. Emacs The issues with these will probably come up, so I might as well mention them myself (which will also make this a more balanced post) a. AFAIK Orbitz frequently has to be shut down for maintenance (read "full garbage collection" - I'm just guessing: with generational garbage collection, you still have to do full garbage collection once in a while, and on a system like that it can take a while) b. AFAIK, Yahoo Store was eventually rewritten in a non-Lisp. Why? I'd tell you, but then I'd have to kill you :) c. Emacs has a reputation for being slow and bloated. But then it's not written in Common Lisp. Are ViaWeb and Orbitz bigger successes than LATEX? Do they have more users? It depends. Does viewing a PDF file made with LATEX make you a user of LATEX? Does visiting Yahoo store make you a user of ViaWeb? For the sake of being balanced: there were also some *big* failures, such as Lisp Machines. They failed because they could not compete with UNIX (SUN, SGI) in a time when performance, multi-userism and uptime were of prime importance. (Older LispM's just leaked memory until they were shut down, newer versions overcame that problem but others remained) Another big failure that is often _attributed_ to Lisp is AI, of course. But I don't think one should blame a language for AI not happening. Marvin Mins ky, for example, blames Robotics and Neural Networks for that.

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Re: Why I love Python: More rambling...
by Ville Vainio Nov. 8, 2003

Nov. 8, 2003

Andy Jewell <andy(a)wild-flower.co.uk> writes: > Python does seem to magnify the flaws in other languages: everything else > seems (to me at least) to be second-best now. This might be one of the reasons they don't teach Python in schools - it would be hard for the employers to motivate students to work w/ the crappy languages the companies expect them to use. Another aspect of motivation is accomplishment - a thing that might make a C++ programmer proud of his achievement seems like a trivial 15 minute job for a Pythonista, and when that Pythonista is tasked w/ the C++ job he doesn't get the kick from the accomplishment. And 6 hours of debugging that "trivial" program doesn't help either. -- Ville Vainio http://www.students.tut.fi/~vainio24

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ANN: vb2py online code conversion
by Paul Paterson Nov. 7, 2003

Nov. 7, 2003

The Online Version of vb2py has been released. You can now convert Visual Basic (and to a limited extent VBA, VBScript and ASP) to Python code right from your browser without having to download any additional libraries or software. The online version is based on the v0.2 codebase which includes all VB control structures and most intrinsic functions and keywords. Form layout conversion is not currently available in the online version. You can access the online version here: http://vb2py.sourceforge.net/demo.htm What is vb2py? ============== vb2py is a toolkit to aid in the conversion of Visual Basic projects to Python. The aim of the conversion is to match, as closely as possible, the original VB applications both in terms of code behaviour and form layout. Version 0.2 comprises a basic layout converter (converting to PythonCard) with a comprehensive code translation. The project roadmap (http://vb2py.sourceforge.net/roadmap.htm) shows the project's development timeline. Converting VB to Python turns your VB projects into cross platform developments and allows full access to all Python's extensive library of modules. Limitations of the online version ================================= - No form layouts - A limit of 500 LOC per go to prevent server overload - Single files only - No project level global/public variable mapping - **Please note** there are important disclaimers on the site regarding **security** of your code (it is submitted in plain text and is not therefore suitable for commercially sensitive material). Getting the Software ==================== * The main website: http://vb2py.sourceforge.net * The online version: http://vb2py.sourceforge.net/demo.htm * Download the current version: http://vb2py.sourceforge.net/downloads.htm * Documentation: http://vb2py.sourceforge.net/documentation.htm Requirements for the online version =================================== * A web browser Licence ======= vb2py is released under the BSD licence. Release History =============== 0.1 (July 9, 2003) - The first release from the project - a basic form layout translator 0.1.1 (August 1, 2003) - A bugfix release for 0.1 0.2 (September 8, 2003)- First implementation of the full VB parser Online (October 14, 2003) - Online version made available Contributors Welcome ==================== This project would not be possible without the help and support of many people. Anyone who wants to get involved is more than welcome to participate in coding, testing, giving advice, etc. Some particular areas of interest right now are, - testing on large VB projects - testing on Mac - testing out with VBScript, VBA In the meantime I would like to thank all those who supported and contributed towards the project. ---- Paul Paterson vb2py :: A Visual Basic to Python Conversion Toolkit http://vb2py.sourceforge.net

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Explanation of macros; Haskell macros
by mike420＠ziplip.com Nov. 7, 2003

Nov. 7, 2003

I think others dropped the ball while trying to explain macros to non-Lispers recently. The examples I saw posted were either too difficult or easily doable without macros (maybe even easier). This probably convinced many Pythonistas that Lispers are complexity-seeking wackos, and macros are cruft. This only applies to some people and *their* macros. Most important, all of the examples failed to relate to "the common man" : typical python user or programming newbie. As they say, "if you can't explain it ..." I intend to correct this. The following example relates to a problem familiar to all Python users and demonstrates two uses of macros: syntax improvement and efficiency gain through compile-time code introspection. Let's say you do not have the "for" keyword, but you have "dolist" for iterating a list and "dotimes" - a simple index loop. You want to create "for" just like in Python, and you also want "for i in range(10000): print i" to be efficient and avoid constructing the big list (maybe you do not have enough memory). In Lisp, you can acomplish this with the following macro: (defmacro for(i in list &rest rest) (if (eql 'in in) (if (and (listp list) (eql (length list) 2) (eql 'range (first list)) (integerp (second list))) `(dotimes (,i ,(second list)) ,@rest) `(dolist (,i ,list) ,@rest)) (error "syntax error"))) You can use it like this: (for k in (range 10000) (print k)) or (for k in '(666 222 333 111) (print "foo") (print k)) The macro works by looking at *code* (not values) at *compile-time*, and if the right argument is (range xxxx), it uses the more efficient "dotimes". Let me know if the above helped you understand the usefulness of macros or was just as sucky as the earlier stuff. BTW, I think Alex made some very good points about simplicity and uniformity. I hesitate to say that I agree with the final verdict, but his reasoning is very sound. Lispers who tried to mock him (some outside CLP) just showed their own idiocy. This isn't winning Lisp any friends... Someone pointed out that Haskell has macros. Does anyone know how they relate to Lisp and Scheme macros? Better, worse, different? If anyone knows them well, can you show how you would do "for i in ...." using Haskell macros?

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Python versus VB
by simon＠uggs.demon.co.uk Nov. 6, 2003

Nov. 6, 2003

I am meeting with a potential client next week to discuss starting a new project. His preference is for VB whereas I would prefer Python for obvious reasons ;-) Could anybody come up with a short list of the pros and cons of the two languages (I am not terribly familiar with the strengths/weaknesses of VB). This will be a general-purpose text-processing type application with no GUI required. -- Simon Foster Somewhere in the West of England

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Python shortcut ?
by Santanu Chatterjee Nov. 6, 2003

Nov. 6, 2003

Hello everybody, I am very new to Python. So pardon me if this question is too dumb. Suppose I have the following list: myList = [('a','hello), ('b','bye')] How do I get only the first element of each tuple in the above list to be printed without using: for i in range(len(myList)): print myList[i][0] or: for i in myList: print i[0] I tried: print myList[:][0] but it seems to have an altogether different meaning. Regards, Santanu

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