Mailman 3 June 2005 - Python-Dev

Re: [Python-Dev] PEP 343 - next steps
by Andrew Koenig 13 Jun '05

13 Jun '05

> > But I cannot do this: > > > > def f(x as (a, b)): > > # ... > > which is what I was suggesting. > Yeah, I knew that. How important is that to you? I would really have liked it for a program I was working on at one time that had lots of small methods that passed around values of forms such as (a,(b,c)). Each method would pick one or more of the components out of its compound value and then would sometimes pass the entire value down to the next level. Of course I could do it this way: def f(x): (a,(b,c)) = x # ... but in this particular application, "as" would have offered significant extra convenience. I understand that this is not a real big deal, which is why I haven't written up a PEP :-)

1 0

Summer of Code: Developing complete SSL support for Python
by Florencio Cano Gabarda 13 Jun '05

13 Jun '05

Hello, This is my first post to the list but I wish to be an active developer of Python in the future. This project of Summer of Code from Google has opened my eyes to the open source community. The money has been a great motivation but thinking about coding something that will be remembered in the future and specially USEFUL to the community motivates me very much too. After this introduction I want to talk about SSL support in Python. I have read in the Summer of Code section of Python web that a possible project is coding a new complete module that implements SSL to Python. And possibly add this module to the python standard library. Appart from this the project would include adding functionality to the modules (like urlib) to support SSL as trasparent as possible. ¿What do you think about it? **I'm actually looking for information in the archives of this list and web** but I would like to ask the list something: - Is necessary a complete new SSL module for Python? - What do you need about SSL ? - What do you think about incorporing SSL to act trasparently in the modules that use it in the actuality ? - Any kind of information, references, would be appreciate. I would like to do the new SSL module as good as possible. A piece of art and efficiency if possible and obviusly having in mind all programming standards. Thanks very much for any help. -- Florencio Cano Gabarda <fcano(a)ono.com>

5 4

Re: [Python-Dev] Multiple expression eval in compound if statement?
by Michael Chermside 13 Jun '05

13 Jun '05

Skip writes: > Even an apparently simple variable can have side effects [...] Consider > the builtin help object. Type it at the prompt with no parens. I tried. As far as I can tell, the result (in the interactive interpreter) is the same as with any other object except None: the _ variable gets set, the interpreter prints out the __str__ of the object, sets the _ variable, and prints a new '>>>' prompt. It happens that the __str__ of the help object is: 'Type help() for interactive help, or help(object for help about object.' ... but if there's some side effect going on here, I don't see it. What am I missing? -- Michael Chermside

2 1

Re: [Python-Dev] Multiple expression eval in compound if statement?
by Michael Chermside 13 Jun '05

13 Jun '05

A few thought's on Skip's idea here: Skip: > I can't imagine anyone relying on a side-effect when evaluating x in this > context, and if someone did, their code would be truly fragile. Yeah... people like that really annoy me. If people just wouldn't write code that depends on the FULL dynamics possible, then it'd be a lot easier for the VM to optimize. Unfortunately, we have to support such people. Raymond: I think it unwise to allow x to be any expression. Besides altering existing semantics, it leads to code redundancy and to a fragile construct (where the slightest alteration of any of the expressions triggers a silent reversion to O(n) behavior). Skip's proposal isn't the problem here. The syntax of the if-elif-else statement requires that when it is used in lieu of C's switch() statement that the switch() argument be repeated in each elif clause. Repeating it DOES violate once-and-only-once, but we've decided that that's an acceptable price to pay to avoid needing an extra kind of flow control statement for which there wasn't a really elegent syntax anyhow. A reasonably tradeoff, I agree, but the cost is that we DO violate once-and-only-once. The REAL danger from the "slightest alteration of any of the expressions" is not that it will alter from O(1) behavior to O(n) behavior, the REAL danger is that you may have MEANT it to be the same everywhere and the alteration is a typo and a bug! Guido: > I think it would be wiser if you only did this when x is a simple > local variable. I agree. I think of Skip's proposal as just an optimization, of the sort that the Python interpreter is allowed to make when there's no possible semantic effect. It would then restrict the use to situations where the 'switch() argument' was a local variable and the 'case values' were string literals, integer literals, float literals (but that shouldn't count because it's a really bad idea anyhow), None, and perhaps (I wouldn't bother, myself) tuples of the above. It sounds pretty restricted, which raises the question of whether it's worth it given the harsh restrictions on when the optimization would kick in. I write such things with local variables and literal strings quite often. On the other hand, I don't usually have more than 4-10 values though, so O(1) and O(n) may not be THAT different. It's one of those cases where the only thing I'd really believe was experiments done on real code. But it's a cool optimization if it actually pays off. -- Michael Chermside

1 0

[ANN] Have fun programming with your kids
by ducasse 12 Jun '05

12 Jun '05

Hi If you are a parent, an educator or a programmer having kids this is for you! After 4 years of work, my new book "Squeak: Learn programming with Robots" will be out soon. http://smallwiki.unibe.ch/botsinc/ http://www.amazon.com/exec/obidos/tg/detail/-/1590594916/ qid=1117218524/sr=1-1/ref=sr_1_1/002-5642974-5143261?v=glance&s=books With Bots Inc you will learn how to program robots in an interactive environment. Bots Inc proposes three teaching approaches: direct command of robots, scripting robots and programming robots. The book contains 24 chapters going step by step over topics with a lot of examples. Bots Inc is fun but it is not a toy, it teaches you 100% real programming. Bots Inc is built on top of the rich open-source multimedia Squeak environment that you can also discover. My goal is to explain key elementary programming concepts (such as loops, abstraction, composition, and conditionals) to novices of all ages. I believe that learning by experimenting and solving problems with fun is central to human knowledge acquisition. Therefore, I have presented programming concepts through simple but not trivial problems such as drawing golden rectangles or simulating animal behavior. The ideal reader I have in mind is an individual who wants to have fun programming. This person may be a teenager or an adult, a schoolteacher, or somebody teaching programming to children in some other organization. Such an individual does not have to be fluent in programming in any language. As a father of two young boys I also wrote this book for all the parents that want to have fun programming with their kids in a powerful interactive environment. Programming in Squeak is an interactive, fun but deep experience. The present book teaches elementary programming aspect, the following book will introduce a new fun environment and teach object-oriented programming. Testimonies "I am using the version of the book on your web site to teach my oldest daughter Becca some programming. She absolutely loves it. We are doing the Bot graphics right. My other kids are showing interest as well. My Fall semester schedule leaves me with almost no time free but in the Spring I hope to bring Squeak and your book to our elementary school's "gifted" program." C. David Shaffer "I'm using the Bot Lab environment for three years and found it really valuable in teaching computer science concepts for a young audience (and even less young !). The bots commanded through balloon (as in comic strips) is a very nice introduction for young children, and when this aspect is well understood, you can use the Bot Workspace to teach the notion of script, a first step in programming languages. The Micro Browser allows children to add new behavior for their bots, and have fun with their creation. This three-layers tool - Balloon, Micro Workspace, Micro Browser - offers to the teacher a fun way to introduce gently the basis of object-oriented programming concepts. With Bots Inc, learning is playing ! ;-)" Samir Saidani - University of Caen - France "I recently started a course with 7th-graders (age about 13 years) with Stephane's book --- they love it. They all know about syntactic issues from maths --- in a way they know that an expression in a formal language must be well formed. So they easily grasp the fact such as "there must be a colon after the message-name if an argument follows". Of cause they don't really read the error-messages, they just see "there must be some error" and they remember the simple rules. Don't underestimate Smalltalk --- it's easy understandable because it has a simple and straight-forward design." Klaus Fuller - Germany Have fun... Stef http://www.iam.unibe.ch/~ducasse/ "if you knew today was your last day on earth, what would you do different? ... especially if, by doing something different, today might not be your last day on earth" Calvin&Hobbes

2 1

Post-EuroPython 2005 PyPy Sprint 1st - 7th July 2005
by Armin Rigo 12 Jun '05

12 Jun '05

Post-EuroPython 2005 PyPy Sprint 1st - 7th July 2005 ====================================================== The next PyPy sprint is scheduled right after EuroPython 2005 in Gothenborg, Sweden. Its main focus is translation to lower level backends but there are also other possible topics. We'll give newcomer-friendly introductions. To learn more about the new PyPy Python-in-Python implementation look here: http://codespeak.net/pypy On a side note, there are a number of sub projects that may be interesting for participating in google's summer-of-code event (deadline June 14th!). The PyPy group is willing to mentor projects that have some link with PyPy, so if you are accepted in such a project, the sprint could also serve as a good meeting and kick-off point. Further down you'll find some examples, but there are certainly more and bigger ones :-) Goals and topics of the sprint ------------------------------ The main, though not the only, focus of the sprint will be on the "translation" aspect of PyPy. The goal here is to progress towards a completely translated PyPy. How much will already have been done before EuroPython is unknown; as a guess, we will be left with: - completing the "rtyper", the piece of code that assigns low-level C-like types to high-level RPython objects (lists, dicts, instances, etc.) and low-level control flow graphs to high-level ones; - polish off the GenC and GenLLVM back-ends, responsible for turning the low-level C-like flow graphs into real C or LLVM source code. See http://codespeak.net/pipermail/pypy-dev/2005q2/002136.html for more information (10th of June status). Non-translation-related topics are welcome too. Here are some suggestions from the issue tracker (https://codespeak.net/issue/pypy-dev/): - integrate the parser module, possibly making it RPython conformant; - rewrite in Python a C module you are familiar with (partial list of missing/incomplete modules: os, math, array, regular expressions, binascii...) - implement Python 2.3's import hook extensions (zip-imports etc.) - fix Windows-related issues, '%'-formatting rounding errors, add missing docstrings on app-level built-in types and functions, etc. - weakrefs (but this requires discussion and planning on pypy-dev before the sprint! feel free to start such a discussion, though.) Location & Accomodation ------------------------ The sprint will be held in the former Math Center building near the crossing of Gibraltargatan and Eklandagatan. Entrance is on the middle of the side facing Gibraltargatan. The doors to the building are normally locked, so you need the phone number of somebody inside to get in. Instructions on whom to call will be posted on the door. The sprint will be co-located with several other sprints. See the `EuroPython Wiki`_, to find out what other sprints will be running. Nearest, and probably cheapest is to book accomodation at SGS Veckobostäder through the Europython website. This option will be available until about 20 June. .. _`EuroPython special accomodation`: http://www.europython.org/sections/accomodation/special_accomodation .. _`EuroPython Wiki`: http://www.europython.org/sections/sprints_and_wiki Exact times ----------- The public Pypy sprint is held Friday 1st July - Thursday 7 July 2005. Hours will be from 09:00 until people have had enough. It's a good idea to arrive a day before the sprint starts. (There is a sprint for people who are familiar with the Pypy codebase before Europython as well. This will be held at Jacob & Laura's home on Götabergsgatan 22.) Network, Food, currency ------------------------ Sweden is not part of the Euro zone. One SEK (krona in singular, kronor in plural) is roughly 1/10th of a Euro (9.15 SEK to 1 Euro). There are some pizzerias, kebab places and the like close to the venue. Their food is edible and cheap, but not very good. For good food, you need to go downtown. You need a wireless network card to access the network. You will be issued a login to the Chalmers NOMAD network. This will allow you to use access points all over Chalmers. However, we can likely provide a wireless/ethernet bridge. Sweden uses the same kind of plugs as Germany. 230V AC. Registration etc.pp. -------------------- Please subscribe to the `PyPy sprint mailing list`_, introduce yourself and post a note that you want to come. Feel free to ask any questions there! .. _`PyPy sprint mailing list`: http://codespeak.net/mailman/listinfo/pypy-sprint -- Armin Rigo & the PyPy team

1 0

hashlib - faster md5/sha, adds sha256/512 support
by Gregory P. Smith 12 Jun '05

12 Jun '05

I have finished up the hashlib work I started on in feb/march for patch 1121611 and 935454 after some discussion on this list. The full patch including tests and module documentation has been posted in the sf patch 1121611 as hashlib-008. I believe it is done and ready and would like to commit it after a review. Let the reviewing begin! For easy viewing, here's what the module documentation looks like: http://electricrain.com/greg/hashlib-py25-doc/module-hashlib.html The code is in the hashlib-008.patch file: http://redirx.com/?3e19 hashlib incorporates both the 1121611 openssl hash support and the 935454 sha256+sha512 module support into a single hashlib module that picks the fastest implementation of each algorithm to use. OpenSSLs implementations of md5 and sha1 are nearly 2x as fast as the existing python builtin versions. The (now legacy) md5 and sha modules are turned into simple stubs that use hashlib. The actual sourceforge patch tracker entries: https://sourceforge.net/tracker/?func=detail&aid=1121611&group_id=5470&atid… https://sourceforge.net/tracker/?func=detail&aid=935454&group_id=5470&atid=… Greg

1 0

b32encode and NUL bytes
by Pavel Pergamenshchik 11 Jun '05

11 Jun '05

Hi. Is this a feature? I do see b32encode padding the string with NULs first. >>> b32decode(b32encode('\x00')) Traceback (most recent call last): File "<stdin>", line 1, in ? File "/usr/lib/python2.4/base64.py", line 228, in b32decode last = binascii.unhexlify(hex(acc)[2:-1]) TypeError: Odd-length string

3 2

Five patch reviews & patch request
by Michiel De Hoon 10 Jun '05

10 Jun '05

Recently, I reviewed the following five patches: [ 827386 ] absolute paths cause problems for MSVC [ 1161914 ] python-config [ 1187396 ] Add const specifier to PySpam_System prototype [ 1196895 ] in IDLE, assume new text files are python source by default [ 1196917 ] change recall in IDLE shell to not overwrite current command Below are the summaries of the patch reviews. I'd like to ask your attention to this patch: [ 1049855 ] PyOS_InputHook inconsistency on Windows Kurt Kaiser has already looked at this patch, but was hesitant to check it in because he wasn't able to test it on Windows. I'd be happy to send a compiled Python for Windows to anybody willing to have a look at this patch. Thanks! --Michiel. Patch review summaries: ----------------------- [ 827386 ] absolute paths cause problems for MSVC Solves an inconsistency between distutils' msvccompiler.py and ccompiler.py. I am surprised by how absolute paths are handled in ccompiler.py, so I'm not wholeheartedly in favor of copying this behavior to msvccompiler.py. [ 1161914 ] python-config Currently, the patch seems to be broken. Better integration with distutils is needed. Can't recommend this patch in its current form. [ 1187396 ] Add const specifier to PySpam_System prototype This error is already fixed in Revision 1.33 of python/dist/src/Doc/ext/extending.tex. Patch can be closed. [ 1196895 ] in IDLE, assume new text files are python source by default When going to File > New in IDLE, currently IDLE assumes that the new file is a generic text file. With the patch, IDLE assumes that the new file contains python source code by default, and uses syntax highlighting. Whereas currently syntax highlighting is switched on as soon as the file is saved as *.py, after the patch syntax highlighting is not switched off if the file is saved as *.txt. So the patch does not seem to be perfectly OK. [ 1196917 ] change recall in IDLE shell to not overwrite current command I agree that this patch makes IDLE easier to use. Recommend applying this patch. Michiel de Hoon Center for Computational Biology and Bioinformatics Columbia University 1150 St Nicholas Avenue New York, NY 10032

2 1

Bug day on the 25th?
by A.M. Kuchling 10 Jun '05

10 Jun '05

It seems like a good idea to have another Python bug day. Saturday June 25th seems the most practical date (this coming weekend is too soon, and the weekend after is a minor holiday -- Father's Day). We'd convene in the usual place: the #pydotorg IRC channel, on irc.freenode.net. Assuming no one can think of a reason why the 25th would be unsuitable, I'll send an announcement to c.l.py.a in a few days. --amk

2 2