Mailman 3 November 2005 - Python-Dev

DRAFT: python-dev Summary for 2005-10-01 to 2005-10-15
by Tony Meyer Nov. 16, 2005

Nov. 16, 2005

As you have noticed, there has been a summary delay recently. This is my fault (insert your favourite thesis/work/leisure excuse here). Steve has generously covered my slackness by doing all of the October summaries himself (thanks!). Anyway, if you have some moments to spare, cast your mind back to the start of October, and see if these reflect what happened. Comments/corrections to tony.meyer(a)gmail.com or steven.bethard(a)gmail.com. Thanks! ============= Announcements =====… [View More]

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DRAFT: python-dev Summary for 2005-09-16 to 2005-09-30
by Tony Meyer Nov. 16, 2005

Nov. 16, 2005

It's been some time (all that concurrency discussion didn't help ;) but here's the second half of September. Many apologies for the delay; hopefully you agree with Guido's 'better late than never', and I promise to try harder in the future. Note that the delay is all my bad, and epithets should be directed at me and not Steve. As usual, please read over if you have a chance, and direct comments/ corrections to tony.meyer(a)gmail.com or steven.bethard(a)gmail.com. (One … [View More]

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Is some magic required to check out new files from svn?
by skip＠pobox.com Nov. 16, 2005

Nov. 16, 2005

Is there some magic required to check out new files from the repository? I'm trying to build on the trunk and am getting compilation errors about code.h not being found. If I remember correctly, this is a new file brought over from the ast branch. Using cvs I would have executed something like "cvs up -dPA ." if I found I was missing something (usually a new directory) and wanted to make sure I was in sync with the trunk. I read the developer's FAQ and the output of "svn up --help". … [View More]

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Conclusion: Event loops, PyOS_InputHook, and Tkinter
by Jim Jewett Nov. 16, 2005

Nov. 16, 2005

Phillip J. Eby: > did you ever try using IPython, and confirm whether it > does or does not address the issue As I understand it, using IPython (or otherwise changing the interactive mode) works fine *if* you just want a point solution -- get something up in some environment chosen by the developer. Michiel is looking to create a component that will work in whatever environment the *user* chooses. Telling users "you must go through this particular interface" is not acceptable. … [View More]

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Behavoir question.
by Scott David Daniels Nov. 16, 2005

Nov. 16, 2005

Since I am fiddling with int/long conversions to/from string: Is the current behavior intentional (or mandatory?): v = int(' 55555555555555555555555555555555555555555 ') works, but: v = int(' 55555555555555555555555555555555555555555L ') fails. --Scott David Daniels Scott.Daniels(a)Acm.Org

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Event loops, PyOS_InputHook, and Tkinter
by Michiel Jan Laurens de Hoon Nov. 15, 2005

Nov. 15, 2005

Dear Pythoneers, I use Python heavily for scientific computing, originally for computational physics and nowadays for computational biology. One of the extension modules I support is pygist, a module for scientific visualization. For this (and similar) packages to work, it is important to have an event loop in Python. Currently, event loops are available in Python via PyOS_InputHook, a pointer to a user-defined function that is called when Python is idle (waiting for user input). … [View More]However, an event loop using PyOS_InputHook has some inherent limitations, so I am thinking about how to improve event loop support in Python. As an example, consider the current implementation of Tkinter. What's nice about it is that events as well as user-typed Python commands are handled without having to call mainloop() explicitly (except on some platforms): "import Tkinter; Tkinter.Tk()" causes a Tk window to pop up that remains responsive throughout. It works as follows (using Tkinter as an example; pygist works essentially the same): 1) Importing Tkinter causes PyOS_InputHook to be set to the EventHook function in _tkinter.c. 2) Before Python calls fgets to read the next Python command typed by the user, it checks PyOS_InputHook and calls it if it is not NULL. 3) The EventHook function in _tkinter runs the following loop: - Check if user input is present; if so, exit the loop - Handle a Tcl/Tk event, if present - Sleep for 20 milliseconds 4) Once the EventHook function returns, Python continues to read the next user command. After executing the command, return to 2). However, this implementation has the following problems: 1) Essentially, the event loop is a busy-wait loop with a 20 ms sleep in between. An event loop using select() (or equivalent on Windows) will give better performance. 2) Since this event loop runs inside Tkinter, there is no way for other extension modules to get their messages handled. Hence, we cannot have more than one extension module that needs an event loop. As an example, it would be nice to have a Tkinter GUI to steer a simulation and a (non-Tk) graphics output window to visualize the simulation. 3) Whereas PyOS_InputHook is called when Python is waiting for user input, it is not called when Python is waiting for anything else, for example one thread waiting for another. For example, IDLE uses two threads, one handling the GUI and one handling the user commands. When the second thread is waiting for the first thread (when waiting for user input to become available), PyOS_InputHook is not being called, and no Tkinter events are being handled. Hence, "import Tkinter; Tkinter.Tk()" does nothing when executed from an IDLE window. Which means that our scientific visualization software can only be run from Python started from the command line, whereas many users (especially on Windows) will want to use IDLE. Now the problem I'm facing is that because of its integration with Tcl, this cannot be fixed easily with Tkinter as the GUI toolkit for Python. If the events to be handled were purely graphical events (move a window, repaint a window, etc.), there would be no harm in handling these events when waiting for e.g. another thread. With Tkinter, however, we cannot enter EventHook while waiting for another thread: a) because EventHook only returns if user input is available (it doesn't wait for threads); b) because EventHook also runs Tcl/Tk commands, and we wouldn't want to run some Tcl commands in some thread while waiting for another thread. Therefore, as far as I can tell, there is no way to set up a true event loop in Python that works nicely with Tkinter, and there is no way to have an event loop function from IDLE. So I'd like to ask the following questions: 1) Did I miss something? Is there some way to get an event loop with Tkinter? 2) Will Tkinter always be the standard toolkit for Python, or are there plans to replace it at some point? I realize that Tkinter has been an important part of Python for some time now, and I don't expect it to be ditched just because of my event loop problems. At the same time, event loop support could use some improvement, so I'd like to call your attention to this issue. Tcl actually has event loops implemented quite nicely, and may serve as an example of how event loops may work in Python. --Michiel. -- Michiel de Hoon Center for Computational Biology and Bioinformatics Columbia University 1150 St Nicholas Avenue New York, NY 10032 [View Less]

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Gothenburg PyPy Sprint II: 7th - 11th December 2005
by Michael Hudson Nov. 15, 2005

Nov. 15, 2005

Gothenburg PyPy Sprint II: 7th - 11th December 2005 ====================================================== (NOTE: internal EU-only sprint starts on the 5th!) The next PyPy sprint is scheduled to be in December 2005 in Gothenborg, Sweden. Its main focus is heading towards phase 2, which means JIT work, alternate threading models and logic programming (but there are also other possible topics). We'll give newcomer-friendly introductions. To learn more about the new PyPy Python-in-Python … [View More]implementation look here: http://codespeak.net/pypy Goals and topics of the sprint ------------------------------ We have released pypy-0.8.0_, which is officially a "research base" for future work. The goal of the Gothenburg sprint is to start exploring new directions and continue in the directions started at the Paris sprint. The currently scheduled main topics are: - The L3 interpreter, a small fast interpreter for "assembler-level" flow graphs. This is heading towards JIT work. - Stackless: write an app-level interface, which might be either Tasklets, as in "Stackless CPython", or the more limited Greenlets. - Porting C modules from CPython. (_socket is not finished) - Optimization/debugging work in general. In particular our thread support is far from stable at the moment and unaccountably slow. - Experimentation: logic programming in Python. A first step might be to try to add logic variables to PyPy. .. _`pypy-0.8.0`: http://codespeak.net/pypy/dist/pypy/doc/release-0.8.0.html Location & Accomodation ------------------------ The sprint will be held in the apartment of Laura Creighton and Jacob Halen which is in Gotabergsgatan 22. The location is central in Gothenburg. It is between the tram_ stops of Vasaplatsen and Valand, where many lines call. .. _tram: http://www.vasttrafik.se Probably cheapest and not too far away is to book accomodation at `SGS Veckobostader`_. (You can have a 10% discount there; ask in the pypy-sprint mailing list for details. We also have some possibilites of free accomodation.) .. _`SGS Veckobostader`: http://www.sgsveckobostader.com Exact times ----------- The public PyPy sprint is held Wednesday 7th - Sunday 11th December 2005. There is a sprint for people involved with the EU part of the project on the two days before the "official" sprint. Hours will be from 10:00 until people have had enough. It's a good idea to arrive a day before the sprint starts and leave a day later. In the middle of the sprint there usually is a break day and it's usually ok to take half-days off if you feel like it. 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). The venue is central in Gothenburg. There is a large selection of places to get food around, from edible-and-cheap to outstanding. You normally need a wireless network card to access the network, but we can 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! There also is a separate `Gothenburg people`_ page tracking who is already thought to come. If you have commit rights on codespeak then you can modify yourself a checkout of http://codespeak.net/svn/pypy/extradoc/sprintinfo/gothenburg-2005/people.txt .. _`PyPy sprint mailing list`: http://codespeak.net/mailman/listinfo/pypy-sprint .. _`Gothenburg people`: http://codespeak.net/pypy/extradoc/sprintinfo/gothenburg-2005/people.html Cheers, mwh -- Speaking from personal experience, I can attest that the barrel of any firearm (or black powder weapon) pointed at one appears large enough to walk down, hands at full extension above the head, without touching the top. -- Mike Andrews, asr [View Less]

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Re: [Python-Dev] Inconsistent behaviour in import/zipimport hooks
by Phillip J. Eby Nov. 14, 2005

Nov. 14, 2005

At 04:33 PM 11/9/2005 -0800, Guido van Rossum wrote: >On 11/9/05, Phillip J. Eby <pje(a)telecommunity.com> wrote: > > By the way, while we're on this subject, can we make the optimization > > options be part of the compile() interface? Right now the distutils has to > > actually exec another Python process whenever you want to compile > > code with > > a different optimization level than what's currently in effect, whereas if > > it could pass the … [View More]

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Re: [Python-Dev] Implementation of PEP 341
by Nick Coghlan Nov. 14, 2005

Nov. 14, 2005

Thomas Lee wrote: > Implemented as you suggested and tested. I'll submit the patch to the > tracker on sourceforge shortly. Are you guys still after contextual > diffs as per the developer pages, or is an svn diff the preferred way to > submit patches now? svn diff should be fine. Although I thought Brett had actually updated those pages after the move to svn. . . > Thanks very much for all your help, Nick. It was extremely informative. I think we can chalk up a … [View More]

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Re: [Python-Dev] Event loops, PyOS_InputHook, and Tkinter
by Edward Loper Nov. 13, 2005

Nov. 13, 2005

As I understand it, you want to improve the performance of interactively run plot commands by queuing up all the plot sub-commands, and then drawing them all at once. Hooking into a python event loop certainly isn't the only way to do this. Perhaps you could consider the following approach: - The plot event loop is in a separate thread, accepting messages from the interactive thread. - These messages can contain plot commands; and they can also contain two new commands: … [View More]

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