🌐 Mailman 3 September 2001 - Python-list - python.org

return command in a function.
by Brian Lee Sept. 29, 2001

Sept. 29, 2001

Hi all! I'm newbie at programming and especially Python langauge. What do you think when someone put return, break or continue command in half of a function. I think that commands are like ``goto'' It is very confused for me to understand big code because such commands jump un-excepted line. What do you think about this and how can get be avoid of using such commands? Any advice? -- Brian Lee - http://www.senux.com/

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Re: Singleton Pattern and Python
by wtanksle＠dolphin.openprojects.net Sept. 29, 2001

Sept. 29, 2001

On Thu, 27 Sep 2001 21:51:44 -0000, hungjunglu(a)yahoo.com wrote: >Can someone tell me why not just use a Python module to implement a >singleton pattern? Or better, why is a Python module not considered a >singleton? (That is, why no one ever menthioned about it?) It's a singleton, but it doesn't have a class, can't inherit, and can't be inherited from. It also requires a seperate Python file, and many people prefer single-file scripts. >Hung Jung -- -William "Billy" Tanksley

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Pymacs 0.9
by pinard＠iro.umontreal.ca Sept. 29, 2001

Sept. 29, 2001

Hi! A new release of Pymacs is available as: http://www.iro.umontreal.ca/~pinard/pymacs/pymacs.tar.gz Pymacs allows Emacs users to extend Emacs using Python, where they might have traditionally used Emacs LISP. Pymacs runs on systems having sub-processes. Only one bug was found since last release: `pymacs.Let' now restores a LISP symbol to its previous value rather than to itself. It seems that by now, Pymacs is rather stable and usable, so I'll merely wait for new bugs, needs or ideas to pop up, before making another release. Thanks to all! -- François Pinard http://www.iro.umontreal.ca/~pinard

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Sort documentation inaccurate?
by Bruce Dawson Sept. 29, 2001

Sept. 29, 2001

Or is it the implementation that is peculiar? I'm using PythonWin 2.1 and I tried specifying a user compare function to the list sort() function (so that I could sort file names based on the numerical ordering instead of alphabetical) and I had difficulty getting it working. I assumed without reading the docs carefully (if you search the PythonWin docs for sort you get sparse information anyway) that I could just return the result of a comparison, thusly: >>> mylist = [1, 2, 3, 5, 4, 6] >>> def compare1(x, y): ... return x < y ... >>> mylist.sort(compare1) >>> mylist [1, 2, 3, 5, 4, 6] but it doesn't work. It leaves the list unchanged. Bummer. A few days later (after writing a bubble sort - good thing I had a small list) I was typing in PythonWin when the tooltip for sort() popped up and it said that the return value for the compare function should be 0 or *negative* 1. So I tried this: >>> mylist = [1, 2, 3, 5, 4, 6] >>> def compare2(x, y): ... return -(x < y) ... >>> mylist.sort(compare2) >>> mylist [1, 2, 3, 4, 5, 6] and it works! On closer inspection the documentation says that the compare function is supposed to return -1, 0 or 1. However this seems to be either unnecessary, inaccurate, or both, since returning zero and one had no effect, and returning 0 and -1 sorts the list perfectly. Next time I'll have to read the docs more carefully, but somehow it feels like this could be done better. The behaviour certainly *feels* curious - having to return -(x < y) is a trifle inelegant, and the 'correct' return value of: if x > y: return 1 return -(x < y is cumbersome. In qsort() in the C library the preferred return method is obviously something like: return x - y; but according to both sets of documentation that is illegal in Python, since they specify -1, 0, 1 explicitly. For what it's worth...

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ANN: Interactive Python prompt tools
by Nathaniel Gray Sept. 29, 2001

Sept. 29, 2001

__________________________________________________________________ Announcing: LazyPython v0.5 deep_reload v0.5 Tools for the interactive Python prompt. __________________________________________________________________ WHAT ARE THEY? LazyPython is an exception hook for Python versions 2.1 and later that brings shell escapes, auto-parenthesizing and auto-quoting to the python interactive prompt. deep_reload is an import hook for Python versions 1.5.2 and above that causes the reload() command to act recursively, reloading all of the modules that a given module imports. Together they enhance the convenience of the Python prompt as an interactive environment like, for example, Matlab. HOW DO I USE THEM? Here's an example LazyPython session: >>> import LazyPython Welcome to Lazy Python. Type "help LazyPython" for help. >>> sys.excepthook = LazyPython.LazyPython() >>> >>> # '!' is the shell escape character >>> !pwd /home/n8gray/python >>> !ls CVS gracePlot.py n8utils.pyc Clex.py gracePlot.py.bak pythonstartup.py Heller_inline_message.txt gracePlot.py.bck pythonstartup.py.bck ... snip listing ... >>> >>> # '/' is the auto-paren escape character >>> import gracePlot >>> /reload gracePlot # Look Ma, no parens! --> reload(gracePlot) >>> # When LazyPython rewrites your command line it notifies you with >>> # the line "--> <new-cmd-line>\n\n" >>> >>> # Since reload is a callable, you don't really even have to escape it! >>> reload gracePlot # No '/' or parens --> reload(gracePlot) >>> # ',' is the auto-quote escape character >>> ,some_function arg1 arg2 arg3 --> some_function("arg1", "arg2", "arg3") >>> # You can also specify a list of auto-quote functions that you don't >>> # need to escape. Assuming we have a convenience function 'cp' >>> # that we've specified as an auto-quote function: >>> cp somefile someotherfile # Yes, you could also use a shell escape --> cp("somefile", "someotherfile") >>> Here's how you use deep_reload: >>> import __builtin__, deep_reload >>> __builtin__.reload = deep_reload.reload >>> import Numeric >>> reload Numeric # LazyPython auto-parenning :-) --> reload(Numeric) Reloading Numeric Reloading numeric_version Reloading multiarray Reloading umath ... snip a bunch of other modules ... Reloading copy Reloading org <module 'Numeric' from '/usr/local/[snip...]/Numeric.pyc'> >>> WHY ARE THEY USEFUL? The interactive capability of Python is one of its shining strengths. However, it seems that the interactive prompt was not intended to be the primary working environment for Python programmers and it lacks certain convenience features, like shell escapes, that would enable this usage. As packages such as Matlab demonstrate, though, an interactive prompt can be a very effective working environment, and thanks to advances such as pydoc, Python is achingly close to providing an interactive prompt that one can work at for hours at a time. These files aim to bring the Python prompt closer to dedicated interactive environments such as Matlab in terms of convenience and productivity. Working interactively is much different than writing a program. Every keystroke is precious. This is why the syntax of shells are so different from that of most programming languages. This, plus the utility of shell escapes, is the motivation for LazyPython. Also, when working interactively there are many times when one wishes to reload his entire project at once rather than one module at a time. This is when deep_reload comes in useful. Using these utilities I have successfully and comfortably used Python as an interactive scientific computing environment. WHERE CAN I GET THEM? Both files can be obtained at: http://www.idyll.org/~n8gray/code/index.html __________________________________________________________________ Cheers, -n8 -- Nathaniel Gray California Institute of Technology Computation and Neural Systems --

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Re: Near Final PEP 247 - API for Cryptographic Hash Functions
by Boyd Roberts Sept. 28, 2001

Sept. 28, 2001

"Andrew Kuchling" <akuchlin(a)mems-exchange.org> a écrit dans le message news: mailman.1001707952.19388.python-list(a)python.org... > We program in a byte-oriented world. :) MD5 is _bit_ orientated. > >What exactly does update() do? Does it replace or append? > > "Append", meaning that the string is hashed into the current state of > the object. it has to appended to the current MD5 block. when you have a whole block you can process the block. could you clarify what you just said? the digest is computed on the padded block and it's length: /* pad message */ *me++ = 0x80; if ((me - mb) > MSG_LEN0_BYTE) { /* digest this block and substitute a padded block */ bzero(me, MSG_BYTES - (me - mb)); md5block(mb, digest); bzero(mb, MSG_LEN0_BYTE); } else bzero(me, MSG_LEN0_BYTE - (me - mb)); /* append size in bits */ unpack(bits[0], &mb[MSG_LEN0_BYTE]); unpack(bits[1], &mb[MSG_LEN1_BYTE]); md5block(mb, digest); if you want all the code: http://home.fr.inter.net/boyd/code/md5.bundle

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Any rrdtool.py out there?
by Doug Stanfield Sept. 28, 2001

Sept. 28, 2001

'rrdtool' is an integral tool in the belt of any network manager today. This package, written by Tobi Oetiker (http://people.ee.ethz.ch/~oetiker/), is used to manipulate RRD files. From the home page at http://people.ee.ethz.ch/~oetiker/webtools/rrdtool/: "RRD is the Acronym for Round Robin Database. RRD is a system to store and display time-series data (i.e. network bandwidth, machine-room temperature, server load average). It stores the data in a very compact way that will not expand over time, and it presents useful graphs by processing the data to enforce a certain data density." Unfortunately while there is a Perl binding for the package there doesn't appear to be one for Python, even though the author claims so in the man page documentation. This means there is a body of packages that all use Perl with rrdtool, but nothing done in Python. As well, when I try to customize or pull data out of files, I'm having to use popen and the like from Python. Thats adding some overhead of text processing and manipulation that I'd like to avoid. Is anyone aware of a Python module to manipulate rrd files with the rrdtool package? Failing that, has anyone worked on or looked at what it would take to produce any part of such a module? Thanks, -Doug-

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Re: Sorry!!!!!!!
by Magnus Lie Hetland Sept. 28, 2001

Sept. 28, 2001

<brueckd(a)tbye.com> wrote in message news:mailman.1001533132.13660.python-list@python.org... > The Python collective forgives you! ROTFLMAO! :) -- Magnus Lie Hetland http://www.hetland.org "Reality is that which, when you stop believing in it, doesn't go away." -- Philip K. Dick

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Python embedding & question about autoconf and dynamic linking
by Mads Bondo Dydensborg Sept. 28, 2001

Sept. 28, 2001

Hi there I am trying to use Python as an embedded interprenter. Whilst it is quite easy to understand the C interface, I have found it _very_ hard to figure out what flags I need to pass to the linker to get a succesfull compile. It seems to depend rather heavily on a lot of parameters. So, my first question is if there are any autoconf macros out there that will work for me, sort of like a AM_PATH_SDL macro? I have been searching around, and found one from on of the KDE libs, but it seems to break rather quickly for everything else than Python 1.5 (which it seems to be only partly succesfull in anyway). My next question is with respect to dynamicly linking to the python interprenter, when embedding it. All info I have been able to find, points towards linking statically with libpython.<version>.a - however, this adds about 660KB to my application, and in general I would much rather link to a .so file - but I have not been able to find "such a beast" or instructions on how to build one. Is it possible? Or is there a clever way arond this kind of problem that I - beeing a clueless newbee - have totally overlooked? (Maybe some weird extension trickery?) Thanks in advance! Mads -- Mads Bondo Dydensborg. madsdyd(a)challenge.dk Unix is simple. It just takes a genius to understand its simplicity - Dennis Ritchie

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[development doc updates]
by Fred L. Drake Sept. 28, 2001

Sept. 28, 2001

The development version of the documentation has been updated: http://python.sourceforge.net/devel-docs/ Various small adjustments and bug fixes. Added preliminary docs for the SimpleXMLRPCServer module.

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