🌐 Mailman 3 August 2006 - Python-list - python.org

Python Embedding Questions
by Sean Ryan Aug. 1, 2006

Aug. 1, 2006

Hi Guys, I have a couple of questions (and some concerns) about embedded python within my application. The application is a multi-threaded relatively complex c++ middleware Solaris 9 based application. A decision was made some time ago to provide some scripting capabilities and python was selected as the scripting language. As such, an interpreter was embedded within the application and threading was managed using PyEval_SaveThread, PyEval_RestoreThread and friends. The application switches between python and c++ many, many times during the execution of one business request - typically the flow will be c++ -> python -> c++ -> python -> c++ -> python etc (roughly 60 - 40 split in terms of coverage) Originally python2.2.1 was embedded within the application - we now have a business case (performance being a primary driver) to move to python2.4(.2). We are having some stability issues (random core dumps), and in an attempt to track down the root cause I executed some stress tests under a purify environment and noticed the following : Python2.4.2 trips quite a few ABR (array bounds read) and FMR (free memory read) violations - python2.2.1 less so. purify notes the following as the innermost frames for a FMR. frame_dealloc [frameobject.c:76] PyEval_EvalCodeEx [ceval.c:2596] fast_function [ceval.c:3161] Is this a known issue with embedded python? I can trigger a similar crash with python 2.2.1 in a stress test environment. At this stage, I am getting very concerned about our implementation of embedded python and wondered : 1. Is our use of python as an embedded language commonplace? 2. Does anyone have names of commerical applications that use python in this way 3. Are we switching between python and c++ code too frequently (as many as 40 times in the execution of 1 request) 4. Are there any consultants / contractors that we could engage to aid debugging our application / implementation. 5. Are the warnings that purify is raising related to loss of stability in the application 6. Is python the correct choice for an embedded application (I am aware of the GIL issue) We need to make a concise decision very quickly regarding our use of python, and as such would appreciate the community's honest opinion. Best regards, Sean

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Re: Python-list Digest, Vol 35, Issue 10
by Paul McGuire Aug. 1, 2006

Aug. 1, 2006

Can someone PLEASE remove support(a)mathworks.co.uk from the subscriber list???

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Reinstalling Python Problem (Newbie)
by beno Aug. 1, 2006

Aug. 1, 2006

It's been years since I've done this. I had a programmer working for me who disappeared one day, and now I'm taking over his responsibilities. I need to re-configure Apache for mod_python which means I have to rebuild python. I'm working with the latest distro. I'm heavily dependent on zope, so all this has to work together. Platform is FreeBSD 5.? I have the following questions: What is meant by pointing to this folder thus: ./configure --prefix=/usr/python When I run make test I get these errors: 2 tests failed: test_mimetools test_urllib2 48 tests skipped: test_aepack test_al test_applesingle test_asynchat test_bsddb test_bsddb3 test_cd test_cl test_codecmaps_cn test_codecmaps_hk test_codecmaps_jp test_codecmaps_kr test_codecmaps_tw test_curses test_doctest test_fork1 test_gdbm test_gl test_imgfile test_imp test_linuxaudiodev test_logging test_macfs test_macostools test_nis test_normalization test_ossaudiodev test_pep277 test_plistlib test_queue test_scriptpackages test_socket test_socket_ssl test_socketserver test_sunaudiodev test_tcl test_thread test_threaded_import test_threadedtempfile test_threading test_threading_local test_threadsignals test_timeout test_unicode_file test_urllib2net test_urllibnet test_winreg test_winsound 13 skips unexpected on freebsd5: test_threadedtempfile test_imp test_threaded_import test_fork1 test_threading test_threadsignals test_socket test_thread test_queue test_asynchat test_doctest test_threading_local test_logging *** Error code 1 I've googled this with no luck. Please advise what to do or at least how to start TIA, beno

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Re: Working with Widget after Instance loses the reference
by Al in Dallas Aug. 1, 2006

Aug. 1, 2006

John McMonagle wrote: > On Mon, 2006-07-31 at 11:15 -0700, Al in Dallas wrote: [example of "losing" a widget] > Consider the following code run in the python shell: > > >>> from Tkinter import * > >>> r = Tk() > >>> b1 = Button(r, text='test') > >>> b1.pack() > >>> b2 = Button(r, text='test2') > >>> b2.pack() > >>> r.children > {'-1210160564': <Tkinter.Button instance at 0xb7de6a4c>, '-1210225748': > <Tkinter.Button instance at 0xb7dd6bac>} > >>> r.slaves() > [<Tkinter.Button instance at 0xb7dd6bac>, <Tkinter.Button instance at > 0xb7de6a4c>] > >>> b1 = 'xxx' > >>> b1.destroy() > Traceback (most recent call last): > File "<stdin>", line 1, in ? > AttributeError: 'str' object has no attribute 'destroy' > >>> b1 = r.slaves()[0] > >>> b1.destroy() > >>> > > > So, as long as you know what your widget instance is in root.slaves() or > root.children you can assign it to a new name. Since I've been leaving my shell open, I jumped in and tried: recoveredlabel = root.slaves()[6] And after I verified I could manipulate the widget with that name, I executed: <original-widget-name> = recoveredlabel Now the only difference between where I was (before I screwed up) and where I am is that I've got this extra variable named "recoveredlabel." Thanks. Now, do you have any advice on learning the syntax for dealing with Tix megawidgets in Python? I guess my alternative is to learn how to use Elmer or SWIG so I can hide all the Python I've inherited "under the hood" and write my GUI in Tcl/Tk.

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Re: Nested function scope problem
by danielx Aug. 1, 2006

Aug. 1, 2006

Gerhard Fiedler wrote: > On 2006-07-30 09:54:14, Antoon Pardon wrote: > > > Aren't you looking too much at implementation details now? > > Possibly, but at this point I'm still trying to understand how Python does > these things, and what the useful abstraction level is for me. I also still > have very little experience how I'll put the things we've been discussing Sorry I've been away from this sub-thread for a while (even though I kinda started it :P). Yes, I'm also wondering what difference this big huge argument makes on how I logically follow Python. Personally, I find this metaphor in "Head First Java" from O'Reilly Press really helpful for both Python and Java. Before anyone sends me a letter bomb that says "Python != Java", let me say this: have phun :P. Anyway, the metaphor goes something like this: variables (for objects, not primitives) are like cups (just wait, it gets better). You can put a remote control IN a cup. The remote control controls a "real" object on the heap (ie, the data for the object is there). Unfortunately, some of the effect of the metaphor is lost because I cannot reporduce the very nice illustrations which came in the book :P. Other than the fact that you declare variables in Java (going down another letter-bomb-laden slippery slope), which means they stick around even when they have no "remote controls", I pretty much think of Python variables the same way: each variable LOGICALLY contains a reference (ie, without regard to what the mechanics are) to some amorphous glob of data, sitting on the heap. Therefore, when I do an assignment, I am simply replacing the reference my variable is holding. According to the metaphor, we are replacing the remote control our cup is holding. If an object is no longer visible (because all the references have disappeared), then it should get garbage collected eventually. But until the magical garbage-collecting angle of death makes is way through the heap, our orphaned objects are PHYSICALLY still there until they are forcefully evicted from memory. Logically, however, they were gone as soon as we lost sight of them. Java aside, My question is this: how will using this metaphor break the way I logically follow Python? > here into (Python) practice. While not new to programming, I'm new to > Python. > > > AFAIU, one can also build a C++ class hierarchy that with some small > > limitations in used operators, would have semantics very similar to > > Python. Would you argue that those using such a C++ class hierarchy would > > no longer be using variables in C++? > > Probably not. But for me it's mostly about useful terminology, not > necessarily "correct" terminology. In order to talk about correct > terminology, we'd have to use a common definition of "variable". This is a > term so widely used that I'm not sure there is a useful single definition > of it; do you know one? This is another thing I was thinking the entire time I was reading this argument, but I didn't want someone to answer me in a condescending tone on what exactly a variable IS. I guess I should attribute that quote to Bill Clinton :P. > > In any case, the following doesn't seem to be implementation detail (and > rather a part of the language), but it's not really understandable with a > C++ concept of "variable": > > >>> a=3 > >>> id(a) > 3368152 > >>> b=a > >>> id(b) > 3368152 > >>> b=4 > >>> id(b) > 3368140 > > You don't expect the "identity" of the variable b to change with a simple > assignment from a C/C++ point of view. You also don't expect the "identity" > of a and b to be the same after assigning one to the other. You can create > C++ classes that behave like that (you can implement Python in C++ :), but > that doesn't mean that you expect C++ language constructs to behave like > that. I'm really not comfortable with C, but I disagree. What would you say about this program: #include <stdio.h> #include <stdlib.h> #include <string.h> #define tf(bool) (bool) ? "true" : "false" const char * greeting = "hello world"; int main() { /* These mallocs don't really need to be hear for me to make my point, because as far as I know, what they return is garbage values anyway :P. I just put them there so my pointers are pointing to "real objects".*/ char * string = (char *) malloc(sizeof(char)*100); char * letterBomb = (char *) malloc(sizeof(char)*100); strcpy(string, greeting); strcpy(letterBomb, greeting); printf("are we equal? %s\n", tf(strcmp(string, letterBomb) == 0)); printf("are we IDENTICAL? %s\n", tf(string == letterBomb)); printf("sabotage...\n"); letterBomb = string; printf("are we identical NOW? %s\n", tf(string==letterBomb)); } > > Gerhard

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Re: Release: DirectPython 0.5
by david_wahler＠bic.ky Aug. 1, 2006

Aug. 1, 2006

I'll be out of the office until approximately August 20th. If you have any questions, please email support(a)bic.ky. -- David Wahler

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Re: [ANN] LibYAML-0.0.1: The initial release
by david_wahler＠bic.ky Aug. 1, 2006

Aug. 1, 2006

I'll be out of the office until approximately August 20th. If you have any questions, please email support(a)bic.ky. -- David Wahler

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looking for a regular expression
by shadowcaster.bbs＠bbs.wretch.cc Aug. 1, 2006

Aug. 1, 2006

I want words between 2 nearby commas with a specific word in them. For example,in the text blow: "We the people of the United States, in order to form a more perfect union, establish justice, insure domestic tranquility,......" I want "justice" and the words between the 2 nearest commas, which is establish justice All I can come up with is r",(.*?justice.*?)," but the result is in order to form a more perfect union, establish justice Apreciate any help. -- [1;30;40m夫兵者不祥之器物或惡之故有道者不處君子居則貴左用兵則貴右兵者不祥之器非君子[m [1;30m之器不得已[37m[30m而用之恬淡為上勝而不美而美之者是樂殺人夫樂殺人者則不可得志於天下 [m[1;30m矣吉事尚左凶事尚右偏將軍居左上將軍居右言以喪禮處之殺人之眾以哀悲泣之戰勝以[m [1;30m喪禮處之道常[37m無名[30m樸雖小天下莫能臣侯王若能守之萬物將自賓天地相合以降甘露民莫[m [1;30m之令而自均始制有名名亦既有夫亦將知 [37m210-64-83-81.adsl.dynamic.seed.net.tw[30m海[m 作者在[36m 06/08/01 21:35:48 [37m從[36m 210-64-83-81.adsl.dynamic.seed.net.tw [37m修改這篇文章作者在[36m 06/08/01 21:36:28 [37m從[36m 210-64-83-81.adsl.dynamic.seed.net.tw [37m修改這篇文章作者在[36m 06/08/01 21:37:08 [37m從[36m 210-64-83-81.adsl.dynamic.seed.net.tw [37m修改這篇文章作者在[36m 06/08/01 21:38:04 [37m從[36m 210-64-83-81.adsl.dynamic.seed.net.tw [37m修改這篇文章

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Re: first book about python
by John Salerno Aug. 1, 2006

Aug. 1, 2006

wesley chun wrote: > if you want a large case study (tons of > examples, i.e., everything *plus* the kitchen sink), look for Lutz' > massive Programming Python. which is also coming out in a new edition soon

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Re: Can't get LCHARVAR's with InformixDB
by fhurley＠gmail.com Aug. 1, 2006

Aug. 1, 2006

Carsten Haese wrote: > What version are you using? I thought I fixed lvarchars a long time ago. 2.2, with Python 2.4 on Windows... I installed via InformixDB-2.2.win32-py2.4.exe I can see the data with other tools... it's multi-line, stuff like stack traces, etc., and many start with newlines... but whatever it is, I'm consistently getting empty strings.

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