Python

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= HOW TO =
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== Modules & Extensions: distutils ==
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* http://docs.python.org/extending/building.html
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* http://docs.python.org/distutils/
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One mention, sometime you get this error message when building your extension under Mac OS X:
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/usr/bin/ld: can't locate file for: -lnameofmylib
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 +
This seems to be a weird problem with Mac OS X where even if the library (here a dynamic library ending with .dylib) is in /usr/lib, it won't be "seen" by the ld linker. To mitigate this problem, create a link in /usr/local/lib/ to the /usr/lib/XXXX.dylib library and add the path in the setup.py file.
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Here is a sample setup.py that fixes that:
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"""
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setup.py
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Created by Philippe Langlois on 2009-11-02.
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Copyright (c) 2009 Philippe Langlois. All rights reserved.
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"""
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from distutils.core import setup, Extension
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setup(name='pysctp',
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version='0.5',
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py_modules=['sctp'],
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ext_modules=[Extension('pysctp', sources=['_sctp.c'],
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include_dirs=['.', '/usr/include'],
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libraries=['sctp'],
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library_dirs=['/usr/lib/', '/usr/local/lib/'],
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)
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],
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data_files=['_sctp.h'],
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author='Elvis Pfutzenreuter',
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author_email='epx __AAAAATTTT_____ epx.com.br',
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maintainer='Philippe Langlois',
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maintainer_email='Philippe.Langlois __AAAAATTT____ gmail.com',
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)

Revision as of 12:08, 2 November 2009

Contents

Intro

This cheat sheet helps troubleshoot common problems...

Some good documentation source:

Tricks

content of objects

Finding what's in an object

>>> dir(obj)

Debugging

See http://pythonconquerstheuniverse.wordpress.com/category/the-python-debugger/

import pdb
pdb.set_trace()


Editor tricks

Emacs

See http://python.about.com/b/2007/09/24/emacs-tips-for-python-programmers.htm

  • C-c <: Shift the region to the left
  • C-c >: Shift the region to the right

HOW TO

Modules & Extensions: distutils

One mention, sometime you get this error message when building your extension under Mac OS X:

/usr/bin/ld: can't locate file for: -lnameofmylib

This seems to be a weird problem with Mac OS X where even if the library (here a dynamic library ending with .dylib) is in /usr/lib, it won't be "seen" by the ld linker. To mitigate this problem, create a link in /usr/local/lib/ to the /usr/lib/XXXX.dylib library and add the path in the setup.py file.

Here is a sample setup.py that fixes that:

"""
setup.py

Created by Philippe Langlois on 2009-11-02.
Copyright (c) 2009 Philippe Langlois. All rights reserved.
"""

from distutils.core import setup, Extension 

setup(name='pysctp',
     version='0.5',
     py_modules=['sctp'],
	  ext_modules=[Extension('pysctp', sources=['_sctp.c'],
	  						 include_dirs=['.', '/usr/include'],
	  						 libraries=['sctp'], 
	  						 library_dirs=['/usr/lib/', '/usr/local/lib/'],
							)
				  ],
	  data_files=['_sctp.h'],
	  author='Elvis Pfutzenreuter',
	  author_email='epx __AAAAATTTT_____ epx.com.br',
         maintainer='Philippe Langlois',
	  maintainer_email='Philippe.Langlois __AAAAATTT____ gmail.com',
     )


Problems

I installed some modules / packages and can't load them

echo $PYTHONPATH
$ python
Python 2.5.2 (r252:60911, Feb 22 2008, 07:57:53) 
[GCC 4.0.1 (Apple Computer, Inc. build 5363)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
for i in sys.path: 
    print i

You can add a .pth file in one of the already loaded dir: see http://djangotricks.blogspot.com/2008/09/note-on-python-paths.html

like:

# cat > /Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packages/others.pth
/Library/Python/2.5/site-packages/
^D
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