[Plplot-devel] Python on Mac OS X, Cygwin, and MinGW

[Alan W. I. <ir...@be...>]

I have just cvs committed the latest version of ac_python_devel.m4 which
provides an interesting extra macro called PYTHON_EXTRA_LDFLAGS. It appears
this is the flag used when python itself is linked. Anyhow, the current CVS
HEAD status is the value of PYTHON_EXTRA_LDFLAGS is completely ignored after
it is determined. However, it is possible that macro telling how python was
linked might prove important on other platforms.

For example, I believe at one point Koen van der Drift was having
difficulties getting python to dynamically load our PLplot python extension
module on Mac OS X. The problem was missing python symbols. I am not sure
whether that was ever resolved or whether Koen abandoned python for his fink
package.

Anyhow, I encourage those developers with access to Mac OS X, Cygwin, or
MinGW to try the python interface to PLplot, and if it doesn't dynamically
load properly from python because of missing symbols, then you might want to
try relinking that module by hand with extra linker flags determined by the
following python command:

python  -c "import distutils.sysconfig; \
conf = distutils.sysconfig.get_config_var; \
print conf('LINKFORSHARED')"

That's copied right from the new ac_python.m4 file and returns the string
"-Xlinker -export-dynamic" on my python-2.3.5 Linux system.  (As expected,
that's also the result for PYTHON_EXTRA_LDFLAGS on my platform.) Of course,
other platforms will have different results depending on how python was
linked. Obviously, the extra linking flags aren't needed on Linux, but it
might be worth experimenting with them on other platforms (and also seeing
what the linker man page says about the flags) if there are currently any
linking troubles for python.

Alan
__________________________
Alan W. Irwin
email: ir...@be...
phone: 250-727-2902

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state implementation
for stellar interiors (freeeos.sf.net); PLplot scientific plotting software
package (plplot.org); the Yorick front-end to PLplot (yplot.sf.net); the
Loads of Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
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Linux-powered Science
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