Re: [Visualpython-users] building failure from visual-5.2_release.tar.bz2 on Mac OS X10.6.4

[Martin C. <cos...@wa...>]

Bruce Sherwood wrote:
> The missing links all seem to be Python symbols such as
> _PyExc_RuntimeError and _PyInt_AsLong, which are part of the Python
> API for connecting to C. I don't have any experience with the darwin
> environment, but maybe someone on this list will recognize what the
> problem is.

It is a problem with python-2.6. There the python executable does not 
export the symbols such as PyExc_RuntimeError any more, as it did until 
python2.5.

Up to python2.5, the external symbols in the python executable were 
identical to those in the python library libpython. The recommended way 
to link python modules on MacOSX (and this is what is coded in 
src/Makefile.in) was to use the "-bundle_loader $PYTHON" flag, meaning 
that symbols in the module were resolved from the python executable. 
Linking with the python library instead led to a runtime error 
"interpreter version mismatch".

On python2.6 (I haven't looked at later versions yet), this is 
different. Now the python executable itself is linked with the python 
library. You need to link the module with the flag "-undefined 
dynamic_lookup" instead of -bundle_loader. At runtime, the symbols are 
then looked up from the python library.

For the Fink visual-py26 package, I am patching src/Makefile.in 
correspondingly. I have not found a way to link cvisualmodule.so that 
would work both with (Fink's) python2.5 and python2.6.

-- 
Martin