Building python packages for the correct architecture on OSX 10.5

[Arnaud Delobelle]

On Nov 14, 7:40 pm, "Martin v. Löwis" <mar... at v.loewis.de> wrote:
> > This means the modules need to be compiles for at least both i386 and
> > x86_64 in my case.
>
> Building Python in 64-bit mode as a universal (fat) binary is not
> supported in Python 2.5, period. So any solution you come necessarily
> has to be a work-around.
>
> The only solution I can see is to make a plain, non-fat installation
> of Python in 64-bit mode, and then use that installation to build
> 64-bit extension modules.
>
> > def Extension(*args, **kwargs):
> >    extra_args = ['-arch', 'ppc', '-arch', 'ppc64',
> >           '-arch', 'i386', '-arch', 'x86_64 ']
>
> This cannot really work, for two reasons:
> a) even if your extension module becomes x86_64 with that mechanism,
>    the Python interpreter itself (i.e. the Python framework) will be
>    purely 32-bit code. So it should not link correctly.

My machine disagrees:

marigold:~ arno$ file /System/Library/Frameworks/Python.framework/
Python
/System/Library/Frameworks/Python.framework/Python: Mach-O universal
binary with 4 architectures
/System/Library/Frameworks/Python.framework/Python (for architecture
ppc7400):	Mach-O dynamically linked shared library ppc
/System/Library/Frameworks/Python.framework/Python (for architecture
ppc64):	Mach-O 64-bit dynamically linked shared library ppc64
/System/Library/Frameworks/Python.framework/Python (for architecture
i386):	Mach-O dynamically linked shared library i386
/System/Library/Frameworks/Python.framework/Python (for architecture
x86_64):	Mach-O 64-bit dynamically linked shared library x86_64


> b) During configure, Python generates a pyconfig.h which has the
>    computed sizes of data types (such as int, long, size_t). It only
>    has a single such file, and the file is generated only during
>    configure. Therefore, the data in it cannot work both for 32-bit
>    and 64-bit architectures. When you compile for a 64-bit target
>    using the 32-bit pyconfig.h, the code may work incorrectly
>    (provided it makes use of the computed values somewhere) (*)
>
> (*) It is surprising that pyconfig.h actually works for both
>     big-endian (ppc) and little-endian (i386) systems, even though
>     it computes the endianness during configure only once. This is
>     due to an OSX-specific hack in pyconfig.h, which hides the
>     definition of the computed endianness value, and uses the
>     value that the compiler provides as a macro instead.

Thanks for the details.
I have had no problems with the modules I have compiled so far, they
have been working in 32 and 64 bits.  Maybe I was just lucky?  I'll
have to look into this more, then.  Python on OSX 10.5 has been a
challenge so far :(

> Regards,
> Martin

Thanks

--
Arnaud