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gcc compile / link questions

Edward C. Jones
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#1: Jul 18 '05
I compile and link Python extension modules using the script

gcc -fPIC -g -I/usr/local/include/python2.3 \
-Wall -Wstrict-prototypes -c mymodule.c
g++ -shared mymodule.o -L/usr/local/lib -o mymodule.so

It works for me but it isn't pretty. Is there a better way to write it?

Gcc finds all the libraries that need to be linked in. For example,
"/usr/local/lib/python2.3/site-packages/numarray/libnumarray.so". How
does gcc do this?

I created a .so file "utilities.so" that contains some C functions that
are called in mymodule.c but are not visible from Python. Both
"utilities.c" and "mymodule.c" use numarray. What changes do I make in
the script above? Must I use the nasty "libnumarray_UNIQUE_SYMBOL" trick?

What is a script for creating "utilities.a" using gcc? How do I change
the script above to include "utilities.a"?


Martin v. Löwis
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Posts: n/a
#2: Jul 18 '05

re: gcc compile / link questions


"Edward C. Jones" <edcjones@erols.com> writes:
[color=blue]
> I compile and link Python extension modules using the script
>
> gcc -fPIC -g -I/usr/local/include/python2.3 \
> -Wall -Wstrict-prototypes -c mymodule.c
> g++ -shared mymodule.o -L/usr/local/lib -o mymodule.so
>
> It works for me but it isn't pretty. Is there a better way to write it?[/color]

Yes, you should write a setup.py using distutils.
[color=blue]
> Gcc finds all the libraries that need to be linked in. For example,
> "/usr/local/lib/python2.3/site-packages/numarray/libnumarray.so". How
> does gcc do this?[/color]

I doubt this statement. gcc does not find things in
/usr/local/lib/python2.3. Why do you think it does?
[color=blue]
> I created a .so file "utilities.so" that contains some C functions
> that are called in mymodule.c but are not visible from Python. Both
> "utilities.c" and "mymodule.c" use numarray. What changes do I make in
> the script above? Must I use the nasty "libnumarray_UNIQUE_SYMBOL"
> trick?[/color]

You cannot access symbols from different extension modules; each
module has its own, separate, space of symbols. If you want to invoke
functions in a different module, you must do so through the Python
API.

Some extension modules provide a CObject containing the API; if
numarray offers such a thing, you should use it.

Regards,
Martin
Closed Thread