Cython 3: my own .c source file

Yet more on elementary Cython. I have a working example with my own C code, thanks to help from the Cython users' list (here)---see the UPDATE below for one small change:

hello2.c:

#include <stdio.h> void f(); void f() { printf("%s", "Hello world!\n"); }

hello2_caller.pyx:

cdef extern from "hello2.c": void f() cpdef myf(): f()

setup.hello2_caller.py:

from distutils.core import setup from distutils.extension import Extension from Cython.Distutils import build_ext sourcefiles = ['hello2_caller.pyx'] ext_modules = [Extension("hello2_caller", sourcefiles )] setup( name = 'Hello2 app', cmdclass = {'build_ext': build_ext}, ext_modules = ext_modules )

build it:

python setup.hello2_caller.py build_ext --inplace

import and use it:

>>> import hello2_caller >>> hello2_caller.myf() Hello world!

The compiler complains:

In file included from hello2_caller.c:219: hello2.c:3: warning: function declaration isn’t a prototype hello2.c:5: warning: function declaration isn’t a prototype

But it works.

UPDATE: the problem is that these two declarations are not the same:

void f(); void f(void);

and we need to have the second one.

$ python setup.hello2_caller.py build_ext --inplace running build_ext cythoning hello2_caller.pyx to hello2_caller.c building 'hello2_caller' extension creating build creating build/temp.macosx-10.6-universal-2.6 gcc-4.2 -fno-strict-aliasing -fno-common -dynamic -DNDEBUG -g -fwrapv -Os -Wall -Wstrict-prototypes -DENABLE_DTRACE -arch i386 -arch ppc -arch x86_64 -pipe -I/System/Library/Frameworks/Python.framework/Versions/2.6/include/python2.6 -c hello2_caller.c -o build/temp.macosx-10.6-universal-2.6/hello2_caller.o gcc-4.2 -Wl,-F. -bundle -undefined dynamic_lookup -arch i386 -arch ppc -arch x86_64 build/temp.macosx-10.6-universal-2.6/hello2_caller.o -o hello2_caller.so

$ python Python 2.6.1 (r261:67515, Jun 24 2010, 21:47:49) [GCC 4.2.1 (Apple Inc. build 5646)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> import hello2_caller >>> hello2_caller.myf() Hello world!