calling Pyrex results from C

[François Pinard]

[Kyler Laird]

> I realize that the goal of Pyrex is to create a module that can be
> called from Python.

Or vice-versa.  I found Pyrex useful for calling Python modules from
within C programs which were not Python-aware to start with.  You may
even write wholly Pyrex programs.

> I've discovered that as long as everything in the code is cdef-ed,
> I can call Pyrex code from my C code.  If, however, I so much as
> mention anything Pythonish, it segfaults during execution.

There is some magic needed to establish Python context, not much.
Hoping that it will help, here is a template I use when generating
Pyrex main programs. `%(module)s' shall be replaced by the Pyrex module
name, as Pyrex needs to initialise itself.  When Python calls Pyrex,
initialisation occurs automatically at `import' time, but when C
initially calls Pyrex, initialisation should be explicitly launched.



cdef extern void Py_Initialize()
cdef extern void Py_Finalize()
cdef extern void init%(module)s()

cdef extern int main(int argc, char **argv):
    cdef int index, status
    Py_Initialize()
    init%(module)s()
    import sys
    try:
        arguments = []
        for index from 0 <= index < argc:
            arguments.append(argv[index])
        sys.argv = arguments
        result = main_application()
        raise SystemExit, result or 0
    except SystemExit, result:
        result = str(result)
        try:
            status = int(result)
        except ValueError:
            if not result.endswith('\n'):
                result = result + '\n'
            sys.stderr.write(result)
            status = 1
    except:
        import traceback
        traceback.print_exc()
        status = 1
    Py_Finalize()
    return status


-- 
François Pinard   http://www.iro.umontreal.ca/~pinard