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/* Copyright (C) 2009 Canonical Ltd
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/* This file contains helper functions for exporting a C API for a CPython
* extension module.
*/
#ifndef _EXPORT_C_API_H_
#define _EXPORT_C_API_H_
static const char *_C_API_NAME = "_C_API";
/**
* Add a C function to the modules _C_API
* This wraps the function in a PyCObject, and inserts that into a dict.
* The key of the dict is the function name, and the description is the
* signature of the function.
* This is generally called during a modules init_MODULE function.
*
* @param module A Python module (the one being initialized)
* @param funcname The name of the function being exported
* @param func A pointer to the function
* @param signature The C signature of the function
* @return 0 if everything is successful, -1 if there is a problem. An
* exception should also be set
*/
static int
_export_function(PyObject *module, char *funcname, void *func, char *signature)
{
PyObject *d = NULL;
PyObject *c_obj = NULL;
/* (char *) is because python2.4 declares this api as 'char *' rather than
* const char* which it really is.
*/
d = PyObject_GetAttrString(module, (char *)_C_API_NAME);
if (!d) {
PyErr_Clear();
d = PyDict_New();
if (!d)
goto bad;
Py_INCREF(d);
if (PyModule_AddObject(module, (char *)_C_API_NAME, d) < 0)
goto bad;
}
c_obj = PyCObject_FromVoidPtrAndDesc(func, signature, 0);
if (!c_obj)
goto bad;
if (PyDict_SetItemString(d, funcname, c_obj) < 0)
goto bad;
Py_DECREF(d);
return 0;
bad:
Py_XDECREF(c_obj);
Py_XDECREF(d);
return -1;
}
/* Note:
* It feels like more could be done here. Specifically, if you look at
* _static_tuple_c.h you can see some boilerplate where we have:
* #ifdef STATIC_TUPLE_MODULE // are we exporting or importing
* static RETVAL FUNCNAME PROTO;
* #else
* static RETVAL (*FUNCNAME) PROTO;
* #endif
*
* And then in _static_tuple_c.c we have
* int setup_c_api()
* {
* _export_function(module, #FUNCNAME, FUNCNAME, #PROTO);
* }
*
* And then in _static_tuple_c.h import_##MODULE
* struct function_definition functions[] = {
* {#FUNCNAME, (void **)&FUNCNAME, #RETVAL #PROTO},
* ...
* {NULL}};
*
* And some similar stuff for types. However, this would mean that we would
* need a way for the C preprocessor to build up a list of definitions to be
* generated, and then expand that list at the appropriate time.
* I would guess there would be a way to do this, but probably not without a
* lot of magic, and the end result probably wouldn't be very pretty to
* maintain. Perhaps python's dynamic nature has left me jaded about writing
* boilerplate....
*/
#endif // _EXPORT_C_API_H_
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