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