7.5.3 : The C++ module file

Now, let's write the saxpypython.cpp file :

First, we have to activate the numpy we disabled in the previous files. Otherwise, you will get a segmentation fault out of knowhere.
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#define NPY_NO_DEPRECATED_API NPY_1_7_API_VERSION
#ifndef DISABLE_COOL_ARRAY
#define PY_ARRAY_UNIQUE_SYMBOL core_ARRAY_API
#endif
Then, we include all the previous wrapper and the python stuff, of course.
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#include <iostream>

#include <Python.h>
#include "structmember.h"
#include <numpy/arrayobject.h>

#include "saxpyWrapper.h"
It is always good to have a documentation of your function. The folowing will appear when you call a function with '?' or shift-tab in jupyter-notebook :
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std::string saxpyWrapper_docstring = "Compute a Saxpy with aligned table of float32\n\
Parameters :\n\
	tabRes : table of the results (float32 aligned)\n\
	scal : scalar (float32)\n\
	tabX : table of value (float32 aligned)\n\
	tabY : table of value (float32 aligned)\n\
Return :\n\
	Result of the Saxpy as numpy array (tabRes)";
We define the callable method of our wrapper :
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static PyMethodDef _saxpy_methods[] = {
	{"saxpy", (PyCFunction)saxpyWrapper, METH_VARARGS, saxpyWrapper_docstring.c_str()},
	{NULL, NULL}
};
	Notice that you can expose the functions you want, not all the functions you developed.
Now, we have to define the python module itself :
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static PyModuleDef _saxpy_module = {
	PyModuleDef_HEAD_INIT,
	"saxpypython",
	"",
	-1,
	_saxpy_methods,
	NULL,
	NULL,
	NULL,
	NULL
};
Now we define the function which will be called on the import of our module.
	Notice you must call this function PyInit_NameOfYouModule where NameOfYouModule is the name of THIS file.
We create the module, which is a PyObject.
	Do not forget to call import_array otherwise you will get a warning on the best cases and a segmentation fault on your module import.
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///Create the python module saxpy
/**	@return python module saxpy
*/
PyMODINIT_FUNC PyInit_saxpypython(void){
	PyObject *m;
	import_array();
	
	m = PyModule_Create(&_saxpy_module);
	if(m == NULL){
		return NULL;
	}
	return m;
}
The full saxpypython.cpp file :
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/***************************************
	Auteur : Pierre Aubert
	Mail : aubertp7@gmail.com
	Licence : CeCILL-C
****************************************/

#define NPY_NO_DEPRECATED_API NPY_1_7_API_VERSION
#ifndef DISABLE_COOL_ARRAY
#define PY_ARRAY_UNIQUE_SYMBOL core_ARRAY_API
#endif

#include <iostream>

#include <Python.h>
#include "structmember.h"
#include <numpy/arrayobject.h>

#include "saxpyWrapper.h"

std::string saxpyWrapper_docstring = "Compute a Saxpy with aligned table of float32\n\
Parameters :\n\
	tabRes : table of the results (float32 aligned)\n\
	scal : scalar (float32)\n\
	tabX : table of value (float32 aligned)\n\
	tabY : table of value (float32 aligned)\n\
Return :\n\
	Result of the Saxpy as numpy array (tabRes)";

static PyMethodDef _saxpy_methods[] = {
	{"saxpy", (PyCFunction)saxpyWrapper, METH_VARARGS, saxpyWrapper_docstring.c_str()},
	{NULL, NULL}
};

static PyModuleDef _saxpy_module = {
	PyModuleDef_HEAD_INIT,
	"saxpypython",
	"",
	-1,
	_saxpy_methods,
	NULL,
	NULL,
	NULL,
	NULL
};

///Create the python module saxpy
/**	@return python module saxpy
*/
PyMODINIT_FUNC PyInit_saxpypython(void){
	PyObject *m;
	import_array();
	
	m = PyModule_Create(&_saxpy_module);
	if(m == NULL){
		return NULL;
	}
	return m;
}
You can download it here.