9.5.2 : The C++ module file
Now, let's write the barycentrepython.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
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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 "barycentreWrapper.h"
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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 barycentreWrapper_docstring = "Compute a 2d barycentre with aligned table of float32\n\
Parameters :\n\
tabX : table of value (float32 aligned)\n\
tabY : table of value (float32 aligned)\n\
tabA : table of value (float32 aligned)\n\
Return :\n\
barycentre (x, y)";
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We define the callable method of our wrapper :
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static PyMethodDef _barycentre_methods[] = {
{"barycentre", (PyCFunction)barycentreWrapper, METH_VARARGS, barycentreWrapper_docstring.c_str()},
{NULL, NULL}
};
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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 _barycentre_module = {
PyModuleDef_HEAD_INIT,
"barycentrepython",
"",
-1,
_barycentre_methods,
NULL,
NULL,
NULL,
NULL
};
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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 barycentre
/** @return python module barycentre
*/
PyMODINIT_FUNC PyInit_barycentrepython(void){
PyObject *m;
import_array();
m = PyModule_Create(&_barycentre_module);
if(m == NULL){
return NULL;
}
return m;
}
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The full
barycentrepython.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 "barycentreWrapper.h"
std::string barycentreWrapper_docstring = "Compute a 2d barycentre with aligned table of float32\n\
Parameters :\n\
tabX : table of value (float32 aligned)\n\
tabY : table of value (float32 aligned)\n\
tabA : table of value (float32 aligned)\n\
Return :\n\
barycentre (x, y)";
static PyMethodDef _barycentre_methods[] = {
{"barycentre", (PyCFunction)barycentreWrapper, METH_VARARGS, barycentreWrapper_docstring.c_str()},
{NULL, NULL}
};
static PyModuleDef _barycentre_module = {
PyModuleDef_HEAD_INIT,
"barycentrepython",
"",
-1,
_barycentre_methods,
NULL,
NULL,
NULL,
NULL
};
///Create the python module barycentre
/** @return python module barycentre
*/
PyMODINIT_FUNC PyInit_barycentrepython(void){
PyObject *m;
import_array();
m = PyModule_Create(&_barycentre_module);
if(m == NULL){
return NULL;
}
return m;
}
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You can download it
here.