Importing numpy C API¶
Importing the C API module of numpy requires more code than just including a header. xtensor-python
simplifies a lot
this import, however some actions are still required in the user code.
Extension module with a single file¶
When writing an extension module that is self-contained in a single file, its author should pay attention to the following points:
FORCE_IMPORT_ARRAY
must be defined before including any header ofxtensor-python
.xt::import_numpy()
must be called in the function initializing the module.
Thus the basic skeleton of the module looks like:
#include "pybind11/pybind11.h"
#define FORCE_IMPORT_ARRAY
#include "xgtensor-python/pyarray.hpp"
PYBIND11_PLUGIN(plugin_name)
{
xt::import_numpy();
pybind11::module m(//...
//...
return m.ptr();
}
Extension module with multiple files¶
If the extension module contain many source files that include xtensor-python
header files, the previous points are still
required. However, the source files that don’t contain the initializing code of the module can directly include xtensor-python
header files.
Using other extension modules¶
Including an header of xtensor-python
actually defines PY_ARRAY_UNIQUE_SYMBOL
to xtensor_python_ARRAY_API
. This might
be problematic if you import another library that defines its own PY_ARRAY_UNIQUE_SYMBOL
, or if you define yours. If so,
you can override the behavior of xtensor-python
by explicitly defining PY_ARRAY_UNIQUE_SYMBOL
prior to including any
stenxor-python
header:
// in every source file
#define PY_ARRAY_UNIQUE_SYMBOL my_uniqe_array_api
#include "xtensor-python/pyarray.hpp"