call Cython function from C++

Question

I have a C++ library that has a Python wrapper (written with SWIG). This library allows executing small user-defined code (a callback), such as element-wise operations on a

Answer 1

The trick with cython is in using the keyword public

cdef public double cython_function( double value, double value2 ):
    return value + value2

Then the command cythonize along with will create header that you can include. Alternatively, you can create the header yourself:

#ifdef __cplusplus {
extern "C"
#endif

double cython_function( double value, double value2 );

#ifdef __cplusplus
}
#endif

Update:

Then with a little overlay from Python you can use ctypes's callback mechanism

func_type = CFUNCTYPE(c_double, c_double, c_double)

your_library.set_callback_function ( func_type(user_modules.cython_function) )