The public keyword

This is a very powerful keyword in Cython. It allows any cdef declaration with the public modifier to output a respective C/C++ header with the relative declaration accessible from C/C++. For example, we can declare:

cdef public struct CythonStruct:
    size_t number_of_elements;
    char ** elements;

Once the compiler handles this, you will have an output of cython_input.h:

 struct CythonStruct {
    size_t number_of_elements;
    char ** elements;
};

The main caveat, if you're going to call the Python public declarations directly from C, is that, if your link model is fully embedded and linked against libpython.so, you need to use some boilerplate code to initialize Python correctly:

#include <Python.h>

int main(int argc, char **argv) {
    Py_Initialize ();
    // code in here
    Py_Finalize ();
    return 0;
}

And before calling anything with the function, you need to initialize the Python module example if you have a cythonfile.pyx file, and compile it with the...