Cython PXD

The use of PXD files is very similar to that of header files in C/C++. When writing bindings to any C/C++ code, it is a good practice to declare all C/C++ interfaces within a .pxd file. This stands for Python External Declarations, at least it does in my mind. So, when we add blocks such as this:

cdef extern from "AddFunction.h":
    cdef int AddFunction(int, int)

We can instead put this directly into a bindings.pxd file and import this at any time inside any .pyx file:

cimport bindings

Notice the distinction between cimport for the .pxd files and a simple import for all normal Python imports.

Tip

Cython's input filenames cannot handle dashes (-) in their filenames. It's best to try and use CamelCase, since you can't use cimport my-import in Python.