Creating Instance of Python Extension Type in C

Question

I am writing a simple Vector implementation as a Python extension module in C that looks mostly like this:

typedef struct {
    PyObject_HEAD
    double x;
    double y;
} Vector;

static PyTypeObject Vector_Type = {
    ...
};

It is very simple to create instances of Vector while calling from Python, but I need to create a Vector instance in the same extension module. I looked in the documentation but I couldn't find a clear answer. What's the best way to do this?

Answer 1

Simplest is to call the type object you've created, e.g. with PyObject_CallFunction -- don't let the name fool you, it lets you call any callable, not just a function.

If you don't have a reference to your type object conveniently available as a static global to your C module, you can retrieve it in various ways, of course (e.g., from your module object with a PyObject_GetAttrString). But sticking that PyObject* into a static module-level C variable is probably simplest and most convenient.