Wrap C struct with array member for access in python: SWIG? cython? ctypes?

Question

I want to access a C function that returns a struct containing double arrays (where the lengths of these arrays is given by other int members of the struct) from python. The dec

Answer 1

Check out SWIG's typemaps. They let you write your own code for handling specific types, specific instances (type+name) or even groups of arguments. I haven't done it for structures, but to specially handle a case where the C function takes an array and its size:

%typemap(in) (int argc, Descriptor* argv) {
    /* Check if is a list */
    if (PyList_Check($input)) {
        int size = PyList_Size($input);
        $1 = size;
        ...
        $2 = ...;
    }
}

That will take the pair of arguments int argc, Descriptor* argv (since the names are provided they have to match as well) and pass you the PyObject used and you write whatever C code you need to do the conversion. You could do a typemap for double *dn that would use the NumPy C API to do the conversion.