Cython wrapping operator<< from multiple namespaces

Question

How can I wrap the operator >> overload in Cython?

//LIB.h
namespace LIB
{
    class Point
    {
        friend std::istream &operator >> (std::istream &in, Point &pt)
        bool operator == (const Point &pos) const
        ...
    }
}

There is already a namespace declared namespace "LIB":, so how do I deal with the std:: namespace?

#LIB.pxd
cdef extern from "LIB.h" namespace "LIB":
    cdef cppclass Point:
        #friend std::istream &operator >> (std::istream &in, Point &pt)
        bint operator == (const Point &pos) const
        ...

Here it explains that multiple cdef extern blocks are possible, but I don't see how that will work since I cannot redefine the class.

Answer 1

I think the easiest solution is to pretend to Cython that operator<< is a method of std::istream forgetting about the friend stuff. The C++ compiler will then sort out the pieces. So here is what seems to be a working solution (it compiles but I didn't went all the way to test it):

Here is my LIB.h wrapped file:

#include <iostream>
namespace LIB {
    class Point {
        friend std::istream &operator << (std::istream &in, Point);
    };
}

And the Cython wrapper should be as follows:

cdef extern from "LIB.h" namespace "LIB":
    cdef cppclass Point:
        pass

cdef extern from "<iostream>" namespace "std":
    cdef cppclass istream:
        istream &operator << (Point)

    istream cin

Then the following file is accepted by the compiler:

cimport lib

def foo():
    cdef lib.Point bla

    lib.cin << bla

FYI, I compiled with:

cython --cplus bla.pyx                  
g++ `python-config --cflags` bla.cpp -c