How to overload "@" operator in python?

Question

How can we overload the @ operator?

I know that we can overload the +, *, etc. operators by implementing the __add__, __mul__, etc. methods, but what is the equivalent for @?

Answer 1

The @ operator was introduced in python 3.5 to facilitate matrix multiplication (see PEP 465 - A dedicated infix operator for matrix multiplication).

As indicated in the PEP definition, the @ operator can be overloaded using __matmul__ as it was initially introduced to perform matrix multiplication.

class foo:
    def __init__(self, A):
        self.A = A

    def __matmul___(self, B):
        # some operations on self.A and B
        return ...

Like any other operator, you can overload its in place version @= using __imatmul__ as well as its reflected version with __rmatmul__.