Is there an equivalent of Python's __rmul__ in C++?

Question

Python 3 allows overloading of *.

For example,

a*b

Allows a to define the result by providing a __mul__ method.

If however that method returns NotImplemented, the __rmul__ method on b is called (if it exists) to give the result. This is documented here.

One advantage of this is that I can make on object b that operates on a without knowing the class of a.

Is there an equivalent to __rmul__ in C++, or a way of achieving the same or a similar thing?

Answer 1

Correct me if I'm wrong, but according to my understanding, you need to overload an operator for 2 different classes.

You can do something like this as under:

#include <iostream>

class A
{
public:
    int integer;
};

class B
{
public:
    double decimal;
};

//A * B
double operator*(A a, B b)
{
    return a.integer * b.decimal;
}

int main() 
{
    A a{12}; B b{2};
    double c = a * b;

    std::cout << c;
}

In the above example, I've overloaded operator* to multiply 2 objects of type A and B. But it only works for a * b, not b * a. So you can do something like this:

//B * A
double operator*(B b, A a)
{
    return a.integer * b.decimal;
}