can member operators be virutal? does it make sense?

[puzzlecracker]

I have never seen this in practice and interested in its pros, or ever
existential (another words, standardized) possibility?


Thanks,

Sasha

 

[Alan Woodland]

I have never seen this in practice and interested in its pros, or ever
existential (another words, standardized) possibility?

As far as I know it's standardised - this works exactly as you'd expect:

#include <iostream>

class Foo {
public:
virtual void operator()(const int& a) { std::cout << "Foo" << std::endl; }
};

class Bar : public Foo {
public:
virtual void operator()(const int& a) { std::cout << "Bar" << std::endl; }
};

int main() {
Bar& b = *new Bar();
Foo& f = *new Foo();
Foo& fb = b;

b(10);
f(5);
fb(5);

return 0;
}

Alan

 

[Victor Bazarov]

I have never seen this in practice and interested in its pros, or ever
existential (another words, standardized) possibility?

I see nothing special in a member operator versus any other non-static
member function. Yes, absolutely, they can be virtual and it does make
sense to make them virtual if you need polymorphic behaviour.

Operators are nothing but syntactic sugar. Instead of, say, a function

...
virtual void doSomethingWith(int);
...

you could write

...
virtual void operator+(int);
...

.. And later, instead of writing

myobjectRef.doSomethingWith(42);

you would write

myojbectRef + 42;

Now, whether this makes sense is entirely problem-specific and cannot
be judged without any regard to what the purpose of the code is.

V