Functionality of void operator()()

Question

I am confused about the functionality of void operator()().

Could you tell me about that, for instance:

class background_task
{
public:

            


        

Answer 1

You can overload the () operator to call your object as if it was a function:

class A {
public:
    void operator()(int x, int y) {
        // Do something
    }
};

A x;
x(5, 3); // at this point operator () gets called

So the first parentheses are always empty: this is the name of the function: operator(), the second parentheses might have parameters (as in my example), but they don't have to (as in your example).

So to call this operator in your particular case you would do something like task().