Overloading by return type

I read few questions here on SO about this topic which seems yet confusing to me. I've just begun to learn C++ and I haven't studied templates yet or operator overloading and such.

Now is there a simple way to overload

class My {
public:
    int get(int);
    char get(int);
}

without templates or strange behavior? or should I just

class My {
public:
    int get_int(int);
    char get_char(int);
}

?


No there isn't. You can't overload methods based on return type.

Overload resolution takes into account the function signature. A function signature is made up of:

  • function name
  • cv-qualifiers
  • parameter types

And here's the quote:

1.3.11 signature

the information about a function that participates in overload resolution (13.3): its parameter-type-list (8.3.5) and, if the function is a class member, the cv-qualifiers (if any) on the function itself and the class in which the member function is declared. [...]

Options:

1) change the method name:

class My {
public:
    int getInt(int);
    char getChar(int);
};

2) out parameter:

class My {
public:
    void get(int, int&);
    void get(int, char&);
}

3) templates... overkill in this case.


It's possible, but I'm not sure that it's a technique I'd recommend for beginners. As in other cases, when you want the choice of functions to depend on how the return value is used, you use a proxy; first define functions like getChar and getInt, then a generic get() which returns a Proxy like this:

class Proxy
{
    My const* myOwner;
public:
    Proxy( My const* owner ) : myOwner( owner ) {}
    operator int() const
    {
        return myOwner->getInt();
    }
    operator char() const
    {
        return myOwner->getChar();
    }
};

Extend it to as many types as you need.


No, you can't overload by return type; only by parameter types, and const/volatile qualifiers.

One alternative would be to "return" using a reference argument:

void get(int, int&);
void get(int, char&);

although I would probably either use a template, or differently-named functions like your second example.