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Overloading a call function for a derived class parameter with a base class parameter

I'm not sure if my title is detailed enough, but I don't know how best to put it in words. Basically, I want to have, for example, these classes:

class A {};
class B : public A{};
class C : public A{};

these two functions:

void cry(B* param){ cout << "Wee"; };
void cry(C* param){ cout << "Woo"; };

and this piece of code:

int main()
{
    A* weener = new B();
    A* wooner = new C();
    cry(weener);
    cry(wooner);
}

and I expect this output:

wee
woo

But that, in my case, it won't even compile. Is it possible? If so, what is the correct approach?
PS: cry function must be outside of classes

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2 answers


A simple workaround could be to define a single function cry

that chooses its behavior based on the dynamic type of its parameter:

void cry(A* param)
{
    if( dynamic_cast<B*>(param) ) //do something
        ;
    else if( dynamic_cast<C*>(param) ) // do something else
        ;
}


Obviusly, this is allowed at runtime and comes with (often negligible) runtime costs.

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You have to overlay these objects:

cry(static_cast<B*>(weener));
cry(static_cast<C*>(wooner));


Otherwise, the compiler will look for a function cry

that takes A*

an argument (because weener

and wooner

have been declared as type A*

really).

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