Re: Multiply inherit from classes with conflicting function names

From:

acehreli@yahoo.com

Newsgroups:

comp.lang.c++.moderated

Date:

24 May 2006 11:36:11 -0400

Message-ID:

<1148430339.758471.130390@y43g2000cwc.googlegroups.com>

Adam wrote:

I have an unfortunate case where a single class wants to derive from two
existing classes:

struct A { virtual long fun() = 0; };
struct B { virtual bool fun() = 0; };
struct Unfortunate : public A, public B { ??? };

Is it possible to fill in the ??? here with legal code?

You can introduce trivial intermediate classes to "rename" the
functions.

I need two different function bodies; A::fun and B::fun do unrelated
things.

More or less the same question with a twist: if A::fun and B::fun both
returned the same type, would it be possible to implement two functions
in C such that
C().A::fun()
and
C().B::fun()
would execute two different functions?

The intermediate classes would still work, but with a different syntax:

     C().A_fun();

Here is a complete test:

#include <iostream>

struct A { virtual long fun() = 0; };
struct B { virtual bool fun() = 0; };

struct A_impl : public A
{
    virtual long A_fun() = 0;
    virtual long fun()
    {
       return A_fun();
    }
};

struct B_impl : public B
{
    virtual bool B_fun() = 0;
    virtual bool fun()
    {
       return B_fun();
    }
};

struct Unfortunate : public A_impl, public B_impl
{
    virtual long A_fun()
    {
       std::cout << "long\n";
       return 0;
    }

    virtual bool B_fun()
    {
       std::cout << "bool\n";
       return false;
    }
};

int main()
{
    Unfortunate u;

    // Ambiguous to call fun()
    u.A_fun();
    u.B_fun();

    // No ambiguity through the base interfaces
    A & a = u;
    a.fun();
    B & b = u;
    b.fun();
}

Ali

      [ See http://www.gotw.ca/resources/clcm.htm for info about ]
      [ comp.lang.c++.moderated. First time posters: Do this! ]