Multiple Inheritance Ambiguity

example in question:

Code:

class Base1
   {
public:
   void func();
   };

class Base2
   {
public:
   void func();
   };

class Derived : public Base1,
                public Base2
   {
   };

1- in the example above, how is ambiguity resolved
2- what if one or more of them were virtual
3- what other evils might multiple inheritance cause that I haven't thought of?

1. What ambiguity?
2. If the bases are virtual than you inherit the public implementations of them in the derived class.
3. Protected and Private iheritance is tricky because you iherit not just the public implimentations.

there are two functions of the same name. both classes are inherited. THAT ambiguity. I'll change the funcs to public. That shouldn't matter anyway.

Sorry, virtual means that you iherit the public interface, not the implementation. Non virtual is the implimentation. Think in terms of implementations and interfaces.

Than it probably has to be preceded by it's scope identifier, but I can't say for sure, being a Cer rather than a ligitimate C++er.

dude, you're not addressing the question. It's about multiple inheritance and the ambiguity introduced. I'm well aware of what virtual does normally.

Try using a scope identifier:

Derived Obj;
Obj.Base1::func(...);

The question is what if you don't specify which function. Which one does it call. That's where the term "ambiguity" comes in.

http://www.dictionary.com/search?q=ambiguity

Hopefully it provides a helpful error message, but with VC++6 there is no telling which one it will use.

but I'm sure there is a standard

There is a book called C++ FAQ. Maybe it's in there, or the C++ programming language. Why don't you try testing it.

I found the answer.

Code:

#include <iostream>
using namespace std;

class foo{
public:
	virtual void Sing(){cout << "Foo lalala" << endl;}
	
};
class bar{
public:
	virtual void Sing(){cout << "Bar lalala" << endl;}

};
class foobar: public foo,public bar{
public:
/*Can do what's below...but then why inherit?!..*/
//	void Sing(){foo::Sing();bar::Sing();}
};

int main(void) {
	foobar fb;
	foo* ptrfoo = &fb;
	bar* ptrbar = &fb;
	
//	fb.Sing(); //Will cause the ambiguity error!!
	fb.foo::Sing();
	fb.bar::Sing();

	ptrfoo->Sing();
	ptrbar->Sing();

	return 0;
}

I dont use much MI...but here's a few ideas...

You can implement a Sing() func in the derived class to call the other functions through the scope operator..not great unless you wish to call both....

You can also call the member function from an instance by specifying the base class

Also you can do it by calling from a casting up with a base pointer....

In other words, do exactly what I said above.