Implementing multiple interfaces in c++

Question

I have the interface hierarchy as follows:

class A
{
public:
 void foo() = 0;
};

class B: public A
{
public:
void testB() = 0;
};

class C: public A
{
publi         


        

Answer 1

While I'd normally think twice before suggesting multiple inheritance. If your needs really aren't more complicated than you said, then just inherit both interface and implementation virtually.

class A
{
public:
  void foo() = 0;
};

class B: virtual public A
{
public:
  void testB() = 0;
};

class C: virtual public A
{
public:
  void testC() = 0;
};

class AImpl : virtual public A
{
 ...
}

class BImpl : virtual public B, virtual public AImpl
{
 ...
}

The virtual inheritance will make sure there is only one sub-object A shared between B and AImpl. So you should be in the clear. The object size will increase, however. So if that's an issue, rethink your design.