A little doubt about Inheritance

[DBarzo]

Hi,

I'm sorry for the "stupid" question...
In a my project I declare some interfaces to expose a c++ ABI from my library.
But maybe I forgot some rules.

Why this code does not work?

#include<iostream>

using namespace std;

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

class IBaseA : public IBase
{
public:
  virtual void foo_bar_A() = 0;
};



class BaseImpl : IBase
{
public:
  void foo(){cout << "BaseImpl::foo" << endl;};
};

class BaseAImpl : public IBaseA, public BaseImpl
{
public:
  void foo_bar_A(){cout << "BaseAImpl::foo_bar_A" << endl;};
};



int _tmain(int argc, _TCHAR* argv[])
{
  IBaseA* A = new BaseAImpl;  
  A->foo_bar_A();

  IBase* B = (IBase*)A;
  B->foo();

  delete A;

  return 0;
}

The compiler says that A is abstract.
Of course, not deriving IBaseA from IBase, make it works:

class IBaseA //: public IBase 

But in this way in the output I get:

BaseAImpl::foo_bar_A
BaseAImpl::foo_bar_A


Daniele.

[Bazzy]

BaseAImpl inherits IBase twice:

            IBaseA - IBase
          /
BaseAImpl 
          \ 
            BaseImpl - IBase

You can solve it adding virtual when inheriting IBase:
class IBaseA : virtual public IBase class BaseImpl : virtual IBase

[DBarzo]

Thanks a lot Bazzy!

Daniele.