Abstract base class puzzle
- by 0x80
In my class design I ran into the following problem:
class MyData
{
int foo;
};
class AbstraktA
{
public:
virtual void A() = 0;
};
class AbstraktB : public AbstraktA
{
public:
virtual void B() = 0;
};
template<class T>
class ImplA : public AbstraktA
{
public:
void A(){ cout << "ImplA A()"; }
};
class ImplB : public ImplA<MyData>, public AbstraktB
{
public:
void B(){ cout << "ImplB B()"; }
};
void TestAbstrakt()
{
AbstraktB *b = (AbstraktB *) new ImplB;
b->A();
b->B();
};
The problem with the code above is that the compiler will complain that AbstraktA::A() is not defined.
Interface A is shared by multiple objects. But the implementation of A is dependent on the template argument. Interface B is the seen by the outside world, and needs to be abstrakt.
The reason I would like this is that it would allow me to define object C like this:
Define the interface C inheriting from abstrakt A.
Define the implementation of C using a different datatype for template A.
I hope I'm clear. Is there any way to do this, or do I need to rethink my design?
