I have some troubles with the application of polymorphism in this example. This question is similar to my last question
C++, virtual inheritance, strange abstract class + clone problem
There are 3 abstract classes:
class A
{
public:
virtual A * copy () const = 0;
virtual ~A() = 0;
};
A::~A(){}
class B
{
public:
virtual B * copy () const = 0;
virtual ~B() = 0;
};
B::~B(){}
class C: virtual public A , public B
{
public:
virtual C * copy () const = 0;
virtual ~C() = 0;
};
C::~C(){}
and two inherited classes using the virtual inheritance
class D: virtual public A
{
public:
virtual D * copy () const {return new D (*this);}
virtual ~D() {}
};
class E: virtual public D , public C
{
public:
virtual E * copy () const {return new E (*this);}
virtual ~E() {}
}; //Error C2250: 'E' : ambiguous inheritance of 'D *A::copy(void) const
The above mentioned error occurs only using MSVS 2010 compiler, g++ compiles this code OK.
Class diagram (simplified)
.......... A .... B.....
........../.\..../......
........./...\../.......
......../.....\/........
.......D...... C........
........\...../.........
.........\.../..........
..........\./...........
...........E............
Last discussion we close with the result: remove the declaration of the copy() method from class C.
class C: virtual public A , public B
{
public:
//virtual C * copy () const = 0; //remove declaration
virtual ~C() = 0;
};
C::~C(){}
My sample code using polymorphism needs to create vector of pointers to C. After removing some element I want to create its copy... I NEED a declaration of copy() in class C, so removal of the declaration is insufficient and it does not solve the problem.
int main(int argc, char* argv[])
{
std::vector <C*> items;
items.push_back(new E());
items.push_back(new E());
items[0]->copy();
return 0;
}
Could you help me, please how to correct the code to be translatable using VS 2010?
