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c++templatestypename

type template for derived classes

template <typename ElementType>
class AList{};
class A{};
class B : public A{};
class C : public A{};
class D : public A{};
template <typename TypeE>
class E{};
(...)
       AList< E<A> > ListofEwithBCandDasTypE;

However the displayed code only makes a list of E with A as template argument. How can I solve that?

Solution

  • With C++98 (I'm not comfortable with C++11).

    You need polymorphism and manage pointers instead of objects directly. See this example :

    class A
{
  public:
    virtual ~A() {}
};
class B : public A
{
  public:
    virtual ~B() {}
};
class C : public A
{
  public:
    virtual ~C() {}
};
template <typename T>
class AList
{
  public:
    add(T* x);
    // ...
};
template <typename T>
class E
{
  public:
    E(A* ptr) { /*...*/ }
    // ...
};
AList< E<A*> > list;
list.add(E(new B));
list.add(E(new C));

    Don't forget to manage your memory !