Force Template to be Subclass

[o1vk4iN6]

Is there any way to for a template argument to be inherited from a certain class.

template<class T>
class A {
   T t;

public:
   void foo(){ t.foo(); }
};

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

class C : public B {
public:   
   void foo();
};

class D {
   
};

A<C> ac; // ok

A<D> ad; // error

So I want the "T" in class "A" to be inherited from "B" so that it can use the "foo" function. There'd be an error since there's no foo function in class D but the message is kind of cryptic.

[ne555]

There is a big difference, but

class A{
  B *t;
};

error: 'class D' has no member named 'foo'

¿cryptic? However that error only appears if you try to use the foo method on the ad object.

[Peter87]

Not possible

[o1vk4iN6]

I could do some sort of assert in the constructor yah? Wouldn't help with any error messages unless it manages to compile somehow.

A()
{
   assert( dynamic_cast<B*>(&t) != NULL );
} 

I need to pass it as a template though since it needs to be able to construct/destruct the class. Otherwise ne555 I would do that. Thanks for the help.

[ne555]

since it needs to be able to construct/destruct the class

¿?
I don't understand what you mean.
¿how is that you can do that with templates?