Question

I try to have a partially specialized template class inheriting from another template class. I’m not sure how to to that. Here is my code:

template < typename T>
struct SmallContainer
{
    typedef vector<T> type;
};

template<typename CONTAINER, typename T>
class AnotherClass : public CONTAINER<SmallContainer<T>::type>
{ // ..... };

and gcc keeps saying
expected template-name before ‘<’ token
expected ‘{’ before ‘<’ token
expected unqualified-id before ‘<’ token

The idea of my object is to have AnotherClass be a generic container of vector of any other type I want.

I tried to do template< template CONTAINER, typename T> etc… without any success.
Any idea ?
Thanks…

Answer 1

This would work for a container of just one template argument:

template< template< typename > class Container, typename T >
class AnotherClass
  : public Container< typename SmallContainer< T >::type >
{};

This, however, won’t work for any of the standard containers as they have extra template arguments (like allocator).

Note that typename is needed before SmallContainer< T >::type or otherwise the compiler will assume it refers to a value.