How can I use std::decay when partially specializing a type trait?

Question

I made these type traits to determine if the type is a dynamic container, but recently ran into confusion when a reference to a vector didn't return true.

template<typename T>
struct is_dynamic_container
{
    static const bool value = false;
};

template<typename T , typename Alloc>
struct is_dynamic_container<std::vector<T , Alloc>>
{
    static const bool value = true;
};

I think I need to use std::decay, but I'm having trouble figuring out if it can be done like this rather than at the call site.

template<typename T , typename Alloc>
struct is_dynamic_container<std::decay<std::vector<T , Alloc>>::type>
{
    static const bool value = true;
};

^^This doesn't work.

I just want to be able to write is_dynamic_container<std::vector<int>&> and not is_dynamic_container<std::decay<std::vector<int>&>::type>. Is that possible?

Answer 1

template<class T>
using is_dynamic_container_with_decay = is_dynamic_container<std::decay_t<T>>;