I have a manager class, allows the user to create components via a public interface. The use can specify the component type, and pass in the construction arguments to the manager class, which will create the component object.

However I am trying to restrict the user from creating certain component type, so their specialisations are private. But because the component type is not a function argument, I can’t figure out how to specialise it.

I am getting the error non-class, non-variable partial specialization 'add_component<transform, Args ...>' is not allowed.

class ecs_manager {
public:
    // Allow users to add components via a public interface.
    template<typename T, typename... Args>
    T *add_component(ecs_id_t _entity, Args &&... _args) {
        return get_or_create_pool<T>()->add_component(_entity, std::forward<Args>(_args)...);
    }

private:
    // But there are certain components that should only be added by the manager.
    // So we put the specialisations in private.
    template<typename T, typename... Args>
    transform* add_component<transform, ...Args>(ecs_id_t _entity, Args &&... _args) {
        return get_or_create_pool<transform>()->add_component(_entity, std::forward<Args>(_args)...);
    }
};