How can I prevent a variadic constructor from being preferred to the copy constructor?

Question

I have a template \'Foo\', which owns a T, and I\'d like it to have a variadic constructor that forwards its arguments to T\'s constructor:

template

        

Answer 1

Disable the constructor when the argument type is the same type as or derived from this:

template
struct is_this_or_derived : public std::false_type {};

template
struct is_this_or_derived
    : public std::is_base_of, std::decay_t >::type {};

template
using disable_for_this_and_derived 
      = std::enable_if_t::value>;

Use it as

template >
                                                //^^^^
                                                //this needs to be adjusted for each class
Foo(Args&&... args) : t(std::forward(args)...) {}