Type deduction of reference_wrappers with Args

Question

I have a template function:

template<class... Args>
void foo(Args&&... args)
{
    boo<std::decay_t<Args>...>(std::forward<Args>(args)...);
}

Now what I want to do is to call foo function several times like this:

int value = 123;
const int& cr_value = value;
foo(value );
foo(std::cref(value ));

In first case I call boo<int> in second case boo<std::const_reference_wrapper<int>> is called. Is there way to "dereference" reference_wrapper automaticaly without explicit using of get function for every argument in pack? The reason for this is that I want to call boo<const int&> in second case, not boo<std::const_reference_wrapper<int>>

Answer 1

You might do something like:

template <typename T> struct unwrap {
    using type = T;
};
template <typename T> struct unwrap<std::reference_wrapper<T>> {
    using type = T&;
};

template <typename T> using unwrap_t = typename unwrap<T>::type;

template<class... Args>
void foo(Args&&... args)
{
    boo<unwrap_t<std::decay_t<Args>>...>(std::forward<Args>(args)...);
}

Demo.