Question

What can I use to dereference a template argument if it’s a pointer (or a smart pointer), or leave it as is if it’s not?

template<class T> void subf(const T& item)
{
    item.foo();
}

template<class T> void f(const T& item)
{
    subf(magic_dereference_function(item));
}

Anything in Boost is an option.

Answer 1

template <typename T>
T& maybe_deref(T& x) { return x; }

template <typename T>
T& maybe_deref(T* x) { return *x; }

You’ll have to add overloads for smart pointers individually. There’s no way to detected if a class is a “smart pointer”. You could detect the presence of operator->, but that doesn’t mean it’s a smart pointer.