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c++templatesfriend

Friend template function

If I have

namespace A
{
        template<class T>
        inline void SomeFunc(T& archive, Object* object)
        {
            // ...
        }
}

and a non-template class

namespace B
{
    class Manager
    {
        // ...
        template <typename T, typename U> friend void A::SomeFunc(T& t, U* u);
    };
}

why doesn't class Manager recognize A::SomeFunc() as a friend?

What I'm trying to do: I'm gonna have a good number of these SomeFuncs, all taking different U classes (which derive from the same base), so I was looking for a clean way to do it without befriending tons of these functions.

Solution

  • The number of template arguments matter. You are befriending a template that takes two template arguments, but the real template has only one. They are different entities.

    Your friend declaration should be:

    template<class T>
friend void SomeFunc(T&, Object*);