Question

I have

template <void (*T)(Entity *), typename Caller>
class Updater 
{
public:
    Updater(Caller c):m_caller(c){}
    void process(Entity * e)
    {
        (m_caller->*T)(e);              //Is this right?
    }
private:
    Caller m_caller;
};

I understand I can instantiate it like

Foo f;
Updater<&Foo::Bar> updater(&f);

assuming that Foo has

void Foo::Bar(Entity *e);

but what if it has desired method tempated? Like this

template <typename T>
void Bar(T t);

how shoult I instanciate it? Like this:?

Foo f;
Updater<&Foo::Bar<Entity *>> updater(&f);

When I do this in my real code, I get

invalid template argument for ..., expected compile-time constant expression

So 2 questions:

1, is (m_caller->*T)(e); correct? If it is not, how shout i call it?

2, how can I instantiate it?

Answer 1

template <typename Caller, void (Caller::*Func)(Entity *)>
class Updater 
{
public:
    Updater(Caller *c):m_caller(c){}
    void process(Entity * e)
    {
        (m_caller->*Func)(e); // use pointer to member operator ->*
    }
private:
    Caller *m_caller;
};

// call like this
Foo f;
Updater<Foo, &Foo::Bar> updater(&f);