C++ member function applied to object

Question

hi

I want to call member function by passing it as template parameter, without using boost is possible. Here is an example off what I tried to do,

class object { void method(); }

{
object object_instance;
...
apply<object:: method>();
...

template<class F>
void apply() { F(object_instance); } // want to call object_instance.F()
}

that does not work, so question is how do I go about binding object method to an object. Thanks

above is an example, not the real code. I have a bunch of functions differing only in name, but with many parameters, that I want to wrap around in operators.

Answer 1

As a member function isn't a type or integral value, you can't pass it as a template parameter. You could do what you seem to want by creating a struct which calls the member function, though having object_instance in scope in the template is rather smelly.

What are you actually trying to do?

Answer 2

Something like:

struct foo
{
    void bar(void) {}
};

template <typename R, typename C>
R apply(C& pObject, R (C::*pFunc)())
{
    return (pObject.*pFunc)();
}

int main(void)
{
    foo f;
    apply(f, &foo::bar);
}

this.

Answer 3

This example is for rvalue references in c++ox. Does not work on all compilers.

class Sample
{
public:
    void fun() { cout << "Sample::fun\n"; }
};

template<typename Function>
void FunCall( Function&& f)
{
    f();
}

void RvaluesDemo()
{
    FunCall([&]
    {
        Sample().fun();
    });
}

Answer 4

This is similar to your code, and will allow passing a member function as a template parameter:

class object { public: void method() {} };
object object_instance;

template<void (object::*F)()>
void apply() {
    (object_instance.*F)();
}

int main() {
    apply<&object::method>();
    return 0;
}