member function type deduction

// Deduction.h
#include<vector>


// Test Function
bool TestFun(int X)
{
	std::cout << "TestFun\n";
	return true;
};


// Test Component
struct ComponentB
{
	int Round(float X)
	{
		int x = (int)X;
		std::cout << "Round " << X << " = " << x << "\n";
		return x;
	}
};


// template type deduction from function arguments of function pointer
template<typename R, typename P1>
void Deduce( R(*pFunc)(P1) )
{
	// pFunc is a pointer to a function, but have we been able to deduce R and P1 ?
	R MyR;
	P1 MyParam1;

	MyR = pFunc(MyParam1);
	return;
};


// template type deduction from function arguments of member function pointer
template<typename R, typename T, typename P1>
void DeduceMFA( R(T::*pFunc)(P1) )
{
	// pFunc is a pointer to a Member function, but have we been able to deduce R, T and P1 ?
	R MyR;
	P1 MyParam1;
	T MyTarget;

	MyR = (MyTarget.*pFunc)(MyParam1);
	return;
};


// but we cannot use pFunc as a template argument for a templated type because it is a "local variable"!
template<typename R, typename T, typename P1>
void DeduceMFB( R(T::*pFunc)(P1) )
{
	// pFunc is a pointer to a Member function, but have we been able to deduce R, T and P1 ?
	R MyR;
	P1 MyParam1;
	T MyTarget;

	std::vector<pfunc> MyFuncts;	// Error pFunc is a local variable. Can't be used as template argument.

	MyR = (MyTarget.*pFunc)(MyParam1);
	return;
};


// so we implement it as a full template type
template<typename R, typename T, typename P1, typename R(T::*pFunc)(P1)>
void DeduceMFC( R(T::*pFunc)(P1) )
{
	// pFunc is a pointer to a Member function, but have we been able to deduce R, T and P1 AND  pFunc ?
	R MyR;
	P1 MyParam1;
	T MyTarget;

	MyR = (MyTarget.*pFunc)(MyParam1);
	return;
};


// code from main.cpp

// but then it cannot be deduced!!!

	Deduce( &TestFun );			// OK

	DeduceMFA( &ComponentB::Round );	// OK

	DeduceMFB( &ComponentB::Round );	// Error. 'pFunc' is not a valid template type argument for parameter '_Ty'

	DeduceMFC( &ComponentB::Round );	// Error. could not deduce template argument for 'pFunc'