#include <iostream>
#include <type_traits>
 
struct A    { void reset() { std::cout << "reset A" << std::endl; } };
struct B    { void reset() { std::cout << "reset B" << std::endl; } };
 
struct X :public A{};
 
template <typename T, typename R, typename BT>
R call_if_possible_impl(T & obj, R(BT::*mf)(), std::false_type){}
 
template <typename T, typename R, typename BT>
R call_if_possible_impl(T & obj, R(BT::*mf)(), std::true_type)
{
	return (obj.*mf)();
}
 
template <typename T, typename R, typename BT>
R call_if_possible(T & obj, R(BT::*mf)())
{
	return call_if_possible_impl(obj, mf, typename std::is_base_of<BT, T>::type());
}
 
int main()
{
	X x;
 
	call_if_possible(x, &A::reset);
	call_if_possible(x, &B::reset);
}

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