gistfile1.cpp

#include <functional>
#include <iostream>
template<typename T>
class MaybePtr{
	T* ptr;
public:
	MaybePtr(T* p) : ptr(p) {}

	template <typename F,typename R = std::result_of<F(T*)>::type>
	R Get(F access,R default_value){
		if (ptr != nullptr)
			return access(ptr);
		else
			return default_value;

	}
	void Access(std::function<void(T*)> access){
		if (ptr != nullptr)
			access(ptr);
	}
};
int main(){
	int * iptr = new int;
	*iptr = 10;
	auto m = MaybePtr<int>(iptr);

	auto addOne = [](int* i) -> int {
		return *i + 1;
	};
	auto setTo42 = [](int* i) {
		*i = 42;
	};
	m.Access(setTo42);
	int r = m.Get(addOne, 0);

	std::cout << r;
	int i;
	std::cin >> i;
}