made variant more practical

include/gp/variant.hpp

@@ -18,7 +18,7 @@ namespace gp{
 	class fixed_variant{
 		std::size_t index = std::numeric_limits<std::size_t>::max();
 		char buffer[max_size<T...>()];
-		gp::function<void(void*)p">, dummy_allocator> dtor = [](void*){};
+		gp::function<void(void*)> dtor = [](void*){};
 		static_assert(all_of_fixed_size<T...>::value, "not fixed");
 	public:
 		template<typename U, typename std::enable_if<list_contains_class<U,T...>::value,int>::type>
@@ -26,7 +26,7 @@ namespace gp{
 		: index{r_index_of<U, T...>::value}
 		{
 			new(buffer) U(value);
-			dtor = gp::function<void(void*)p">, dummy_allocator>([](void* thing){((U*)thing)->~U();});
+			dtor = gp::function<void(void*)>([](void* thing){((U*)thing)->~U();});
 		}
 
 		template<typename U, typename std::enable_if<list_contains_class<U,T...>::value,int>::type>
@@ -34,10 +34,17 @@ namespace gp{
 		: index{r_index_of<U, T...>::value}
 		{
 			new(buffer) U(std::move(value));
-			dtor = gp::function<void(void*)p">, dummy_allocator>([](void* thing){((U*)thing)->~U();});
+			dtor = gp::function<void(void*)>([](void* thing){((U*)thing)->~U();});
 		}
 
+		template<typename U>
+		constexpr size_t alt() const {
+			return r_index_of<U, T...>::value;
+		}
 
+		size_t type() const {
+			return index;
+		}
 
 		template<typename U, typename std::enable_if<list_contains_class<U,T...>::value,int>::type>
 		void operator=(U& value)