I need to implement self contained compile-time function for checking type equality (function template without arguments bool eqTypes<T,S>()
).
self contained means not relying on library.
I'm not good in all this. That's what I tried, but it's not what I need.
template<typename T>
bool eq_types(T const&, T const&) {
return true;
}
template<typename T, typename U>
bool eq_types(T const&, U const&) {
return false;
}
It's quite simple. Just define a type trait and a helper function:
template<typename T, typename U>
struct is_same
{
static const bool value = false;
};
template<typename T>
struct is_same<T, T>
{
static const bool value = true;
};
template<typename T, typename U>
bool eqTypes() { return is_same<T, U>::value; }
Here is a live example.
In C++11, if you are allowed to use std::false_type
and std::true_type
, you would rewrite the above this way:
#include <type_traits>
template<typename T, typename U>
struct is_same : std::false_type { };
template<typename T>
struct is_same<T, T> : std::true_type { };
template<typename T, typename U>
constexpr bool eqTypes() { return is_same<T, U>::value; }
Notice, that the type trait std::is_same
, which does pretty much the same thing, is available as part of the Standard Library.