I have a concept as follows:
template<class T>
concept Reader = requires(T a)
{...};
I want to have a type trait which checks if a class conforms to the Reader concept – Something like is_reader<myclass>::value. How do I achieve this?
My attempts till now has been something like:
template<typename T>
struct is_reader : std::false_type;
template<Reader T>
struct is_reader : std::true_type;
This doesn’t compile due to re-declaration of template type.
I also tried:
template<typename T>
struct is_reader : std::false_type;
template<>
struct is_reader<Reader auto> : std::true_type;
While this compiles, it does not work.
How to make this work? Also why does my second try not work – What is it doing?
>Solution :
The correct way is
template<class T>
concept Reader = requires(T a) {...};
template<typename T>
struct is_reader : std::false_type {};
template<Reader T>
struct is_reader<T> : std::true_type {};