1[#boxed_value] 2[section Boxed value] 3 4A ['boxed value] is a type representing a constant value. It has a public static 5`const` or `constexpr` member called `value`. The class represents that value as 6a type, so it can be manipulated by [link metafunction template metafunction]s. 7It has to be a [link metaprogramming_value template metaprogramming value]. 8 9For example the following `struct` represents the `true` value of type `bool`: 10 11 struct true_type 12 { 13 static constexpr bool value = true; 14 using type = true_type; 15 }; 16 17The `value` member is the wrapped value. `true_type::type` is an alias of 18`true_type` which makes it a template metaprogramming value. 19 20[endsect] 21 22