std::readable_traits
From cppreference.com
Defined in header <iterator>
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template< class I > struct readable_traits { }; |
(1) | (since C++20) |
template< class T > struct readable_traits<T*>; |
(2) | (since C++20) |
template< class I > requires std::is_array_v<I> |
(3) | (since C++20) |
template< class T > struct readable_traits<const T> : value_type<T> { }; |
(4) | (since C++20) |
template <class T> requires requires { typename T::value_type; } |
(5) | (since C++20) |
template <class T> requires requires { typename T::element_type; } |
(6) | (since C++20) |
Computes the associated value type of the type I
, if any. Users may specialize readable_traits
for a program-defined type.
1) Primary template is an empty struct.
2) Specialization for pointers. If
T
is an object type, provides a member type value_type
equal to std::remove_cv_t<T>. Otherwise, there is no member value_type
.3) Specialization for array types. Provides a member type
value_type
equal to std::remove_cv_t<std::remove_extent_t<I>>.4) Specialization for const-qualified types.
5) Specialization for types that define a public and accessible member type
value_type
. If T::value_type
is an object type, provides a member type value_type
equal to std::remove_cv_t<typename T::value_type>. Otherwise, there is no member value_type
.6) Specialization for types that define a public and accessible member type
element_type
(e.g., std::shared_ptr). If T::element_type
is an object type, provides a member type value_type
equal to std::remove_cv_t<typename T::element_type>. Otherwise, there is no member value_type
.Notes
If a type contains both a value_type
member and a element_type
member, then the specializations (5) and (6) are ambiguous.
value_type
is intended for use with Readable
types such as iterators. It is not intended for use with ranges.
Example
This section is incomplete Reason: no example |
See also
specifies that a type is readable by applying operator * (concept) | |
computes the associate types of an iterator (alias template) | |
provides uniform interface to the properties of an iterator (class template) |