Namespaces
Variants
Views
Actions

std::is_move_assignable, std::is_trivially_move_assignable, std::is_nothrow_move_assignable

From cppreference.com
< cpp‎ | types
Revision as of 17:13, 2 November 2012 by P12bot (Talk | contribs)

 
 
 
Type support
Basic types
Fundamental types
Fixed width integer types (C++11)
Numeric limits
C numeric limits interface
Runtime type information
Type traits
Primary type categories
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
Type properties
(C++11)
(C++11)
(C++11)
(C++14)
Supported operations
is_move_assignableis_trivially_move_assignableis_nothrow_move_assignable
(C++11)(C++11)(C++11)
Relationships and property queries
(C++11)
(C++11)
(C++11)
(C++11)
Type modifications
(C++11)(C++11)(C++11)
Type transformations
(C++11)
(C++11)
(C++11)
Type trait constants
 

Template:ddcl list begin <tr class="t-dsc-header">

<td>
Defined in header <type_traits>
</td>

<td></td> <td></td> <tr class="t-dcl ">

<td >
template< class T >
struct is_move_assignable;
</td>

<td > (1) </td> <td > (since C++11) </td> </tr> <tr class="t-dcl ">

<td >
template< class T >
struct is_trivially_move_assignable;
</td>

<td > (2) </td> <td > (since C++11) </td> </tr> <tr class="t-dcl ">

<td >
template< class T >
struct is_nothrow_move_assignable;
</td>

<td > (3) </td> <td > (since C++11) </td> </tr> Template:ddcl list end

1) Checks whether a type is MoveAssignable, i.e. has an accessible explicit or implicit move assignment operator. If the requirement is met, a member constant value equal true is provided, otherwise value is false.

2) same as 1), but evaluation of the move-assignment expression will not call any operation that is not trivial.

3) same as 1), but the evaluation of the move-assignment expression will not call any operation that is not noexcept.

Contents

Inherited from std::integral_constant

Member constants

value
[static]
true if T is move-assignable, false otherwise
(public static member constant)

Member functions

operator bool
converts the object to bool, returns value
(public member function)

Member types

Type Definition
value_type bool
type std::integral_constant<bool, value>

Possible implementation

template< class T>
struct is_move_assignable
    : std::is_assignable< typename std::add_lvalue_reference<T>::type,
                          typename std::add_rvalue_reference<T>::type> {};
 
template< class T>
struct is_trivially_move_assignable
    : std::is_trivially_assignable< typename std::add_lvalue_reference<T>::type,
                                    typename std::add_rvalue_reference<T>::type> {};
 
template< class T>
struct is_nothrow_move_assignable
    : std::is_nothrow_assignable< typename std::add_lvalue_reference<T>::type,
                                  typename std::add_rvalue_reference<T>::type> {};

Example

#include <iostream>
#include <string>
#include <type_traits>
struct Foo { int n; };
int main() {
    std::cout << std::boolalpha
              << "std::string is nothrow move-assignable? "
              << std::is_nothrow_move_assignable<std::string>::value << '\n'
              << "int[2] is move-assignable? "
              << std::is_move_assignable<int[2]>::value << '\n'
              << "Foo is trivally move-assignable? "
              << std::is_trivially_move_assignable<Foo>::value << '\n';
}

Output:

std::string is nothrow move-assignable? true
int[2] is move-assignable? false
Foo is trivially move-assignable? true

See also

checks if a type has a assignment operator for a specific argument
(class template) [edit]
checks if a type has a copy assignment operator
(class template) [edit]