C++

Reference

<type_traits>

class template
<type_traits>

std::is_move_assignable

template <class T> struct is_move_assignable;
Is move assignable

Trait class that identifies whether T is a move assignable type.

A move assignable type is a type that can be assigned an rvalue reference of the same type. This includes scalar types and move assignable classes.

A move assignable class is a class that either has its move assignment operator defined (either the implicitly provided one or a custom defined one), or a copy assignment that is called for rvalue references (these are always called unless the class has a deleted move assignment operator).

The is_move_assignable class inherits from integral_constant as being either true_type or false_type, depending on whether T is move assignable.

Template parameters

T
A complete type, or void (possible cv-qualified), or an array of unknown bound.

Member types

Inherited from integral_constant:
member typedefinition
value_typebool
typeeither true_type or false_type

Member constants

Inherited from integral_constant:
member constantdefinition
valueeither true or false

Member functions

Inherited from integral_constant:
operator bool
Returns value (public member function)

Example

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// is_move_assignable example
#include <iostream>
#include <type_traits>

struct A { };
struct B { B& operator= (B&&) = delete; };

int main() {
  std::cout << std::boolalpha;
  std::cout << "is_move_assignable:" << std::endl;
  std::cout << "int: " << std::is_move_assignable<int>::value << std::endl;
  std::cout << "A: " << std::is_move_assignable<A>::value << std::endl;
  std::cout << "B: " << std::is_move_assignable<B>::value << std::endl;
  return 0;
}

Output:
is_move_assignable:
int: true
A: true
B: false


See also

is_assignable
Is assignable (class template)
is_copy_assignable
Is copy assignable (class template)
is_move_constructible
Is move constructible (class template)
is_trivially_move_assignable
Is trivially move assignable (class template)
is_nothrow_move_assignable
Is move assignable throwing no exception (class template)