std::is_copy_assignable, std::is_trivially_copy_assignable, std::is_nothrow_copy_assignable
cppreference.com
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template< class T > struct is_copy_assignable; |
(1) | ( C++11) |
template< class T > struct is_trivially_copy_assignable; |
(2) | ( C++11) |
template< class T > struct is_nothrow_copy_assignable; |
(3) | ( C++11) |
1)
T , (.., , cv- void cv- ), - value, false. - value, std::is_assignable<T&, const T&>::value.2) , (1),
std::is_trivially_assignable<T&, const T&>3) , (1),
std::is_nothrow_assignable<T&, const T&>T , (, cv-) void . .
, , , .
, , .
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template< class T > inline constexpr bool is_copy_assignable_v = is_copy_assignable<T>::value; |
( C++17) | |
template< class T > inline constexpr bool is_trivially_copy_assignable_v = is_trivially_copy_assignable<T>::value; |
( C++17) | |
template< class T > inline constexpr bool is_nothrow_copy_assignable_v = is_nothrow_copy_assignable<T>::value; |
( C++17) | |
std::integral_constant
value [static] |
true, T , false (public static -) |
-
operator bool |
bool, value (public -) |
operator() (C++14) |
value (public -) |
value_type
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bool
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type
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std::integral_constant<bool, value>
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template< class T>
struct is_copy_assignable
: std::is_assignable< typename std::add_lvalue_reference<T>::type,
typename std::add_lvalue_reference<const T>::type> {};
template< class T>
struct is_trivially_copy_assignable
: std::is_trivially_assignable< typename std::add_lvalue_reference<T>::type,
typename std::add_lvalue_reference<const T>::type> {};
template< class T>
struct is_nothrow_copy_assignable
: std::is_nothrow_assignable< typename std::add_lvalue_reference<T>::type,
typename std::add_lvalue_reference<const T>::type> {};
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std::is_copy_assignable , CopyAssignable, ( CopyAssignable T) , . , T MoveAssignable, CopyAssignable.
#include <iostream>
#include <utility>
#include <type_traits>
struct Foo { int n; };
int main() {
std::cout << std::boolalpha
<< "Foo ? "
<< std::is_trivially_copy_assignable<Foo>::value << '\n'
<< "int[2] ? "
<< std::is_copy_assignable<int[2]>::value << '\n'
<< "int ? "
<< std::is_nothrow_copy_assignable<int>::value << '\n';
}
:
Foo ? true
int[2] ? false
int ? true
(C++11)(C++11)(C++11) |
, ( ) |
(C++11)(C++11)(C++11) |
, ( ) |