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std::indirect<T, Allocator>:: operator=

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C++
Memory management library
( exposition only* )
Allocators
Uninitialized memory algorithms
Constrained uninitialized memory algorithms
Memory resources
Uninitialized storage (until C++20)
( until C++20* )
( until C++20* )
( until C++20* )

Garbage collector support (until C++23)
(C++11) (until C++23)
(C++11) (until C++23)
(C++11) (until C++23)
(C++11) (until C++23)
(C++11) (until C++23)
(C++11) (until C++23)
std::indirect
constexpr indirect & operator = ( const indirect & other ) ;
(1) (since C++26)
constexpr indirect & operator = ( indirect && other ) noexcept ( /* see below */ ) ;
(2) (since C++26)
template < class U = T >
constexpr indirect & operator = ( U && value ) ;
(3) (since C++26)

Replaces contents of * this with value or the contents of other .

Let traits be std:: allocator_traits < Allocator > :

1) If std:: addressof ( other ) == this is true , does nothing. Otherwise, let need_update be traits :: propagate_on_container_copy_assignment :: value :
  • If other is valueless, * this becomes valueless and the object owned by * this (if any) is destroyed using traits :: destroy and then the storage is deallocated.
  • Otherwise, if alloc == other. alloc is true and * this is not valueless, equivalent to ** this = * other .
  • Otherwise:
  1. Constructs a new owned object in * this using traits :: construct with * other as the argument, using the allocator update_alloc ? other. alloc : alloc .
  2. The previously owned object in * this (if any) is destroyed using traits :: destroy and then the storage is deallocated.
  3. p points to the new owned object.
After updating the object owned by * this , if need_update is true , alloc is replaced with a copy of other. alloc .
If std:: is_copy_assignable_v < T > && std:: is_copy_constructible_v < T > is false , the program is ill-formed.
2) If std:: addressof ( other ) == this is true , does nothing. Otherwise, let need_update be traits :: propagate_on_container_move_assignment :: value :
  • If other is valueless, * this becomes valueless and the object owned by * this (if any) is destroyed using traits :: destroy and then the storage is deallocated.
  • Otherwise, if alloc == other. alloc is true , swaps the owned objects in * this and other ; the owned object in other (if any) is then destroyed using traits :: destroy and then the storage is deallocated.
  • Otherwise:
  1. Constructs a new owned object in * this using traits :: construct with std :: move ( * other ) as the argument, using the allocator update_alloc ? other. alloc : alloc .
  2. The previously owned object in * this (if any) is destroyed using traits :: destroy and then the storage is deallocated.
  3. p points to the new owned object.
After updating the objects owned by * this and other , if need_update is true , alloc is replaced with a copy of other. alloc .
If std:: is_copy_constructible_v < T > is false , the program is ill-formed.
3) If * this is valueless, then constructs an owned object with std:: forward < U > ( value ) using alloc . Otherwise, equivalent to ** this = std:: forward < U > ( value ) .
This overload participates in overload resolution only if all following conditions are satisfied:

Contents

Parameters

other - another indirect object whose owned value (if exists) is used for assignment
value - value to assign to or construct the owned value

Return value

* this

Exceptions

1) If any exception is thrown, the result of this - > valueless_after_move ( ) remains unchanged.
If an exception is thrown during the call to T ’s selected copy constructor, no effect.
If an exception is thrown during the call to T ’s copy assignment operator, the state of this - > p is as defined by the exception safety guarantee of T ’s copy assignment operator.
2) If any exception is thrown, there are no effects on * this or other .
noexcept specification:
noexcept ( std:: allocator_traits < Allocator > ::

propagate_on_container_move_assignment :: value

|| std:: allocator_traits < Allocator > :: is_always_equal :: value )

Example

This section is incomplete
Reason: no example