function& operator=( const function& other ); | (1) | (since C++11) |
function& operator=( function&& other ); | (2) | (since C++11) |
function& operator=( std::nullptr_t ) noexcept; | (3) | (since C++11) |
template< class F > function& operator=( F&& f ); | (4) | (since C++11) |
template< class F > function& operator=( std::reference_wrapper<F> f ) noexcept; | (5) | (since C++11) |
Assigns a new target to std::function.
other, as if by executing function(other).swap(*this);
other to *this. other is in a valid state with an unspecified value.*this is empty after the call.*this to the callable f, as if by executing function(std::forward<F>(f)).swap(*this);. This operator does not participate in overload resolution unless f is Callable for argument types Args... and return type R.*this to a copy of f, as if by executing function(f).swap(*this);
| other | - | another std::function object to copy the target of |
| f | - | a callable to initialize the target with |
| Type requirements | ||
-F must meet the requirements of Callable. |
||
*this.
Even before allocator support was removed from std::function in C++17, these assignment operators use the default allocator rather than the allocator of *this or the allocator of other (see LWG issue 2386).
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 2132 | C++11 | the overload taking a Callable object might be ambiguous | constrained |
| LWG 2401 | C++11 | assignment operator from std::nullptr_t not required to be noexcept | required |
|
(C++23) | replaces or destroys the target (public member function of std::move_only_function) |
|
(removed in C++17) | assigns a new target (public member function) |
© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
https://en.cppreference.com/w/cpp/utility/functional/function/operator%3D