std::function<R(Args...)>::operator= (3) - Linux Manuals

std::function<R(Args...)>::operator=: std::function<R(Args...)>::operator=

NAME

std::function<R(Args...)>::operator= - std::function<R(Args...)>::operator=

Synopsis

function& operator=( const function& other ); (1) (since C++11)
function& operator=( function&& other ); (2) (since C++11)
function& operator=( std::nullptr_t ); (since C++11)
                                                                               (until C++17)
function& operator=( std::nullptr_t ) noexcept; (since C++17)
template< class F > (3) (4) (since C++11)
function& operator=( F&& f );
template< class F > (5) (since C++11)
function& operator=( std::reference_wrapper<F> f ) noexcept;

Assigns a new target to std::function.
1) Assigns a copy of target of other, as if by executing function(other).swap(*this);
2) Moves the target of other to *this. other is in a valid state with an unspecified value.
3) Drops the current target. *this is empty after the call.
4) Sets the target of *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.
(since C++14)
5) Sets the target of *this to a copy of f, as if by executing function(f).swap(*this);

Parameters

other - another std::function object to copy the target of
f - a callable to initialize the target with

Type requirements

Return value

*this

Notes

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_#2386).