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

 

C++

Language

Standard Library Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

 

Utilities library

Type support (basic types, RTTI, type traits)
Dynamic memory management
Error handling
Program utilities
Variadic functions
Library feature-test macros
Date and time
Function objects
initializer_list (C++11)
bitset
hash (C++11)
integer_sequence (C++14)
Relational operators (deprecated in C++20)
rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=
Comparisons (C++20)
strong_order weak_order partial_order strong_equal weak_equal	strong_ordering weak_ordering partial_ordering strong_equality weak_equality	is_eqis_neqis_ltis_lteqis_gtis_gteq
common_comparison_category
Common vocabulary types
pair tuple (C++11) apply (C++17) make_from_tuple (C++17)	optional (C++17) any (C++17) variant (C++17)
Swap, forward and move
swap
exchange (C++14)
forward (C++11)
move (C++11)
move_if_noexcept (C++11)
Elementary string conversions
to_chars (C++17)
from_chars (C++17)
chars_format (C++17)
Type operations
declval (C++11)
as_const (C++17)
launder (C++17)

 

Function objects

Function wrappers function (C++11) mem_fn (C++11) bad_function_call (C++11)	Partial function application bind_front (C++20) bind (C++11) is_bind_expression (C++11) is_placeholder (C++11) _1, _2, _3, ... (C++11)
Function invocation invoke (C++17) Identity function object identity (C++20)	Reference wrappers reference_wrapper (C++11) refcref (C++11)(C++11) unwrap_referenceunwrap_ref_decay (C++20)(C++20)
Operator wrappers
plus minus negate multiplies divides modulus logical_and logical_or logical_not	equal_to not_equal_to greater less greater_equal less_equal bit_and bit_or bit_xor bit_not (C++14)
Negators not_fn (C++17) Searchers default_searcher (C++17) boyer_moore_searcher (C++17) boyer_moore_horspool_searcher (C++17)	Constrained comparators ranges::equal_to (C++20) ranges::not_equal_to (C++20) ranges::greater (C++20) ranges::less (C++20) ranges::greater_equal (C++20) ranges::less_equal (C++20)
Old binders and adaptors
unary_function (until C++17) binary_function (until C++17) ptr_fun (until C++17) pointer_to_unary_function (until C++17) pointer_to_binary_function (until C++17) mem_fun (until C++17) mem_fun_tmem_fun1_tconst_mem_fun_tconst_mem_fun1_t (until C++17)(until C++17)(until C++17)(until C++17) not1 (until C++20) not2 (until C++20)	binder1stbinder2nd (until C++17)(until C++17) bind1stbind2nd (until C++17)(until C++17) mem_fun_ref (until C++17) mem_fun_ref_tmem_fun1_ref_tconst_mem_fun_ref_tconst_mem_fun1_ref_t (until C++17)(until C++17)(until C++17)(until C++17) unary_negate (until C++20) binary_negate (until C++20)

 

std::function

Member functions

function::function

function::~function

function::operator=

function::swap

function::assign (until C++17)

function::operator bool

function::operator()

function::target_type

function::target

Non-member functions

operator==operator!=

std::swap(std::function)

Helper classes

std::uses_allocator<std::function> (until C++17)

Deduction guides(C++17)

 

function& operator=( const function& other );	(1)	(since C++11)
function& operator=( function&& other );	(2)	(since C++11)
	(3)
function& operator=( std::nullptr_t );			(since C++11) (until C++17)
function& operator=( std::nullptr_t ) noexcept;			(since C++17)
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.

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
- F must meet the requirements of Callable.

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).

See also

assign (until C++17)

assigns a new target (public member function)