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

std::experimental::function<R(Args...)>::function: std::experimental::function<R(Args...)>::function

NAME

std::experimental::function<R(Args...)>::function - std::experimental::function<R(Args...)>::function

Synopsis

function() noexcept; (1) (library fundamentals TS)
function( std::nullptr_t ) noexcept; (2) (library fundamentals TS)
function( const function& other ); (3) (library fundamentals TS)
function( function&& other ); (4) (library fundamentals TS)
template< class F > (5) (library fundamentals TS)
function( F f );
template< class Alloc > (6) (library fundamentals TS)
function( std::allocator_arg_t, const Alloc& alloc ) noexcept;
template< class Alloc >
function( std::allocator_arg_t, const Alloc& alloc, (7) (library fundamentals TS)
std::nullptr_t ) noexcept;
template< class Alloc >
function( std::allocator_arg_t, const Alloc& alloc, (8) (library fundamentals TS)
const function& other );
template< class Alloc >
function( std::allocator_arg_t, const Alloc& alloc, (9) (library fundamentals TS)
function&& other );
template< class F, class Alloc > (10) (library fundamentals TS)
function( std::allocator_arg_t, const Alloc& alloc, F f );

Constructs a std::experimental::function from a variety of sources.
1-2) Creates an empty function.
3-4) Copies (3) or moves (4) the target of other to the target of *this. If other is empty, *this will be empty after the call too.
5) Initializes the target with a copy of f. If f is a null pointer to function or null pointer to member, *this will be empty after the call. This constructor does not participate in overload resolution unless f is Callable for argument types Args... and return type R.
6-10) Same as (1-5) except that alloc is used to allocate memory for any internal data structures that the function might use. These constructors treat alloc as a type-erased allocator (see below).
When the target is a function pointer or a std::reference_wrapper, small object optimization is guaranteed, that is, these targets are always directly stored inside the std::experimental::function object, no dynamic allocation takes place. Other large objects may be constructed in dynamic allocated storage and accessed by the std::experimental::function object through a pointer.
If a constructor moves or copies a function object, including an instance of std::experimental::function, then that move or copy is performed by using-allocator_construction with allocator this->get_memory_resource().

Type-erased allocator

The constructors of function taking an allocator argument alloc treats that argument as a type-erased allocator. The memory resource pointer used by function to allocate memory is determined using the allocator argument (if specified) as follows:

Type of alloc value of the memory resource pointer
Non-existent (no allocator specified at time of construction) The value of std::experimental::pmr::get_default_resource() at time of construction.
std::nullptr_t The value of std::experimental::pmr::get_default_resource() at time of construction
A pointer type convertible to static_cast<std::experimental::pmr::memory_resource*>(alloc)
std::experimental::pmr::memory_resource*
A specialization of alloc.resource()
std::experimental::pmr::polymorphic_allocator
Any other type meeting the Allocator requirements A pointer to a value of type std::experimental::pmr::resource_adaptor<A>(alloc), where A is the type of alloc. The pointer remains valid only for the lifetime of the function object.
None of the above The program is ill-formed.

Parameters

other - the function object used to initialize *this
f - a callable used to initialize *this
alloc - an allocator used for internal memory allocation

Type requirements

-
F must meet the requirements of Callable and CopyConstructible.

Exceptions

3,8) does not throw if other's target is a function pointer or a std::reference_wrapper, otherwise may throw std::bad_alloc or any exception thrown by the copy constructor of the stored callable object.
4) (none)
5,10) does not throw if f is a function pointer or a std::reference_wrapper, otherwise may throw std::bad_alloc or any exception thrown by the copy constructor of the stored callable object.
9) (none)

Example

 This section is incomplete
 Reason: no example