std::experimental::packaged_task<R(Args...)>::packaged_task (library fundamentals TS)
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< cpp | experimental | lib extensions | packaged task
packaged_task() noexcept; |
(1) | (library fundamentals TS) |
|
template
<
class F >
explicit packaged_task( F&& f ) ; |
(2) | (library fundamentals TS) |
|
template
<
class F, class Allocator >
explicit packaged_task( std::allocator_arg_t, const Allocator& alloc, F&& f ) ; |
(3) | (library fundamentals TS) |
|
packaged_task( const packaged_task& ) = delete;
|
(4) | (library fundamentals TS) |
packaged_task( packaged_task&& rhs ) noexcept; |
(5) | (library fundamentals TS) |
Constructs a new std::experimental::packaged_task object.
1) Constructs a
std::experimental::packaged_task object with no task and no shared state.
2) Constructs a
std::experimental::packaged_task object with a shared state and a copy of the task, initialized with
std::forward
<F>
(f)
. This constructor does not participate in overload resolution if
std::decay
<F>
::
type
is the same type as
std::packaged_task
<R(ArgTypes...)
>
3) Constructs a
std::experimental::packaged_task object with a shared state and a copy of the task, initialized with
std::forward
<F>
(f)
. Uses the provided allocator to allocate memory necessary to store the task, which is treated as a type-erased allocator (see below). This constructor does not participate in overload resolution if
std::decay
<F>
::
type
is the same type as
std::packaged_task
<R(ArgTypes...)
>
4) The copy constructor is deleted,
std::experimental::packaged_task is move-only.
5) Constructs a
std::experimental::packaged_task with the shared state and task formerly owned by rhs, leaving rhs
Type-erased allocator
The constructors of packaged_task taking an allocator argument alloc treats that argument as a type-erased allocator. The memory resource pointer used by packaged_task
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 ( ) |
| std::nullptr_t | The value of std::experimental::pmr::get_default_resource ( ) |
| A pointer type convertible to std::experimental::pmr::memory_resource * |
static_cast < std::experimental::pmr::memory_resource * > (alloc) |
| A specialization of std::experimental::pmr::polymorphic_allocator |
alloc.resource() |
| 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 packaged_task
|
| None of the above | The program is ill-formed. |
Parameters
| f | - | the callable target (function, member function, lambda-expression, functor) to execute |
| alloc | - | the allocator to use when storing the task |
| rhs | - | the std::experimental::packaged_task to move from
|
Exceptions
4) (none)