std::experimental::packaged_task<R(Args...)>:: packaged_task (library fundamentals TS)
From cppreference.com
<
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
with no shared state and a moved-from task.
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
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
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
object.
|
| 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
2,3)
Any exceptions thrown by copy/move constructor of
f
and possiblly
std::bad_alloc
if the allocation fails.
4)
(none)