std::experimental::packaged_task<R(Args...)>::packaged_task (library fundamentals TS)
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packaged_task() noexcept;
(1)
(library fundamentals TS)
template< class F >
explicit packaged_task( F&& f );
(2)
(library fundamentals TS)
explicit packaged_task( F&& f );
template< class F, class Allocator >
explicit packaged_task( std::allocator_arg_t, const Allocator& alloc, F&& f );
(3)
(library fundamentals TS)
explicit packaged_task( std::allocator_arg_t, const Allocator& alloc, F&& f );
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.[edit] 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)
std::experimental::pmr::memory_resource * static_cast<std::experimental::pmr::memory_resource *>(alloc)
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.
[edit] 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
[edit] Exceptions
2,3) Any exceptions thrown by copy/move constructor of f and possiblly std::bad_alloc if the allocation fails.
4) (none)