std::experimental::packaged_task::packaged_task(libraryfundamentalsTS) (3) Linux Manual Page

std::experimental::packaged_task<R(Args…)>::packaged_task(libraryfundamentalsTS) – std::experimental::packaged_task<R(Args…)>::packaged_task(libraryfundamentalsTS)

Synopsis

packaged_task() noexcept;
(1)(library fundamentals TS)

    template <class F>
    (2)(library fundamentals TS)

        explicit packaged_task(F &&f);

template <class F, class Allocator>
(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.
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 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 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)