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Descriptor service requirements

A descriptor service must meet the requirements for an I/O object service with support for movability, as well as the additional requirements listed below.

In the table below, X denotes a descriptor service class, a and ao denote values of type X, b and c denote values of type X::implementation_type, n denotes a value of type X::native_handle_type, ec denotes a value of type error_code, i denotes a value meeting IoControlCommand requirements, and u and v denote identifiers.

Table 9. DescriptorService requirements

expression

return type

assertion/note
pre/post-condition

X::native_handle_type

The implementation-defined native representation of a descriptor. Must satisfy the requirements of CopyConstructible types (C++ Std, 20.1.3), and the requirements of Assignable types (C++ Std, 23.1).

a.construct(b);

From IoObjectService requirements.
post: !a.is_open(b).

a.destroy(b);

From IoObjectService requirements. Implicitly cancels asynchronous operations, as if by calling a.close(b, ec).

a.move_construct(b, c);

From IoObjectService requirements. The underlying native representation is moved from c to b.

a.move_assign(b, ao, c);

From IoObjectService requirements. Implicitly cancels asynchronous operations associated with b, as if by calling a.close(b, ec). Then the underlying native representation is moved from c to b.

a.assign(b, n, ec);

error_code

pre: !a.is_open(b).
post: !!ec || a.is_open(b).

a.is_open(b);

bool

const X& u = a;
const X::implementation_type& v = b;
u.is_open(v);

bool

a.close(b, ec);

error_code

If a.is_open() is true, causes any outstanding asynchronous operations to complete as soon as possible. Handlers for cancelled operations shall be passed the error code error::operation_aborted.
post: !a.is_open(b).

a.native_handle(b);

X::native_handle_type

a.cancel(b, ec);

error_code

pre: a.is_open(b).
Causes any outstanding asynchronous operations to complete as soon as possible. Handlers for cancelled operations shall be passed the error code error::operation_aborted.

a.io_control(b, i, ec);

error_code

pre: a.is_open(b).



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