cppdraft_translate/cppdraft/exec/opstate.md

[exec.opstate]

33 Execution control library [exec]

33.8 Operation states [exec.opstate]

33.8.1 General [exec.opstate.general]

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The operation_state concept defines the requirements of an operation state type ([exec.async.ops]).

namespace std::execution {templateconcept operation_state =derived_from<typename O::operation_state_concept, operation_state_t> &&requires (O& o) { start(o); };}

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If an operation_state object is destroyed during the lifetime of its asynchronous operation ([exec.async.ops]), the behavior is undefined.

[Note 1:

The operation_state concept does not impose requirements on any operations other than destruction and start, including copy and move operations.

Invoking any such operation on an object whose type models operation_state can lead to undefined behavior.

— end note]

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The program is ill-formed if it performs a copy or move construction or assignment operation on an operation state object created by connecting a library-provided sender.

33.8.2 execution​::​start [exec.opstate.start]

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The name start denotes a customization point object that starts ([exec.async.ops]) the asynchronous operation associated with the operation state object.

For a subexpression op, the expression start(op) is ill-formed if op is an rvalue.

Otherwise, it is expression-equivalent toMANDATE-NOTHROW(op.start()).

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If op.start() does not start ([exec.async.ops]) the asynchronous operation associated with the operation state op, the behavior of calling start(op) is undefined.