2.5 KiB
[exec.snd.general]
33 Execution control library [exec]
33.9 Senders [exec.snd]
33.9.1 General [exec.snd.general]
Subclauses [exec.factories] and [exec.adapt] define customizable algorithms that return senders.
Each algorithm has a default implementation.
Let sndr be the result of an invocation of such an algorithm or an object equal to the result ([concepts.equality]), and let Sndr be decltype((sndr)).
Let rcvr be a receiver of type Rcvr with associated environment env of type Env such that sender_to<Sndr, Rcvr> is true.
For the default implementation of the algorithm that produced sndr, connecting sndr to rcvr and starting the resulting operation state ([exec.async.ops]) necessarily results in the potential evaluation ([basic.def.odr]) of a set of completion operations whose first argument is a subexpression equal to rcvr.
Let Sigs be a pack of completion signatures corresponding to this set of completion operations, and let CS be the type of the expression get_completion_signatures<Sndr, Env>().
Then CS is a specialization of the class template completion_signatures ([exec.cmplsig]), the set of whose template arguments is Sigs.
If none of the types in Sigs are dependent on the type Env, then the expression get_completion_signatures() is well-formed and its type is CS.
If a user-provided implementation of the algorithm that produced sndr is selected instead of the default:
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Any completion signature that is in the set of types denoted by completion_signatures_of_t<Sndr, Env> and that is not part of Sigs shall correspond to error or stopped completion operations, unless otherwise specified.
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If none of the types in Sigs are dependent on the type Env, thencompletion_signatures_of_t andcompletion_signatures_of_t<Sndr, Env> shall denote the same type.