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Add documentation for async-channel contracts and impersonators

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Alexis King 2015-01-16 01:21:49 -08:00 committed by Robby Findler
parent 3ab1ad8c93
commit 6e79a582f1
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pkgs/racket-doc/scribblings/reference/async-channels.scrbl
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@ -11,6 +11,8 @@
@note-lib-only[racket/async-channel]
@section{Creating and Using Asynchronous Channels}
@margin-note/ref{See also @secref["threadmbox"].}
An @deftech{asynchronous channel} is like a @tech{channel}, but it buffers
@ -105,5 +107,59 @@ limit); @resultItself{asychronous channel-put event}.}
(async-channel-put to-server 'quit)
]
@section{Contracts and Impersonators on Asynchronous Channels}
@defproc[(async-channel/c [c contract?]) contract?]{
Returns a contract that recognizes asynchronous channels. Values put into or
retrieved from the channel must match @racket[c].
If the @racket[c] argument is a flat contract or a chaperone contract, then the
result will be a chaperone contract. Otherwise, the result will be an
impersonator contract.
When an @racket[async-channel/c] contract is applied to an asynchronous channel,
the result is not @racket[eq?] to the input. The result will be either a
@tech{chaperone} or @tech{impersonator} of the input depending on the type of
contract.}
@defproc[(impersonate-async-channel [channel async-channel?]
[get-proc (any/c . -> . any/c)]
[put-proc (any/c . -> . any/c)]
[prop impersonator-property?]
[prop-val any] ...
...)
(and/c async-channel? impersonator?)]{
Returns an impersonator of @racket[channel], which redirects the
@racket[async-channel-get] and @racket[async-channel-put] operations.
The @racket[get-proc] must accept the value that @racket[async-channel-get]
produces on @racket[channel]; it must produce a replacement value, which is the
result of the get operation on the impersonator.
The @racket[put-proc] must accept the value passed to @racket[async-channel-put]
called on @racket[channel]; it must produce a replacement value, which is the
value passed to the put procedure called on the original channel.
The @racket[get-proc] and @racket[put-proc] procedures are called for all
operations that get or put values from the channel, not just
@racket[async-channel-get] and @racket[async-channel-put].
Pairs of @racket[prop] and @racket[prop-val] (the number of arguments to
@racket[impersonate-async-channel] must be odd) add
@tech{impersonator properties} or override @tech{impersonator property} values
of @racket[channel].}
@defproc[(chaperone-async-channel [channel async-channel?]
[get-proc (any/c . -> . any/c)]
[put-proc (any/c . -> . any/c)]
[prop impersonator-property?]
[prop-val any] ...
...)
(and/c async-channel? chaperone?)]{
Like @racket[impersonate-async-channel], but the @racket[get-proc] procedure
must produce the same value or a chaperone of the original value, and
@racket[put-proc] must produce the same value or a chaperone of the original
value.}