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Re: [SCXML] Question regarding the meaning and purpose of type 'location expression in namelist and param location attributes

From: David Junger <tffy@free.fr>
Date: Tue, 28 Oct 2014 10:39:58 +0100
Message-Id: <B362C49F-EAB3-4BCC-A6A8-1BEBA1D2B9E9@free.fr>
To: "www-voice@w3.org" <www-voice@w3.org>
Le 28 okt 2014 à 03:31, Ate Douma <ate@douma.nu> a écrit :
> 
> AFAICT the purpose of the location attribute is only to yield the value at the specified location, not the location itself.
> But then: why not just and only use the expr attribute always, which should be giving the exact same result, if it targets a datamodel location?

Yes, the location expression itself matters when you use 'location' rather than 'value'. It is tied to the use of empty <finalize/> when receiving events back from the invocation: in that case, params sent back with the name assigned to of one of the locations on starting the invocation will have their value copied into that location.
I don't recall that there is any other use, and that one is pretty marginal. But the definition clearly states that a location expression can be any valid left-hand-side value in the ECMAScript datamodel.
The tests do not currently check for full conformance with this. They should use a different name and location, for starters. And they should check that params with a name that wasn't associated with a location in the <invoke> are not copied.

… or we could just drop this pretty complex, obscure, and marginal feature.

			David
Received on Tuesday, 28 October 2014 09:40:22 UTC

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