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Re: Checking if an extension function exists and implementation/version sniffing

From: Erik Bruchez <erik@bruchez.org>
Date: Tue, 1 Oct 2013 14:09:31 -0700
Message-ID: <CAAc0PEVOxgOji_3eS4oAkFvh+c1Y3Nmwr8TKZkEfiWhqVBcz+w@mail.gmail.com>
To: Eric van der Vlist <vdv@dyomedea.com>
Cc: "public-xformsusers@w3.org" <public-xformsusers@w3.org>, public-forms@w3.org
And BTW this is in response to this action item:

ACTION-1956 - Answer eric vd vlist's message on identifying available functions

-Erik


On Tue, Oct 1, 2013 at 2:07 PM, Erik Bruchez <erik@bruchez.org> wrote:
> Eric,
>
> We discussed this during our last XForms call.
>
> We discussed two solutions:
>
> 1. Import the XSLT 2 function-available() function:
>
> http://www.w3.org/TR/xslt20/#function-function-available
>
> Note that XPath 3 now has function-lookup(), but this cannot be used
> with XPath 2 as this requires support for function() items:
>
> http://www.w3.org/TR/2013/CR-xpath-functions-30-20130108/#func-function-lookup
>
> 2. Improved error handling in XForms
>
> This is a separate but related topic. XPath and action errors should
> be, at least optionally, recoverable. This way, if you have a an error
> in an action which uses an unknown function, you could recover from
> that, and deduct that there was an issue with an XPath expression.
>
> #1 would be easy, both at the spec level and for implementors. This
> would also be the most direct solutions to your requirement.
>
> #2 is more involved, but also more useful, and a more indirect way,
> and solves in general a slightly different problem.
>
> My proposal would be to do both for XForms 2.0. I have an action item
> to make a proposal for improved error handling already.
>
> Please let us know if you have any comments on this!
>
> -Erik
Received on Tuesday, 1 October 2013 21:10:20 UTC

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