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Re: Why no variables?

From: David Landwehr <david.landwehr@picoforms.com>
Date: Wed, 07 Feb 2007 16:47:11 +0100
Message-ID: <45C9F47F.9070609@picoforms.com>
To: "Clark, John" <CLARKJ2@ccf.org>
CC: www-forms@w3.org

I wrote up an extension for variable on exforms.org 
(http://exforms.org/variable.html). It is a *very* good idea to use 
variables as it is easy to author and can also speed up XPath evaluation 
when there are many expressions.

Best regards,
David


Clark, John skrev:
> As I've been working with XForms (primarily 1.1), I've been wondering
> why the spec doesn't allow for variables.  In particular, I would think
> that variables would be useful in event handlers (actions), and I think
> they'd be pretty straightforward to define.  I imagine them looking
> something like this (where the `xf` prefix maps to the XForms namespace
> and the `ev` prefix maps to the XML Events namespace):
>
>   <xf:action ev:event="some-event">
>     <xf:variable name="actionContext" value="current()"/>
>     <xf:variable name="target" value="xpath/to/target"/>
>     <xf:insert origin="$actionContext/new" context="$target"/>
>     <xf:delete nodeset="$target/old"/>
>   </xf:action>
>
> At the very least, then, variables would be scoped to the containing
> action handler; we could then have some interesting discussion about
> whether or not we'd want to expand that scope to the outermost action
> handler or even to a global scope.
>
> Take care,
>
>     John L. Clark  |  Systems Analyst
>                    |  Cardio-Thoracic Surgery Research
>  Cleveland Clinic  |  9500 Euclid Ave.   |  Cleveland, OH 44195
>                    |  (216) 445-6011
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Received on Wednesday, 7 February 2007 15:47:36 GMT

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