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Re: SVG and XForms

From: Nick Van den Bleeken <Nick.Van.den.Bleeken@inventivegroup.com>
Date: Wed, 4 Apr 2012 13:31:48 +0000
To: Erik Bruchez <ebruchez@gmail.com>
CC: "public-xformsusers@w3.org" <public-xformsusers@w3.org>
Message-ID: <10E2C0E2-6D69-4A44-8678-F6EAB5A3FEB1@inventivegroup.com>

An (XPath) expression can return any sequence of items, it is the responsibility of who uses the expression to limit the return type if required.

So if you see in the spec the ref attribute, depending on where it is used, limits the return type to a sequence of nodes or a single node:

[1] states that the ref and node set attribute on the bind element only allows expressions that select sets of nodes.
[2] states that the ref attribute on submission selects an instance data node
[3] states that the ref attribute on the header element has no restrictions -> can be an atomic value (or sequence)
[4] states that the ref attributes used as single node binding has no restrictions -> can be an atomic value (or sequence)

Maybe we should make this more clear, but when I wanted to address this issue a couple months ago, I came to the conclusion that it was already addressed by the wording of the XForms 1.1 spec.

Kind regards,

Nick Van den Bleeken

1: http://www.w3.org/MarkUp/Forms/wiki/XForms_2.0#structure-bind-element
2: http://www.w3.org/MarkUp/Forms/wiki/XForms_2.0#submit-submission-element
3: http://www.w3.org/MarkUp/Forms/wiki/XForms_2.0#submit-header
4: http://www.w3.org/MarkUp/Forms/wiki/XForms_2.0#structure-attrs-nodeset

On 04 Apr 2012, at 01:22, Erik Bruchez wrote:

>> I'm still disturbed by @ref use because a Binding expression should return
>> nodes not a value, am I right?
> In Orbeon Forms, @ref can return any sequence of items, not only
> nodes. Now the question is whether the working group in fact decided
> to do this. Nick, do you remember the details?
> The XForms 2.0 doc right now says [1] "Binding expression interpreted
> as specified in the expression module."
> The XPath Expressions Module [2] defines a Binding expression as "An
> [XPath 2.0] expression used in a binding". But certainly it should
> address the fact that a binding expression does not necessarily point
> to nodes, and how it deals with atomic values. Right now I don't find
> anything on that topic in the spec.
> Nick, do you have any feedback on this?
> -Erik
> [1] http://www.w3.org/MarkUp/Forms/wiki/XForms_2.0#Binding_Attributes
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