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Re: ACTION-2211: Redefine terms via xdm instead of xpath[1, 2]

From: Steven Pemberton <steven.pemberton@cwi.nl>
Date: Wed, 16 Jan 2019 11:43:07 +0100
To: public-xformsusers@w3.org, "XForms Users Community Group Issue Tracker" <sysbot+tracker@w3.org>
Message-ID: <op.zvphd5eismjzpq@steven-xps>
I am in the midst of this action, and while most of it is done, I'm  
struggling with two sections, which I would ask you to read so we can  
discuss.

One is section 6.5 The function Element
https://www.w3.org/community/xformsusers/wiki/XForms_2.0#The_function_Element

which has sentences like this:

"The result of a function is a sequence of atomic values and/or nodes. If  
the result type of the function is specified with the as attribute, the  
result value of the function as specified by the function body is  
converted to the required type (specified using a SequenceType, as defined  
in XPath 2.0), using the function conversion rules. It is a type error if  
this conversion fails."

"The rules for converting the values of the actual arguments supplied in  
the function call to the types required by each parameter are defined in  
[XPath 2.0]. The rules that apply are those for the case where XPath 1.0  
compatibility mode is set to false."

"Within the body of a custom function, the evaluation focus is initially  
undefined; this means that any attempt to reference the context item,  
context position, or context size is a non-recoverable dynamic error  
([err:XPDY0002] as defined in XPath 2.0)"


The other is section 6.2 Typed Values
https://www.w3.org/community/xformsusers/wiki/XForms_2.0#Typed_Values
which I now realise I don't understand the purpose of entirely.

I think the argument is

"Types in XForms are principally used to check the validity of strings  
provided as values to nodes. However, the expression language may also use  
those types during the evaluation of expressions using those nodes.

If the evaluation of an expression fails because of a type error:
* for a calculate expression, the result is the empty sequence
* for a constraint expression, the result is false()
* for other bind computed expressions, the result is not applied to the  
node
* for all other expressions, an xforms-expression-error event is  
dispatched to the element containing the expression."

Do you think there is any other part of that section that is normative  
that I have missed?

Steven


On Wed, 09 Jan 2019 15:09:26 +0100, XForms Users Community Group Issue  
Tracker <sysbot+tracker@w3.org> wrote:

> ACTION-2211: Redefine terms via xdm instead of xpath[1, 2]
>
> https://www.w3.org/2005/06/tracker/xforms/actions/2211
>
> Assigned to: Steven Pemberton
Received on Wednesday, 16 January 2019 10:43:31 UTC

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