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RE: Section 5.2.7 (PR#138)

From: Michael Kay <mike@saxonica.com>
Date: Thu, 14 Jun 2007 23:45:50 +0100
To: "'Steven Pemberton'" <xforms-issues@mn.aptest.com>
Cc: <w3c-xml-query-wg@w3.org>, <www-forms-editor@w3.org>
Message-ID: <022601c7aed5$c2874320$6401a8c0@turtle>


>From the point of view of typed XPath processing, a list of length 0-or-1 is
probably preferable to a union-with-"". For example, sum() in the list case
would ignore empty values, whereas in the union case it would give a type
error because an empty value is treated as a string. Similarly x[@a > 3]
would effectively ignore empty values of @a if treated as a list, but give a
type error if treated as a union.

>From a validation perspective, of course, there is no difference.

Michael Kay

> -----Original Message-----
> From: Steven Pemberton [mailto:xforms-issues@mn.aptest.com] 
> Sent: 14 June 2007 21:14
> To: mike@saxonica.com
> Cc: w3c-xml-query-wg@w3.org; www-forms-editor@w3.org
> Subject: Re: Section 5.2.7 (PR#138)
> Thanks for the comment. In fact the introductory paragraph 
> confused even us when we reread it :-)
> We are rewriting this paragraph to make it clear that all 
> datatypes here allow empty content. They will indeed be 
> defined as unions in the Schema for XForms 1.1.
> Best wishes,
> Steven Pemberton
> For the Forms WG
> >     C. It's not clear which of these data types allow empty 
> content and
> >     which don't. What is meant by "the indicated datatypes"? Also,
> >     there should be a more formal definition of these types, for
> >     example they could be defined either as a union of the base type
> >     with a zero-length string, or as a list of zero-or-one 
> items of the
> >     base type. Such a definition affects the semantics of XPath
> >     expressions applied to values of these types. We do not 
> understand
> >     paragraph 2, which appears to contradict paragraph 1.
> > 
> > 
> > 
Received on Thursday, 14 June 2007 22:46:05 GMT

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