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RE: XForms CR - 3.3.1etc "XPath Extension Functions"

From: John Boyer <JBoyer@PureEdge.com>
Date: Wed, 13 Nov 2002 11:43:10 -0800
Message-ID: <7874BFCCD289A645B5CE3935769F0B524527C4@tigger.pureedge.com>
To: <AndrewWatt2001@aol.com>
Cc: <www-forms@w3.org>, <www-forms-editor@w3.org>, <Xforms@yahoogroups.com>
Hi Andrew,
 
First of all, I have to ask whether you are *trying* to be condescending?  Your emails are really coming across that way, whether intended or not.  So, if the latter, then perhaps you could have someone edit the emails first.
 
As for XPath, I have reflected on it for quite a number of years now. Please see, for example, the XML Canonicalization recommendation ( www.w3.org/TR/xml-c14n). The XPath Rec is quite clear that the initial context is "a function library", not just the core function library.  It then defines a function library as a mapping from function names to functions.  Then it goes on to indicate that, whatever function library is provided to XPath, it must contain the functions named in the core library defined by XPath.
 
Please see XML Signatures ( www.w3.org/TR/xmldsig-core) for another W3C recommendation that provides additional functions to the function library passed to the XPath implementation.  If one were to cry foul on any W3C work, I would figure it would be XPointer, which (last I checked) overloads the core library function names to have location-set parameters and return types rather than node-set.  This would seem to violate the definition of function library given in XPath 1.0.
 
XForms, however, does not do this.  It consumes only the XPath data model and expression language, and its extension functions comply with the requirements set forth in XPath 1.0.
 
John Boyer, Ph.D.
Senior Product Architect
PureEdge Solutions Inc.
  
 

-----Original Message-----
From: AndrewWatt2001@aol.com [mailto:AndrewWatt2001@aol.com]
Sent: Wednesday, November 13, 2002 11:14 AM
To: John Boyer
Cc: www-forms@w3.org; www-forms-editor@w3.org; Xforms@yahoogroups.com
Subject: Re: XForms CR - 3.3.1etc "XPath Extension Functions"


In a message dated 13/11/2002 19:01:07 GMT Standard Time, JBoyer@PureEdge.com writes:




Hi Andrew,

Please reread the introduction section of the XPath Rec.

Thanks,
John Boyer, Ph.D.
Senior Product Architect
PureEdge Solutions Inc.


-----Original Message-----
From: AndrewWatt2001@aol.com [mailto:AndrewWatt2001@aol.com]
Sent: Wednesday, November 13, 2002 4:23 AM
To: www-forms@w3.org; www-forms-editor@w3.org; Xforms@yahoogroups.com
Subject: XForms CR - 3.3.1etc "XPath Extension Functions"




In 3.3.1 (and elsewhere in the CR) reference is made to "XPath Extension 
Functions".

As I recall, the XPath 1.0 Recommendation does not define any mechanism for 
creating extension functions.

Perhaps the XForms WG intended to reference a mechanism defined other than in 
the XPath 1.0 Recommendation?

Andrew Watt



John,

Nothing in a quick skim through the Introduction seems to me to contradict what I wrote earlier.

Was this the section you were referring to? ...

"Both XSLT and XPointer extend XPath by defining additional functions; some of these functions operate on the four basic types; others operate on additional data types defined byXSLT and XPointer.".

The quoted section indicates that XSLT and XPointer provide mechanisms for extension functions.

I see no reference to "extension functions" which are "XPath extension functions". If the XForms CR wishes to refer to "XSLT extension functions" or "XPointer extension functions" that's fine by me. I just think it may be incorrect for the XForms CR to refer to those as "XPath extensions functions".

On reflection, do you agree?

Regards

Andrew Watt 
Received on Wednesday, 13 November 2002 14:44:01 GMT

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