Re: Several updates to XPath Expressions Module

Hi Nick,

The XPath expression spec itself still contains the language about XPath 
version and XPath 1.0 compatibility mode. 
This is consistent with the resolution we made to keep but soften XPath 
1.0 when we changed XForms version from 1.2 to 2.0.
I now there has been a proposal to just remove it from Leigh, but I've 
expressed my opposition to that, including an email that got no response.

The rationale to keep the functionality is based on the simple fact that 
it is functionality easily achieved by compatibility mode that smooths 
transition from XForms 1.x to 2.0.

As for where to add these functions, I thought of possibly creating a 
separate section, but in the end I just went with the current organization 
for a few reasons.  First, it is not worth spending a lot of time 
spit-shining this aspect of the spec when a note within the function 
description as I've done is good enough.  Second, it seemed like there 
were other functions that would have to move, like id().  Third, it seemed 
like the rationale was not just XPath 1.0 compat but authoring ease, due 
to consistent xf namespace usage and in some cases complexity reduction 
(compare the example of eval-in-context() with the same one in eval()). 

The net is that I'd rather we focus on higher value issues, like the fact 
that the XForms 2.0 says that the expressions module defines how the 
expression produces compute references, but then the XPath expression 
module doesn't define it.  I'm going to try to deal with that today.

Thanks,
John M. Boyer, Ph.D.
Distinguished Engineer, IBM Forms and Smarter Web Applications
IBM Canada Software Lab, Victoria
E-Mail: boyerj@ca.ibm.com 

Twitter: http://twitter.com/johnboyerphd
Blog: http://www.ibm.com/developerworks/blogs/page/JohnBoyer
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From:   Nick Van den Bleeken <Nick.Van.den.Bleeken@inventivegroup.com>
To:     John Boyer/CanWest/IBM@IBMCA
Cc:     "<public-forms@w3.org>" <public-forms@w3.org>
Date:   17/04/2012 12:19 AM
Subject:        Re: Several updates to XPath Expressions Module



John, 

Great work! I have one remark though ;) the actions to add 
xf:veal-in-context(), xf:replace() and xf:matches() pre-date the decision 
to target XPath 2.0 for XForms 2.0. And you don't need those functions if 
you have an XPath 2.0 engine.

We have three possibilities:
1) Add those functions to XForms 2.0 like you have done
2) Don't  add those functions to XForms 2.0 because you don't need them in 
XPath 2.0
3) Create a separate section were we group all the functions that are no 
longer needed if you have an XPath 2.0 engine, but are there for 
'backwards compatibility'.

Kind regards,

Nick Van den Bleeken
R&D Manager

Phone: +32 3 425 41 02
Office fax: +32 3 821 01 71
nick.van.den.bleeken@inventivegroup.com
www.inventivedesigners.com




On 17 Apr 2012, at 00:36, John Boyer wrote:

See http://www.w3.org/MarkUp/Forms/wiki/XPath_Expressions_Module 

1) Added functions xf:eval() and xf:eval-in-context() per Action-1836 (
https://www.w3.org/2005/06/tracker/xforms/actions/1836) 

2) Added functions xf:matches() and  xf:replace() per Action-1813 (
https://www.w3.org/2005/06/tracker/xforms/actions/1813) 

3) Amended existing example descriptions and added example to 
adjust-dateTime-to-timezone() per Action-1805 (
https://www.w3.org/2005/06/tracker/xforms/actions/1805) 

4) Fixed return type of xf:attribute() function, which claimed to return 
an element() 

5) Added the frequently used but undefined namespace prefix "xf" 

6) Changed example in index() and valid() functions to remove unnecessary 
xforms namespacing and add following descriptions.   

Note that <xforms:instance> remains in examples of instance() and 
current() because the examples would break if prefix removed.  Those 
examples use the best practice of putting xmlns="" on the 
<xforms:instance> element to avoid infesting the XML data with xmlns="". 

7) Fixed one incorrectly placed id anchor for boolean functions. 

8) Added id anchor spans for almost all functions in the spec 

9) Made numerous fixes to spurious div end tags 

10) Added one missing "Examples:" and removed one duplicate "Examples:" 

11) Made some changes to the acknowledgements (Remaining issues: Is Steven 
Pemberton entry accurate, what do we do about past members) 

12) Changed editor list :-) 

Cheers, 
John M. Boyer, Ph.D.
Distinguished Engineer, IBM Forms and Smarter Web Applications
IBM Canada Software Lab, Victoria
E-Mail: boyerj@ca.ibm.com 

Twitter: http://twitter.com/johnboyerphd
Blog: http://www.ibm.com/developerworks/blogs/page/JohnBoyer
Blog RSS feed: 
http://www.ibm.com/developerworks/blogs/rss/JohnBoyer?flavor=rssdw


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