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[Bug 5445] [XPath] Undocumented incompatibility with compatibility mode "true" for general comparison involving boolean

From: <bugzilla@wiggum.w3.org>
Date: Thu, 31 Jan 2008 21:07:08 +0000
To: public-qt-comments@w3.org
Message-Id: <E1JKgcm-00031Q-1A@wiggum.w3.org>


------- Comment #1 from zongaro@ca.ibm.com  2008-01-31 21:07 -------
I did some research into the history of the current wording of the effect of
XPath 1.0 compatibility mode on general comparison operators.  This text first
appeared in the October 2004 working draft of XPath 2.0 [5] in response to a
public comment.[6]  That decision was made at the Sept. 9, 2004 meeting of the
XSL WG.[7]  (I haven't tracked down the corresponding XQuery WG or joint
meeting decision.)

It's not clear from the discussion of the original issue whether the working
groups noted the fact that the changes would introduce a new incompatibility
for "true() > number('0.5')".  Assuming that really was the intent of the
working groups, a new item should be added to section I.1 of XPath 2.0:

  "7. If one operand in a general comparison is a single atomic value of type
      xs:boolean, the other operand is converted to xs:boolean when XPath 1.0
      compatibility mode is set to true.  In XPath 1.0, if neither operand of a
      comparison operation using the <, <=, > or >= operator was a node set,
      both operands were converted to a number.  The result of the expression
      <code>true() &gt; number('0.5')</code> is true in XPath 1.0, and it is
      and false in XPath 2.0 processor when compatibility mode is set to true."

Alternatively, if the working groups did not intend to introduce this
incompatibility, they might consider restricting the first item in the first
numbered list in section 3.5.2 of XPath 2.0 to apply only in the case of the =
and != general comparison operators.

[5] http://www.w3.org/TR/2004/WD-xpath20-20041029/#id-general-comparisons
[6] http://lists.w3.org/Archives/Public/public-qt-comments/2004Feb/0298.html
[7] http://lists.w3.org/Archives/Member/w3c-xsl-wg/2004Sep/0012.html (Members
Received on Thursday, 31 January 2008 21:07:14 UTC

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