- From: <bugzilla@wiggum.w3.org>
- Date: Wed, 15 Apr 2009 15:00:27 +0000
- To: www-xml-schema-comments@w3.org
http://www.w3.org/Bugs/Public/show_bug.cgi?id=5023
Noah Mendelsohn <noah_mendelsohn@us.ibm.com> changed:
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--- Comment #10 from Noah Mendelsohn <noah_mendelsohn@us.ibm.com> 2009-04-15 15:00:27 ---
Michael Kay writes:
> using a specialized mechanism such as identity
> constraints rather than a general mechanism like
> assertions may result in a more focused and
> intelligible error message when the condition is
> violated.
Yes, indeed. Perhaps the TAG finding Rule of Least Power
(http://www.w3.org/2001/tag/doc/leastPower.html) is pertinent to consideration
of these tradeoffs.
> it's a lot easier for an implementation to enforce
> identity constraints and CTA while processing the
> document in a streaming manner than it is to
> enforce assertions
Sigh. I can't help remembering all the debates about whether insisting on a
suitable subset of XPath would have made this less of a concern. Too late to
reopen that, but I do find it disappointing to find out that after all, you as
a skilled implementer wind up warning users away from assertions exactly
because of this foreseeable concern. That doesn't make the tradeoff we chose
wrong, but I remain somewhat uncomfortable with it.
Noah
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Received on Wednesday, 15 April 2009 15:00:44 UTC