W3C home > Mailing lists > Public > xmlschema-dev@w3.org > June 2008

Re: UPA example

From: Pete Cordell <petexmldev@codalogic.com>
Date: Wed, 25 Jun 2008 11:49:10 +0100
Message-ID: <001c01c8d6b1$2fad4860$ea00a8c0@Codalogic>
To: "Michael Kay" <mike@saxonica.com>, "'Boris Kolpackov'" <boris@codesynthesis.com>, <xmlschema-dev@w3.org>

----- Original Message ----- From: "Michael Kay"
To: "'Boris Kolpackov'"

>> Yes, I also think it won't be valid unless the parser in 1.1
>> is expected to do backtracking. I am also wondering if the
>> authors of this change to the spec considered how hard it
>> will be to explain something like this to a user.
> I think this is a pretty unrealistic example. I think that in most 
> practical
> cases the new rules will have much more intuitive behaviour than the old
> rules. Perhaps it would be even more intuitive if backtracking were added,
> but I think most WG members regard that as a bridge too far.

So I take it that under the XSD 1.1 rules, the instance would be valid and 
have particle assigment corresponding to:

 <apple/> validated by element
 <apple/> validated by any
 <apple/> validated by any

Rather than:

 <apple/> validated by element
 <apple/> validated by any
 <apple/> validated by element

Personally I think that, subject to occurrence constraints, the particle 
that is currently gobbling up input, should have priority (i.e. they're 
greedy).  That seems a lot easier to implement, it's a lot easier for schema 
authors/users to understand and has similarities to how regular expressions 
behave.  I think it might give the wrong result in some situations, but I 
don't think it will be wrong in any more situations than the current 1.1 
rules.  I also think that in situations where behaviour similar to 1.1 rules 
is preferred the xs:any notQName attribute can come to the rescue.


Pete Cordell
For XML C++ data binding visit http://www.codalogic.com/lmx/
Received on Wednesday, 25 June 2008 10:50:30 UTC

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