I concur. "redefine" appears to be reaching into someone else's namespace, 
and is thus conceptually as well as syntactically dubious.

OTOH subtitution groups are a good implementation of 
inheritance/polymorphism.
We use it that way in Geography Markup Language, where we map classes to 
global elements.

Simon Cox

----- Original Message ----- 
From: "Michael Kay" <mike@s...>
To: "'Bryan Rasmussen'" <brs@i...>; <xmlschema-dev@w...>
Sent: Saturday, July 09, 2005 7:18 AM
Subject: RE: support for substitution groups, support for redefines?


>
> As far as I know Saxon supports redefines according to the spec, but:
>
> (a) there are very few test cases in the W3C test suite so it's hard to be
> sure
>
> (b) by the nature of the facility, the design is very fragile
>
> (c) even if you follow the spec and the product implements it correctly, 
> you
> can get into an awful mess
>
> therefore I wouldn't recommend using it.
>
> Substitution groups are fine, I don't see any problem with them.
>
> Michael Kay
> http://www.saxonica.com/
>
>> -----Original Message-----
>> From: xmlschema-dev-request@w...
>> [mailto:xmlschema-dev-request@w...] On Behalf Of Bryan Rasmussen
>> Sent: 07 July 2005 08:33
>> To: 'xmlschema-dev@w...'
>> Subject: support for substitution groups, support for redefines?
>>
>>
>>
>> Hi
>> Does anyone have a good overview of how well substitution groups and
>> redefines are supported in various processors. The last big
>> project where I
>> used redefines extensively about half a year ago I had to redo halfway
>> through after running into too many problems, problems where
>> the redefine
>> was proper and was supported by some processors but failed in
>> others, even
>> more insidious where cases where I had redefined incorrectly and it
>> functioned in some processors or in some test instances only
>> to fail later.
>> This has put me off redefines, now I'm on something where
>> redefines and
>> substitution groups are being proposed as the extensibility
>> mechanism. I've
>> had misgivings about substitution groups, finding them somewhat overly
>> complicated and have thus avoided them. How is their support?
>>
>> Cheers
>> Bryan Rasmussen
>>
>>
>
>
> 


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