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RE: Deriving from xs:anySimpleType

From: Michael Kay <mike@saxonica.com>
Date: Fri, 17 Nov 2006 10:41:21 -0000
To: "'Henry S. Thompson'" <ht@inf.ed.ac.uk>, "'Sandy Gao'" <sandygao@ca.ibm.com>
Cc: <xmlschema-dev@w3.org>
Message-ID: <007601c70a34$ec769500$6401a8c0@turtle>

A couple of questions:

(a) is there a rule already that prevents a non-vacuous restriction from
anySimpleType, that is, a restriction containing facets?

(b) Sandy seemed to suggest that if you do such a non-vacuous restriction,
the type you get *is* anySimpleType, rather than being a new type derived
from it. That seems preferable to me in the case of the simple content type
of a complex-type-with-simple-content, though I can see the difficulty if
its also allowed for named simple types.

(My implementation problem here is that I have three subclasses of
UserSimpleType, called UserAtomicType, UserListType, and UserUnionType, and
it seems I'm going to have to introduce a fourth, or to make the parent
class non-abstract. Or change the design entirely - I have a recurrent
problem in representing simple types whose variety is not yet known because
of late binding.)

Michael Kay


> -----Original Message-----
> From: Henry S. Thompson [mailto:ht@inf.ed.ac.uk] 
> Sent: 17 November 2006 10:00
> To: Sandy Gao
> Cc: Michael Kay; xmlschema-dev@w3.org
> Subject: Re: Deriving from xs:anySimpleType
> Hash: SHA1
> I prefer option (3), allow it.  We allow vacuous redefinition 
> of anyType, why not of anySimpleType?
> Note further that in 1.1, 3.15.1 has already changed to allow 
> for anyAtomicType. . .
> I think we just add to that paragraph, along the lines of
>   Non-restricting derivations from anySimpleType and anyAtomic type
>   are also allowed, that is, derivations involving no facets.
> and add a parallel exception to the para. Michael pointed to 
> originally, allowing for variety to be absent in cases of 
> vacuous restriction of anySimpleType.
> ht
> - --
>  Henry S. Thompson, HCRC Language Technology Group, 
> University of Edinburgh
>                      Half-time member of W3C Team
>     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 
> 131 650-4440
>             Fax: (44) 131 650-4587, e-mail: ht@inf.ed.ac.uk
>                    URL: http://www.ltg.ed.ac.uk/~ht/ [mail 
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Received on Friday, 17 November 2006 18:43:07 UTC

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