RE: Type Derivation Problems

Thank you!  I guess I gave up too early on the nested "restriction"
idea.  Thanks again for the help!

Quinton

-----Original Message-----
From: Henry S. Thompson [mailto:ht@cogsci.ed.ac.uk]
Sent: Friday, November 16, 2001 11:47 AM
To: Quinton Zondervan
Cc: xmlschema-dev@w3.org
Subject: Re: Type Derivation Problems


qyz@clickmarks.com writes:

> I can't figure out a way to extend a type which
> has an empty content model to create a sub-type with a simple content
> model.  The problem is that the only way to declare a type with a
simple
> content model is to restrict a simple type?  So I essentially need
> multiple inheritance to do this :-(

Extension is for adding attributes or elements, you can't extend with
a simple type, not even from empty content.

This is an arbitrary decision, but one it would be difficult to
overturn, I think.

If what you want is a relatively unconstrained type from which you can 
derive many simple types, use a synonym for the simple ur type:

<xs:complexType name='PropertyType' abstract='true'>
 <xs:simpleContent>
  <xs:extension base='xs:anySimpleType'/>
 </xs:simpleContent>
</xs:complexType>

<xs:complexType name='BooleanPropertyType'>
 <xs:simpleContent>
  <xs:restriction base='PropertyType'>
   <xs:simpleType>
    <xs:restriction base='xs:boolean'/>
   </xs:simpleType>
  </xs:restriction>
 </xs:simpleContent>
</xs:complexType>

ht
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of
Edinburgh
          W3C Fellow 1999--2001, part-time member of W3C Team
     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
	    Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
		     URL: http://www.ltg.ed.ac.uk/~ht/

Received on Saturday, 17 November 2001 05:16:07 UTC