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Re: [xml-dev] Type inheritance in XML Schema

Hi Pete,
   Thanks for the answer, and all the useful information. I really
like your idea about polymorphic usage of types. Thanks for telling me
about this.

On 9/20/07, Pete Cordell <petexmldev@tech-know-ware.com> wrote:
> As you've discovered, schema does not allow you to use xs:extension on
> xs:all.  This may change in XSD 1.1, but is something we have to live with
> for the time being.
> The easiest thing to do is change your xs:all statements to xs:sequence.  As
> you've noted, this would require the order to be fixed, but it's worth
> considering whether you really need the order to be variable.
> Another approach that would work in this case would be to use attributes to
> store the data.  In this case the order would not matter, and the semantics
> of what is allowed in terms of occurrences is very much xs:all like.
> Another observation is that, if you want your OBJECTS element to be more OO
> polymorphic like, the you could define it something like:
>    <xs:element name="OBJECTS">
>      <xs:complexType>
>          <xs:sequence>
>            <xs:element name="object" type="shape" maxOccurs="unbounded"/>
>          </xs:sequence>
>      </xs:complexType>
>    </xs:element>
> XML instances of that will look something like:
>    <object xsi:type='circle'...>...</object>
>    <object xsi:type='rectangle'...>...</object>
> etc.
> HTH,
> Pete.
> --
> =============================================
> Pete Cordell
> Codalogic
> for XML Schema to C++ data binding visit
>  http://www.codalogic.com/lmx/
> =============================================

Mukul Gandhi

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