Re: constraints - odd question

[Rick Jelliffe <ricko@allette.com.au>]

 From: "Simon St.Laurent" <simonstl@simonstl.com>

> No, the problem is that you don't know what the element names are in
> advance.  Any elements are permitted, but there can be no duplication of
> names.  I don't think the solution you proposed deals with that, unless
> I've missed something significant in XML Schema.

Oh, I get it.  OK, then what about a variant of Ken's expression?

<pattern>
    <rule context="properties/*">
        <report test="previous-sibling::*[name(.)=name(current())]"
        >There should not be duplicate properties</report>
    </rule>
</pattern>

I made it previous-sibling because then the error is reported at the
subsequent
occurrence rather than at the first one. A different way to do it might be

<pattern>
    <rule context="properties/*">
        <assert test="count(../*[name(.)=name(current())])=1"
        >There should not be duplicate properties</report>
    </rule>
</pattern>

but you would get a repeated message for the original and the
duplicate and involve twice the comparisons as the former.

Cheers
Rick Jelliffe