Re: [xsl] XPath expression that generates false plus a message?

[Michael Kay <mike@xxxxxxxxxxxx>]

> I used the XPath expression within the new XML Schema 1.1<assert>  element:
>
>      <xs:element name="meeting">
>          <xs:complexType>
>              <xs:sequence>
>                  <xs:element name="start" type="xs:time" />
>                  <xs:element name="end" type="xs:time" />
>              </xs:sequence>
>              <xs:assert test="if (xs:time(start) gt xs:time(end)) then
>                                                       true()
>                                                 else
>                                                        trace(false(), 'Hey, the meeting ends before it begins!')" />
>          </xs:complexType>
>      </xs:element>
>
> Here is a<meeting>  with bad data:
>
> <meeting>
>       <start>10:00:00</start>
>       <end>09:00:00</end>
> </meeting>

Your assertion is true if the start time is greater than the end time. 
Which is the case for your "bad" data.

(Note also that comparing times is an error-prone business: what happens 
if you have a meeting that starts at 23:00 and finishes at 01:00?)

Michael Kay
Saxonica