[Ex-plain] ZeeRex - add 'operators'?

Robert Sanderson azaroth at liverpool.ac.uk
Mon May 20 12:44:53 CEST 2002


> But a question has arrisen in my mind. How do I define how to do
> relational operators such as 'greater-than'? Do we assume always to
> use Bib-1? Or should we have another section that lists operators
> with registered, agreed to names and interpretations (starting with
> Bib-1 relation operators).

I think that agreed to names would be better, but it certainly needs to be
per index.

Something like:

<index>
  <title>
  <map>
  <operators> 
    <operator>
      <title>Greater Than</title>
      <map>
        <attr attributeSet="bib1" type="2">102</attr>
      </map>
    </operator>
  </operators>
</index>

Then you can assign names as well as attributes, titles etc. without 
adding many more tags to handle it.  

> ps: Example usage: CQL when it sees 'Age>3' can look up the 'greater-than'
> definition in the ZeeRex record to generate RPN attribute lsit correctly.

Useful.  This means we certainly need to include the full map definition 
so that we can represent them completely.

As CQL has !PROX! (or similar) we should also think about the 'extended' 
relations.

Rob


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