Datatype constraints in DCDs

Dean Roddey roddey at
Fri Oct 9 20:02:37 BST 1998

><AttributeDef Name="Colour" Datatype="string">
>    <ValidIf rule="Equals" value="Red"/>
>    <ValidIf rule="Equals" value="Green"/>
>    <ValidIf rule="Equals" value="Blue"/>

It looks like the consensus is definitely that the more wordy XML encoding of
the constraint information is preferable. And I'm not too stressed out about
that, since I won't be the one reading them anyway :-) But I would question the
above scheme for enumerations. There was some desire to replace the proposed
DCD enumeration mechanism, but I think the above scheme would get way wordy
just to (for instance) check that something was one of the months of the year,
one of the possible XML encodings, one of the countries of the world, etc...
I'd definitely like to have some way to get the possible values all into some
slightly less versbose chunk. Even if human convenience is not an issue,
bandwidth still remains a concern, right?

I'd almost, in the name of reuse, argue for an EnumDecl that defined such enums
for reuse by name, though someone might easily poke holes in that argument
because I've not thought it out.

Dean Roddey
Software Weenie
IBM Center for Java Technology - Silicon Valley
roddey at

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