Re: Inheritance/defaulting of attributes

Matthew Fuchs (matt@wdi.disney.com)
Thu, 9 Oct 1997 09:37:43 -0700

On Oct 9, 10:59am, Paul Prescod wrote:
> Subject: Re: Inheritance/defaulting of attributes
> Rick Jelliffe wrote:
...
> > A push for OO constructs for element declarations actually creates
> > a new distinction between declarations and the instance: the
> > declarations would act by inheritance and magic and the document
> > acts by text replacement: or is there some meaningful extension of
> > inheritance to include instance data?
>
> My proposal from yesterday does this.
>
> <!ELEMENT animal EMPTY>
> <!ELEMENT (shark|lion) ISA animal)
>
> <!ELEMENT zoo (animal+)>
>
> <ZOO>
> <SHARK/>
> <LION/>
> </ZOO>
>

Note that you have come up with new syntax to do something which in SGML would
be handled through minimization, i.e., something like:

<!entity % animals " shark | lion ">
<!element (%animals;) - O empty>
<!element animal O O (%animals;)>
<!element zoo - - (animal+)>

The parser would then interpolate <animal> tags around each <shark> or <lion>
tag, allowing the application to understand a relationship not obvious in the
document text. (OK, so I also used parameter entities. So sue me.)

Matthew

-- 
-----------------------------------------------------
Matthew Fuchs
matt@wdi.disney.com
http://cs.nyu.edu/phd_students/fuchs
-----------------------------------------------------


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