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Re: A17: keep or drop entities?



At 03:10 PM 07/10/96 +0000, James Clark wrote:
>I am only going to address entities in the document instance in this note.

I am in agreement with most of James' points.  The one where (at the
moment) I part company is best exemplified by a particular piece of text
that Michael and I are working with heavily these days - namely the outline
of the XML spec.  In the middle, one fines the following:

<BODY>
&Intro;
&Docs;
&Elements;
&Entities;
....

It's tough to imagine how we could do collaborative authoring in Vancouver
and Chicago without this kind of facility, which certainly doesn't require
the application of an OO database, etc.; and this is quite a non-trivial
task.  Or am I missing something?

BTW, James is totally right that supporting external text entities does
increase the plumbing complexity in the parser - the one time I did this it
seemed not to break the grad-could-do-it-in-a-week barrier, but it is
outside the scope of the 5-line perl hack job.  I'm not sure I believe that
"the parser has to call into the call back into the application to get the
contents of declared entities" - when I did it, all that was done down in
the lexer (yes, the lexer had to see the dsd) - which made available to the
parser (and app) a picture of the entity tree - if they wanted it.

His points about the difficulty of selling this to HTML-heads who are used
to just jamming in a URL are good too; arguably though, the transclude &
parse semantic is one that is not currently available in HTML - so they're
going to have to learn something new anyhow... and we'll certainly support
the kind of transclude & process a la the HTML <IMG tag.


Cheers, Tim Bray
tbray@textuality.com http://www.textuality.com/ +1-604-488-1167