- From: Miles Sabin <msabin@cromwellmedia.co.uk>
- Date: Thu, 15 Oct 1998 11:16:55 +0100
- To: "'Don Park'" <donpark@quake.net>, "'cowan@locke.ccil.org'" <cowan@locke.ccil.org>, "'DOM list'" <www-dom@w3.org>
Don Park wrote,
> > Document someXMLDoc = new BasicDocument();
> > Element xmlElement = someXMLDoc.createElement("FOO");
> > Element htmlLikeElement = someXMLDoc.createElement("TABLE");
> >
> > if(xmlElement instanceof HTMLElement)
> > // always false
> >
> > if(htmlLikeElement instanceof HTMLElement)
> > // always false
>
>
> In all the interface-based designs I came across, I have
> never seen a single design which relied on the 'absence'
> of an interface. Exactly what advantages are there to this
> 'guaranteed' lack of interface?
<HAIRSHIRT scratchiness="extreme">
Oops ... well, it was the end of a long day ...
What I *ought* to have written was,
Document someXMLDoc = new BasicDocument();
Element xmlElement = someXMLDoc.createElement("FOO");
Element htmlLikeElement = someXMLDoc.createElement("TABLE");
if(xmlElement instanceof HTMLElement)
// possibly false (ie. implementation dependent)
if(htmlLikeElement instanceof HTMLElement)
// possibly false (ie. implementation dependent)
In defence the best I can say is that if you can't guarantee
that an interface *is* supported you'd be well advised to
assume that it *isn't* ... unless you want to get embroiled
in lots of hard to maintain switches on type. That's a bit
lame tho' ... mea culpa ...
</HAIRSHIRT>
Cheers,
Miles
--
Miles Sabin Cromwell Media
Internet Systems Architect 5/6 Glenthorne Mews
+44 (0)181 410 2230 London, W6 0LJ
msabin@cromwellmedia.co.uk England
Received on Thursday, 15 October 1998 06:22:11 UTC