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Bill la Forge wrote: > > From: John Wilson <tug@w...> > >I don't think that it's unreasonable to insist that objects > >representing a Feature, Handler or Property should either implement > >a distinct interface or subclass a distinct class. If this is so > >the Parser can tell what Feature, Handler or Property is being set > >by enquiring of the type of the object. > > Filters often implement more than one (generally all) handler > interface and then register themselves with the underlying > parser/filter for the same events requested by the overlaying > application/filter. Yes, and as written, John's proposal would require distinct handler objects for each feature, which would be bad. However, with a slight modification, it would work beautifully. Instead of using a string as a feature ID, use a type descriptor (in Java, an instance of java.lang.Class). Feature handlers would be registered by supplying the Class object that represents the feature being implemented, along with a handler object that is assignable to that type. It seems probable to me that, whatever naming scheme is chosen for features, each feature will have a special interface that handlers must implement; if that's true, and Strings are used to identify features, we will effectively have two names for each feature. And using classes shares one of the good aspects of the URI solution: it piggybacks on the DNS to provide a ready-made collision-free global namespace. The only problem I see with this proposal is that it may not translate well to other languages. One possibility is for other languages to use the name of the corresponding Java interface as a feature name; for example, "org.xml.sax.NamespaceHandler". This may not be ideal, but does not seem too onerous. ---glv xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i... Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ and on CD-ROM/ISBN 981-02-3594-1 To (un)subscribe, mailto:majordomo@i... the following message; (un)subscribe xml-dev To subscribe to the digests, mailto:majordomo@i... the following message; subscribe xml-dev-digest List coordinator, Henry Rzepa (mailto:rzepa@i...)
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