Re: Derivation by Restriction
"Fabio Arciniegas A." <l-arcini@u...> writes: > Hi all. > During the definition of a schema for instances product of Object > serialization, I begin to wonder about the implications of derivation > by restriction in XML: Schema when used with OO apps... > > Is derivation by restriction necessary/desirable? could anyone > please explain the need behind it a bit? Is D by R a "threat" to > the conformance principle when using schema to define object > hierarchies? > > just oblique thoughts... :) comments? > > Fabio > > >  loosely put, the traditional conformance principle in OO states: If B > inherits from A, B can be used wherever A can be used. That's precisely the intention of restriction. Any element information item (EII) which is valid per a type (R) derived by restriction from a type (T) by construction contains all the required components of T. It follows that all such EIIs are valid per T. ht -- Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh W3C Fellow 1999--2001, part-time member of W3C Team 2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440 Fax: (44) 131 650-4587, e-mail: ht@c... URL: http://www.ltg.ed.ac.uk/~ht/ 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/ or CD-ROM/ISBN 981-02-3594-1 Unsubscribe by posting to majordom@i... the message unsubscribe xml-dev (or) unsubscribe xml-dev your-subscribed-email@your-subscribed-address Please note: New list subscriptions now closed in preparation for transfer to OASIS.
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