[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Inheritance/defaulting of attributes
Matthew Fuchs wrote: > Seriously though, despite having written my share of OO (and other) code, I'd > be very leery of anything that injects semantic notions into XML. IDREF isn't a semantic notion? How about the very concept of element "types". Isn't that semantic? > Whether > something is an ISA or HASA relationship may ultimately depend on the > applications point of view. I.e., lion ISA animal, but lion also HASA > superclass, depending on whether you are in the semantics of the zoo domain or > the semantics of domain structures - and these can hopefully share the same > semantics. True, but we can benefit from subclassing at the SGML/XML level, without even considering the needs of application designers. A survey of popular DTDs would demonstrate that most re-invent the concept of subtyping in a proprietary way. This makes reading, maintaining and extending the DTDs hard and processing them in (e.g.) a GUI editor even harder (basically the subtype relationships just disappear). One of very common question on comp.text.sgml is "how do I extend DTDs" and our only answer is: "by using this hack, if the DTD designer has allowed it, or this other hack, if they took a different approach ..." Archforms are not a mechanism for extending existing DTDs, but for allowing documents to conform to multiple DTDs (including existing DTDs). I find it downright embarrasing that we have no half-way decent answer to this question. Someone posed it last month on c.t.s as: "This is so basic I must have missed something obvious in the XML spec." I wonder if he ever got an answer... > But all I really wanted to point out was that in eliminating a lot of SGML > cruft, we'd also eliminated some of the tricks people have used in the past to > finesse OO. I reject the notion that the notion of subtyping is intrinsically related to OO, but I take your point. Minmization can be used to finesse many things and XML is poorer for not having it. Still, I find it uncomfortable to use minimization to make up for restrictions in the language. Paul Prescod 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/ 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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