Re: xml schema
Dare Obasanjo wrote: > > In my personal opinion, an article that advises against using complex > types in W3C XML Schema cannot claim to be without bias. *In context* the admonisment seems quite reasonable to me. Essentially he is saying: "XML Schema allows you to make a distinction between types and elements but most people can get away without such a distinction and arguably the distinction is not useful anyhow. So use a subset of XML Schema that re-unifies elements and types and get on with life." Note that he never said: "don't type <xs:complexType>" because then XML Schema would really be useless. He said don't treat the element as a first-class concept. Treat it as boilerplate syntax. "Furthermore, you won't lose anything by not using complex types: if a schema can be written by using complex types, then you can always write it without complex types. To be precise, you can always write it without understanding complex types, but unfortunately you have to type <complexType> elements." * http://www.xml.com/pub/a/2001/06/06/schemasimple.html#avoid_complex "In short, a complex type is a model group, plus inheritance, minus ease of use. A complex type and a model group are similar in the sense that they are used to define content models. A complex type lacks ease of use because you can't use it from other complex types or model groups. On the other hand, model groups can be used without such restriction." "... None of these problems occur if you use model groups instead of complex types. When it comes to derivation by restriction, a general understanding isn't enough; you need a very detailed understanding of how it works." So whether he is right or wrong, he argues clearly and IMO, without any discernable bias. The article does seem a bit "rushed" and the points could have been stated more clearly. For instance he could have said: "Do not use complex types outside of element declarations." -- Paul Prescod
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