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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: overrun with bohemians?
 Rick Jelliffe: > I think we need to draw the line between different kinds of "typelessness". > > There is > * late binding (where the information needed for typing is only available > at the last minute) In my construction, I think this is the preference of most bohemians. > * reflection (where the object carries its type information around) Gah. Silly Java terminology ;-) Can we just call this "intrinsic type". i.e. something that approximates English usage? > * casting (where the language or some context forces a thing to be > treated a certain type) Hmm. This to me is just late binding with language-specific details. > * generic operations (where, rather than a thing having no type, it > is deemed to have some very generic operations, such as equality testing > only) Yes. Yes. Yes. I think this is an *essential* conformance level for XML data typing. If you put this generic power into a Turing complete language such as XSLT, then you end up with all the power of static typing, yet much more flexibility. > * dynamic typing, where a value is looked at, and the type is selected from > it according to lexical hints Yes. This should be every bit as important as static typing. Also, the hints should also be able to come from environment. > * typelessness, at an extreme where an operation occurs without any > checking on some kind of memory location or a pointer. > > The occurrences of these in XML might be > * late binding, such as in XML Schemas when you may access base > types very late Unless XPath invokes the type without your explicitly telling it to do so. Also, it seems to me that using a Schema is very early binding (i.e. during validation, which is considered a phase in parsing). Why do you say it is late? > * reflection, such as using xsi:type to figure out the type I don't understand this. I would say that reflection is more a matter of using type() in XPath 2.0. xsi-:type is a type declaration, not a reflection operator. > * casting, such as where a query treats some text as a particular type > * generic operations, pretty much what XML is without XML Schemas, > wander around trees and look a strings. Well not really. Fundamental specs such as XPath don't provide adequate tools for generic processing. We've discussed this on XML-DEV before, and have an idea what such a module might look like. Along comes XPath 2.0 which dumps 10 tons of cruft for static typing, and still not a peep for generic processing, which, as you say is "XML is without XML Schemas". Doesn't that seem queer? > * dynamic typing, such as the = operation in XSLT Which is what I say we need more of, on the same modular basis as the need for data typing. That's all. > I don't really see any typelessness at work in XML: it seems to be a property > of languages rather than data. Oh no. It is certainly a property of data. -- Uche Ogbuji Fourthought, Inc. http://uche.ogbuji.net http://4Suite.org http://fourthought.com Tour of 4Suite - http://www.xml.com/pub/a/2002/10/16/py-xml.html Proper XML Output in Python - http://www.xml.com/pub/a/2002/11/13/py-xml.html RSS for Python - http://www-106.ibm.com/developerworks/webservices/library/ws-p yth11.html Debug XSLT on the fly - http://www-106.ibm.com/developerworks/xml/library/x-deb ugxs.html 
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