[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Structured attributes
Why not just extend the content model? In addition to selection and sequence, we could have 'unique & unordered'. Then we could deprecate attributes all together! (To say nothing about having a far far richer content model.) Bill ----- Original Message ----- From: Henry S. Thompson <ht@c...> To: XML Developers' list <xml-dev@x...> Sent: Thursday, March 02, 2000 5:40 PM Subject: Structured attributes > [A moment's thought will lead to realisation that this is displacement > activity on the part of the XML Schema: Structures editor, who > certainly has better things to do, but I need to get this off my > chest.] > > Why not structured attributes in XML? _Why_ structured attributes? > Well, we all know the comparison between elements and attributes as > they stand: > > Elements Attributes > ordered unordered > non-unique unique > structured unstructured > > There are a lot of contexts in which the first two properties of > attributes are desireable, but the third is a serious constraint. > > Here's a design sketch for adding structured attributes: > > 1) Reserve a family of hitherto unusable names as the names of > structured attributes: On balnace I favour names with an initial > full-stop (.), but there are arguments in favour of using an initial > colon (:) instead; > > 2) Use element syntax, at the beginning of all element content, with > the following restrictions: > 2a) No attributes on structured attributes; > 2b) Contents is either all structured attributes or all text; > 2c) Order doesn't matter; > 2d) Uniqueness of names among sibling structured _and_, for children of > elements, vanilla old-style attributes. > > Example: > > <person age='49'> > <.name> > <.first>Henry</.first> > <.last>Thompson</.last> > <.middle>Swift</.middle> > </.name> > <children otherParent='p33'> > . . . > </children> > </person> > > The constraints above are equivalent to allowing 'attribute' children > to the 'attribute' element in XML Schema, along with making the > attribute name uniqueness constraint cumulative: > > <element name='person'> > <complexType> > <attribute name='age' type='integer'/> > <attribute name='name'> > <attribute name='first'/> > <attribute name='middle/> > <attribute name='last/> > </attribute> > <element name='children'>...</children> > </complexType> > </element> > > Back to my day job :-) > > 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/ > > *************************************************************************** > This is xml-dev, the mailing list for XML developers. > To unsubscribe, mailto:majordomo@x...&BODY=unsubscribe%20xml-dev > List archives are available at http://xml.org/archives/xml-dev/ > *************************************************************************** > *************************************************************************** This is xml-dev, the mailing list for XML developers. To unsubscribe, mailto:majordomo@x...&BODY=unsubscribe%20xml-dev List archives are available at http://xml.org/archives/xml-dev/ ***************************************************************************
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