Re: Sets and bags / Identity of a link



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Perdita Stevens (Perdita.Stevens@dcs.ed.ac.uk)
Wed, 24 Jan 2001 16:37:40 +0000 (GMT)


JM> Perdita, it is with great respect and great trepidation that i say you JM> have fallen into the UML habit of hacking.  Hmm, I asked for that, I suppose -- what I said about AssociationClass was only intended as a way of suggesting a separation in terms that people already understand something about, it wasn't intended as a finished proposal! I'd like some collaborators to think this all through properly with... *However*, I do think we need to work in the context of UML, or at least in the context of modelling languages, because that's where the problem is. Nobody will clap if we point out that those concepts are different in the abstract: separating them is only hard once you have to work inside something where there's a real conflict about which you want when and what the relationship should be. (They are different, but not independent!) Incidentally I had been thinking 1.4beta was more consistent than it is. In fact: 2-20 says a Link "is a tuple of Instances drawn from the corresponding Classifiers" 2-106 says an AttributeLink is "a named slot in an instance, which holds the value of an attribute" 2-108 shows a Link owning LinkEnds etc., i.e. definitely not being a tuple of Instances And I've lost it for the moment, but there's also still the old reference to whether you can identify "the" link that's relevant in an interaction diagram -- whereas of course with the static view there may not be one... It would be nice to think that these things will have been made consistent by Feb 5, but somehow... Perdita -- Dr. Perdita Stevens Division of Informatics, University of Edinburgh www.dcs.ed.ac.uk/home/pxs Fax: +44 131 667 7209


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