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General Board / Re: Direction of Aggregaton?
« on: December 14, 2007, 03:04:39 am »
Hi --
Thanks for the reply. I guess it has always been me that has had it backwards, although I'm sure that tools I have used in the past have presented it thus and that much of the discussion around aggregation has spoken of it in terms of a class being "composed of" or "aggregating" another class. Moreover in component technologies like Microsoft's COM or in the C++ PIMPL idiom, where the aggregating component or class holds a pointer to its included component and forwards requests to it, the whole way of thinking about the relationship is from the point of view of the "aggregator" and not from the "aggregatee", so to speak.
Just another hazard, I guess, of the informal semantics specification style of UML (although the definition you quote -- and that in my supreme anal retentivity I went to the spec to check for myself -- is pretty clear and unambiguous). It does, however, seem to me to fly in the face of conventions around the use of aggregation. As you say, in the end it doesn't really make any difference as long as you use the tool to draw the diagram correctly; you can interpret the diagram however you like.
Thanks for the reply. I guess it has always been me that has had it backwards, although I'm sure that tools I have used in the past have presented it thus and that much of the discussion around aggregation has spoken of it in terms of a class being "composed of" or "aggregating" another class. Moreover in component technologies like Microsoft's COM or in the C++ PIMPL idiom, where the aggregating component or class holds a pointer to its included component and forwards requests to it, the whole way of thinking about the relationship is from the point of view of the "aggregator" and not from the "aggregatee", so to speak.
Just another hazard, I guess, of the informal semantics specification style of UML (although the definition you quote -- and that in my supreme anal retentivity I went to the spec to check for myself -- is pretty clear and unambiguous). It does, however, seem to me to fly in the face of conventions around the use of aggregation. As you say, in the end it doesn't really make any difference as long as you use the tool to draw the diagram correctly; you can interpret the diagram however you like.