1
Suggestions and Requests / Re: Aggregation in requirement diagram
« on: October 08, 2009, 09:49:01 pm »
Paolo has argued my point precisely!
To extend the argument, consider this. If I draw a unidirectional (that is directed) association from class A to class B (with the arrow head pointing at B), then class A will contain a reference attribute for an instance of B. Yet class B is at the target end of the association!
An aggregation is a specialised form of association in that it specifies the ownership of associated class instance. However, I would still draw the association in the direction of default communication (which is my world is always unidirectional, and only bidirectional under special circumstances and even then I tend to prefer separate associations for this to capture the intent clearly). Hence when class A is making use of class B the association is drawn from A to B (with the arrow head pointing at B). If I decide that class A will own the life of class B then the source end of that association will show the required aggregation with a black diamond.
It is not possible to do this with the aggregation connector because it always puts the diamond at the target end, even with the draw aggregations reversed setting set.
Even if other view points are valid, EA should support this view point.
Regards
Dave B.
To extend the argument, consider this. If I draw a unidirectional (that is directed) association from class A to class B (with the arrow head pointing at B), then class A will contain a reference attribute for an instance of B. Yet class B is at the target end of the association!
An aggregation is a specialised form of association in that it specifies the ownership of associated class instance. However, I would still draw the association in the direction of default communication (which is my world is always unidirectional, and only bidirectional under special circumstances and even then I tend to prefer separate associations for this to capture the intent clearly). Hence when class A is making use of class B the association is drawn from A to B (with the arrow head pointing at B). If I decide that class A will own the life of class B then the source end of that association will show the required aggregation with a black diamond.
It is not possible to do this with the aggregation connector because it always puts the diamond at the target end, even with the draw aggregations reversed setting set.
Even if other view points are valid, EA should support this view point.
Regards
Dave B.