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Relationships |
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A difficult point is relationships. We already have coded out one specific case: |
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comment lines, but those have a different behavior since they do not have |
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a model element of their own... |
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- In case of generalizations, realizations and dependencies, the direction of |
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the relationship is very important (not to mention state diagrams...) |
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- Assocuations have special model elements (AssociationEnd) at the end of |
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each line. |
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Generalization, Realization, Denepency, etc. |
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If one end of a relationship is not connected, nothing should happen... |
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We should try to manage all interaction from the model elements (classifiers, |
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etc.), since the canvas sends connect signals to those items (not the item |
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which handle is about to be connected). |
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This means that we should be able to determine: |
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- on which end of the relationship we are |
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- what's on the other end of the relationship |
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- do a lookup to see if such relationship already exists |
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- create a new/assign an existing relationship to the connecting item |
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- remove the relationship on disconnect or deletion (reset on UNDO) |
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Association |
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Association is a pretty difficult case, since we are dealing with a collection |
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of objects at one (Assocation and a bunch of AssociationEnd objects). |
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At first we will only make bi-directional assocaitions (no n-ary assocaitions, |
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the ones with a 'diamond' inside). |
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If only one end is connected we do not need to do anything. |
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We should be able to determine: |
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- If an assocaition already exists between the given classes |
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- If an assocaition between classes is already drawn on the diagram (in which |
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case we should look for another existing assocaition or create a new one) |
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- |
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Note: |
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Some kinds of relations are repreesented by a line in a diagram, but have no |
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direct mapping to some model element (e.g. a comment line which connects a |
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comment to a model element). How do we determine if such a relation needs |
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to be removed or can stay? For comment lines we could check all representations |
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of the comment and see if one of the annotedElement's is in a diagram. If the |
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count is 2 or more, the relationship should remain intact. |
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