[Bluej-discuss] Uses arrows in BlueJ class diagrams

[Axel Schmolitzky]

Hello BlueJers,

one of the (very) few things I don't like about BlueJ is the handling of 
the uses arrows in the class diagram of a project.

It is possible in BlueJ to "declare" a uses relation between two classes 
via the uses button. Such an arrow persists, even if there is no 
dependency in the source of the origin class of the connection. It is 
even possible to remove a connecting arrow, even though a source 
dependency exists. A "rebuild package" does not "repair" this. In 
essence this means that the uses arrows in BlueJ can become meaningless 
quite easily.

This is only a problem of the uses arrows. The inheritance arrows are 
automatically kept in sync with the source, in both directions (source 
to diagram and diagram to source), as there is always a unique direct 
mapping.

I would prefer the diagram to be an exact representation of the source, 
also with the uses arrows. This would only be possible if the uses 
button were removed, because for such an action in the diagram there is 
no exact counterpart in the source that the BlueJ system could introduce.

The crucial question is: Is there any BlueJ user out there that would 
miss this functionality? I hope not.

If the button were removed the uses arrows in the diagram could be 
enhanced: a distinction could be made between a simple dependency 
(current dashed line style) and a structural dependency (a solid line). 
The former is used if the origin class declares a parameter or local 
variable of the target class while the latter is used if the origin 
class declares an instance variable of the target class. This is a 
little closer to the UML and would help teaching UML with BlueJ.

I put this request here to see whether there is any chance for a change 
like this.

	Axel


-- 

Dr. Axel Schmolitzky                           Fon: +49 40 42883 2302
Universität Hamburg                            Fax: +49 40 42883 2303
MIN-Fakultät, Dep. Informatik     Vogt-Kölln-Str. 30, D-22527 Hamburg
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