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[platform-ui-dev] User interface code smell and update of the wiki 
Hi all,

Andrey suggested me to send a message here regarding the discussion we
started there:
https://bugs.eclipse.org/bugs/show_bug.cgi?id=510745

We are researchers in software engineering that currently work on user
interface (UI) bad coding (aka. code smell) practices.
We are studying UI listeners, in particular listeners that manage
several widgets, like the following listener we spotted in
org.eclipse.ui.workbench:

@Override
public void handleEvent(Event event) {
      if (event.widget == addResourceTypeButton) {
          promptForResourceType();
      } else if (event.widget == removeResourceTypeButton) {
          removeSelectedResourceType();
      } else if (event.widget == addEditorButton) {
          promptForEditor();
      } else if (event.widget == removeEditorButton) {
          removeSelectedEditor();
      } else if (event.widget == defaultEditorButton) {
          setSelectedEditorAsDefault();
      } else if (event.widget == resourceTypeTable) {
          fillEditorTable();
      }

      updateEnabledState();

}

In such listeners, the source widget is identified using if/switch
statements.
Thanks to empirical studies we have indications that such a practice has
a negative impact on the code quality.
We call UI listeners that control three or more widgets, Blob Listeners
(see this PDF document for more details:
https://hal.inria.fr/hal-01308625v2/document).

We submitted patches to removing Blob Listener instances from
org.eclipse.ui.workbench here:
https://bugs.eclipse.org/bugs/show_bug.cgi?id=510745


Andrey suggest me the idea of adding another section or page to the
Platform UI wiki (https://wiki.eclipse.org/User_Interface_Guidelines)
and describe the blob listener pattern there.
What do you think?


Also, we have several questions for the Eclipse's developers:

1/ Do you think that coding UI listeners that manage several widgets is
a bad coding practice (cf the exemple at the beginning of the email of
the patches)?


2/ Do you think that the threshold of three or more widgets per listener
relevant for characterising a Blob listener?


3/ Do you consider the refactored code suitable for removing Blob listeners?


4/ Do you have any idea of the reason of the presence of Blob listeners
in the code?
For example, lack of anonymous functions (aka lambdas) in Java 7 (and
previous JDKs)? Multiple developers with various experiences,
backgrounds? etc.


5/ Do you have suggestions about other bad user interface coding
practices? This can concern controllers, commands, GUIs, widgets, data
bindings, GUI testing, etc.


Cheers,
--arno



-- 
Arnaud Blouin
Associate Professor INSA Rennes, France
Inria DiverSE Team (formerly Triskell)
http://people.irisa.fr/Arnaud.Blouin/

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