DWT event handling

[bobef]

Lester L. Martin II Wrote:

> Frank Benoit Wrote:
> 
> > bobef schrieb:
> > > void handleTextEvent (Event e, Composite composite, TreeItem item, TreeEditor editor,Text text, int inset ) 
> > > 
> > > This is longer to write than new class {blah blah} :)
> > 
> > No, the additional arguments make the delegate a closure. If you would 
> > write that as a anonymous class it would look like that:
> > 
> > In Java final vars are accessible for the anonymous class after the 
> > surrounding method ends:
> > 
> > final Text text = ...
> > final TreeEditor editor = ...
> > 
> > Listener l = new Listener {
> >      public void handleEvent( Event e ){
> >          // use text, editor as you want
> >      }
> > }
> > 
> > In D1, this would create crashes. The workaround is, to create explicit 
> > member variable in the anonymous class. This is really ugly and very 
> > tedious and error-prone.
> > 
> > Listener l = new class( composite, item, editor, text, inset ) Listener {
> >      Composite composite_;
> >      TreeEditor editor_;
> >      Text text_;
> >      int inset_;
> >      public this( Composite a, TreeItem b, TreeEditor c,Text d, int e ) {
> >          this.composite_ = a;
> >          this.editor_ = b;
> >          this.text_ = d;
> >          this.inset_ = e;
> >      }
> >      public void handleEvent( Event e ){
> >          // use the test_, editor_ ...
> >          // underscore to clearly separate them from
> >          // the variable used in the surounding method
> >      }
> > }
> > 
> > Now you see what is the advantage of the dgListener?
> > 
> 
> In our code we just created a class that accepted a delegate. This class inherited Listener. It defined a generic event handler  that it would use if no event delegate was passed to it. What are the advantages of this template over such a design (If you need real code will post).
> 
> Lester L.  Martin II
> 

This was basically my point too. This way seems shorter than having to write all these arguments and having to remember them :)