DWT event handling

[Frank Benoit]

bobef schrieb:
> 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 :)

The current code that look like this:

void handleMyEvent( Event e /+optional args follow+/, int myval ){
}

addListener( DWT.Selection, dgListener( &handleMyEvent, avalue ));

What happends, that the function dgListener does create a Listener 
class, and the handleEvent is forwareded to your supplied delegate.

What am i missing?