DWT event handling

[BLS]

Bill Baxter schrieb:
> BLS wrote:
>> Frank Benoit schrieb:
>>> I added the template function Bill suggested once to the 
>>> dwt.widgets.Listener module.
>>>
>>> http://www.dsource.org/projects/dwt-linux/browser/dwt/widgets/Listener.d?rev=243%3A84629474b5ec 
>>>
>>>
>>> You can see that in action in this snippet
>>> http://www.dsource.org/projects/dwt-samples/browser/snippets/treeeditor/Snippet111.d?rev=85%3Afa286c85e7b8 
>>>
>>>
>>> See lines: 102..106
>>>
>>> Thanks Bill for the snippets and for this cool template function 
>>> suggestion.
>>>
>>> Frank
>>
>> Hi Frank, thanks for the update !
>>
>> I still try to figure out how this code could fit ...
>>
>> template MessageMap(Mappings ...) {
>>   void addListener(uint uID) {
>>      foreach(mapping; Mappings) {
>>        if(mapping.matches(uID)) // DWTxxxx
>>          mapping.executeAction();
>>      }
>>   }
>> }
>>
>> //maybe we need template specialisation here ???
>>
>>
>> struct OnClose(alias fn) {
>>   alias fn executeAction;
>>   static bool matches(uint uid) { return uid == 5; }
>> }
>>
>> struct OnRange(uint a, uint b, alias fn) {
>>   alias fn executeAction;
>>   static bool matches(uint uid) { return uid >= a && uid <= b; }
>> }
>>
>>
>> class Foo {
>>   void foo() {
>>     writefln("foo called");
>>   }
>>   void bar() {
>>     writefln("bar called");
>>   }
>>
>>   mixin MessageMap!(
>>     OnClose!(foo),
>>     OnRange!(1, 3, bar)
>>   );
>>
>> }
>>
>> void main() {
>>   auto f = new Foo;
>>   f.addListener(5);
>>   f.addListener(2);
>> }
>>
>> At least it looks simpler (to me) Ideas ? Bjoern
> 
> I don't get it.  What's 5?
> 
> --bb

Hi Bill,

Well it's just a short sample. The 5 represents a DWT.xxxx value f.e. 
DWT.FocusOut

the class Foo expands to :

class Foo {
   void foo() {
     writefln("foo called");
   }
   void bar() {
     writefln("bar called");
   }

   void addListener(uint uID) {    //"BEGIN_MSG_MAP" <vbg>
      foreach(mapping; Mappings) { //loops 2 times -> see Mixin
        if(mapping.matches(uID))   //just like "if (uID == DWT.FocusOut)"
          mapping.executeAction(); //call delegate respect. alias
      }
   }
}

The slightly modified MessageMap :

mixin MessageMap!(
      OnFocusOut!(foo),   /+ DWT.FocusOut  calls foo() method +/
      OnRange!(1, 3, bar)
    );

HTH

Bjoern