What is your favorite D feature?

[Andrey via Digitalmars-d]

UDA snippet:
> class MyView : View {
>     @ViewWidget Button okButton;
>     @ViewWidget("cancelButton") Button myButton;
>     @GroupViewWidgets Button[3] buttons;
> 
>     @OnClickListener("okButton")
>     void onOkButtonClick(Widget widget) {
>         ...
>     }
> 
>     @Shortcut("TestGroup.cancel")
>     void someShortcutAction() {
>         ...
>     }
> 
>     @OnClickListener("closeButton")
>     @OnClickListener("cancelButton")
>     void onCancelButtonClick(Widget widget) {
>         ...
>     }
> }