Difference beetwen set handler and set_registered_events in SAP Enjoy...

Question

I'm reading now BC412 cours and I try to understand main difference beetween registering events for SAP enjoy controls using
a) set handler
b) set_registered_events
Do ABAP service this events in other ways (I mean is ABAP service events registered via set hander in different way than registered via set_registered_events)?
When I use ALV grid I use set handler to register events for which (after this event happened) should be performed any action. It is possible to define this events using internal events table?
I reward points for every helpful clues.
Cheers, Tomek
Bonus question: Why for registering events using events table, are using ID's instead events names (like double_click) ?
Message was edited by: Tomasz Suchanek
Message was edited by: Tomasz Suchanek

Answer 1

Hello Tomasz
The ALV grid control has already most events registered meaning that the corresponding event will be fired if the user executes the appropriate action (e.g. user click on a grid cell with a hotspot -> event HOTSPOT_CLICK is fired).
In order to react on this event your application must have set an event handler for the event (e.g. you have defined a method HANDLE_HOTSPOT_CLICK and registered this event handler at your ALV grid instance:
SET HANDLER lcl_event_handler=>handle_hotspot_click FOR mo_grid.  " mo_grid is you ALV grid instance
Other controls (like tree controls) have very few (if at all) events registered. The control will not fire unregistered events, and thus, you are not able to handle these events (even if you have defined an event handler method (and used SET HANDLER... for it)).
In conclusion, registering event is a two-step-process:
(1) register events (that should be fired) at the control
(2) register event handler at the control in order to react on fired events
As said before, step (1) is already done for ALV grid controls.
How to register events at the control depends on the available method. For example, CL_COLUMN_TREE_MODEL provides method SET_REGISTERED_EVENTS having an itab (type CNTL_SIMPLE_EVENTS) for importing the events. The event IDs are defined as constants in the class (or a superclass) like EVENTID_NODE_DOUBLE_CLICK.
Regards
   Uwe