Hello Shriraam
Classes may have events which can be triggered.
Example: Class CL_GUI_ALV_GRID has events for double-clicking (DOUBLE_CLICK), hotspot (HOTSPOT_CLICK), changing the toolbar (TOOLBAR), and many more.
Class CL_GUI_ALV_GRID is somewhat special because all events are already registered meaning they are active. As soon as a user double-clicks on a row in an ALV list event DOUBLE_CLICK is triggered (or raised).
Raising an event means that the (instance of the) class tells the "outside" world that something has happened which might be of interest for "somebody".
If another class is interested in these events (i.e. wants to be "informed" as soon as an event is raised) this class has to register for the event. The ABAP command looks like this:
SET HANDLER: lcl_eventhandler=>handle_double_click FOR go_grid.
LCL_EVENTHANDLER is a so-called event handler class (you can choose any name for it yet there are some best practices).
Using the SET HANDLER command method HANDLE_DOUBLE_CLICK registers for the corresponding event DOUBLE_CLICK of the instance go_grid (again, you can choose any name for the event handler method yet there are some best practices for naming).
As soon as a user double-clicks on a row in the ALV list of instance go_grid the OO Control Framework checks for all registered (and active) event handler methods which are then executed in random order.
Thus, the flow looks like this (simplified):
[1] Build ALV list
[2] PBO: Display ALV list
[3] User double-clicks on row
[4] Execute coding of all registered (and active) event handler methods
[5] Return back to displayed ALV list (do NOT pass PAI)
...
Hope this gives you some insights into events and event handling.
Regards
Uwe
Bluesky
