ABAP Keyword Documentation → ABAP − Reference → Declarations → Declaration Statements → Classes and Interfaces → Components in Classes and Interfaces → Events
EVENTS
Other versions: 7.31 | 7.40 | 7.54
Syntax
EVENTS evt [EXPORTING parameters].
Addition
Effect
Declares an instance event evt in a class or interface. The
naming conventions apply to the name evt.
Using the statement RAISE EVENT,
the instance event evt can be raised in any instance method of the same class,
or of any class that implements the interface, as well as in the instance methods of subclasses (if they are visible there).
Addition
... EXPORTING parameters
Effect
The addition EXPORTING defines the parameter interface of the event
evt. An event can only have output parameters parameters that are passed by value.
When an event handler
is declared using the addition FOR EVENT OF of the statement
METHODS or
CLASS-METHODS, the output parameters of the event are defined as the input parameters of
the event handler. The properties of the input parameters are applied from the output parameters defined in EVENTS.
As well as the output parameters defined explicitly using EXPORTING, each
instance event has an implicit output parameter, sender. This output parameter
has the type reference variable. When the event is raised using RAISE EVENT, the reference to the raising object is implicitly assigned to sender.
The static type of the input parameter sender is defined for every event
handler by the object type (class or interface) that is specified after the addition FOR
EVENT OF of the statement METHODS or CLASS-METHODS.
Note
The dynamic type of the implicit formal parameter sender is always the class of the object in which the event is raised.
Example
In the interface window, three events are declared, each with an explicit
non-optional output parameter status. The class dialog_window
implements the interface window. The interface window_handler contains
event handlers, which
import both the explicit parameters and the implicit parameter sender. The
static type of the input parameter sender is the class dialog_window.
INTERFACE window.
EVENTS: minimize EXPORTING VALUE(status) TYPE i,
maximize EXPORTING VALUE(status) TYPE i,
restore EXPORTING VALUE(status) TYPE i.
ENDINTERFACE.
CLASS dialog_window DEFINITION.
PUBLIC SECTION.
INTERFACES window.
ENDCLASS.
INTERFACE window_handler.
METHODS: minimize_window
FOR EVENT window~minimize OF dialog_window
IMPORTING status sender,
maximize_window
FOR EVENT window~maximize OF dialog_window
IMPORTING status sender,
restore
FOR EVENT window~restore OF dialog_window
IMPORTING status sender.
ENDINTERFACE.