事件

*&---------------------------------------------------------------------*
*& Report  ZTEST20131106_2
*&
*&---------------------------------------------------------------------*
*&
*&关于事件的实例
*&---------------------------------------------------------------------*

REPORT  ztest20131106_2.
*----------------------------------------------------------------------*
*       CLASS vehicle DEFINITION
*----------------------------------------------------------------------*
*
*----------------------------------------------------------------------*
CLASS vehicle DEFINITION INHERITING FROM object.  "定义类vehicle，这边是继承基类object.
  PUBLIC SECTION.
    EVENTS:too_fast.        "定义事件too_fast
    METHODS:accelerate,
            show_speed.
  PROTECTED SECTION.
    DATA speed TYPE i.
ENDCLASS.                    "vehicle DEFINITION
*----------------------------------------------------------------------*
*       CLASS vehicle IMPLEMENTATION
*----------------------------------------------------------------------*
*
*----------------------------------------------------------------------*
CLASS vehicle IMPLEMENTATION. "方法的实现
  METHOD accelerate.
    speed = speed + 1.  
    IF speed > 5.
      RAISE EVENT too_fast. " 在方法accelerate中触发事件too_fast,静态事件需要通过静态方法中触发
      speed = 5.

    ENDIF.
  ENDMETHOD.                    "accelerate
  METHOD show_speed.
    WRITE: / 'Speed:',speed.
  ENDMETHOD.                    "show_speed
ENDCLASS.                    "vehicle IMPLEMENTATION
*----------------------------------------------------------------------*
*       CLASS handler DEFINITION
*----------------------------------------------------------------------*
*
*----------------------------------------------------------------------*
CLASS handler DEFINITION.          "定义类handler
  PUBLIC SECTION.
    METHODS handle_excess "在handler类下定义事件too_fast的处理方法handle_excess ，FOR EVENT too_fast OF vehicle说明事件是在vehicle类下的
    FOR EVENT too_fast OF vehicle.
ENDCLASS.                    "handler DEFINITION
*----------------------------------------------------------------------*
*       CLASS handler IMPLEMENTATION
*----------------------------------------------------------------------*
*
*----------------------------------------------------------------------*
CLASS handler IMPLEMENTATION. "方法的实现
  METHOD handle_excess.
    WRITE: / 'Speed can not be too fast..'.
*          speed = 10.
  ENDMETHOD.                    "handle_excess
ENDCLASS.                    "handler IMPLEMENTATION

DATA: o_vehicle TYPE REF TO vehicle, "定义类的引用
      o_handle TYPE REF TO handler.

START-OF-SELECTION.
  CREATE OBJECT:o_vehicle,o_handle. "创建类得实例
  SET HANDLER o_handle->handle_excess FOR ALL INSTANCES.  "注册事件处理方法，这边FOR ALL INSTANCES是为处理器注册所有可以触发该事件的实例，如

果是for o_vehicle表示指定注册到o_vehicle下的事件。如果是静态事件则不需要for附加项
  DO 11 TIMES.
    CALL METHOD o_vehicle->accelerate.
    CALL METHOD o_vehicle->show_speed.

  ENDDO.