ABAP 面向对象之继承

CLASS counter DEFINITION.
  PUBLIC SECTION.
    METHODS: set IMPORTING value(set_value) TYPE i,
             increment,
             get EXPORTING value(get_value) TYPE i.
  PROTECTED SECTION.
    DATA count TYPE i.
ENDCLASS.

CLASS counter IMPLEMENTATION.
  METHOD set.
    count = set_value.
  ENDMETHOD.
  METHOD increment.
    ADD 1 TO count.
  ENDMETHOD.
  METHOD get.
    get_value = count.
  ENDMETHOD.
ENDCLASS.

CLASS counter_ten DEFINITION INHERITING FROM counter.
  PUBLIC SECTION.
    METHODS increment REDEFINITION.
    DATA count_ten(1) TYPE c.
ENDCLASS.

CLASS counter_ten IMPLEMENTATION.
  METHOD increment.
    DATA modulo TYPE i.
    CALL METHOD super->increment.
    WRITE / count.
    modulo = count MOD 10.
    IF modulo = 0.
      count_ten = count_ten + 1.
      WRITE count_ten.
    ENDIF.
  ENDMETHOD.
ENDCLASS.

DATA: count TYPE REF TO counter,
      number TYPE i VALUE 5.

START-OF-SELECTION.

  CREATE OBJECT count TYPE counter_ten.

  CALL METHOD count->set EXPORTING set_value = number.

  DO 20 TIMES.
    CALL METHOD count->increment.
  ENDDO.