REPORT  Z17_004.

CLASS counter DEFINITION.
  PUBLIC SECTION.
*    PROTECTED SECTION.
    DATA count TYPE i.
ENDCLASS.

CLASS counter2 DEFINITION INHERITING FROM counter.
  PUBLIC SECTION.
    METHODS: set IMPORTING set_value type i,
             increment,
             get EXPORTING get_value type i.
    PRIVATE SECTION.
*    PROTECTED SECTION.
*    DATA count TYPE i.
ENDCLASS.

CLASS counter2 IMPLEMENTATION.
  METHOD set.
    count = set_value.
  ENDMETHOD.
  METHOD increment.
    ADD 1 TO count.
  ENDMETHOD.
  METHOD get.
    get_value = count.
  ENDMETHOD.
ENDCLASS.

DATA : CREF1 TYPE REF TO COUNTER2,
       L_imp   TYPE I.
START-OF-SELECTION.
CREATE OBJECT CREF1.

CALL METHOD CREF1->SET( exporting set_value = 3 ).

CALL METHOD CREF1->increment.

CALL METHOD CREF1->GET( IMPORTING get_value = l_imp ).
WRITE : / 'GET METHOD :' , l_imp.