CLASS的本地Interface实现

REPORT  z_barry_test_interface.

TYPE-POOLS abap.

INTERFACE if_add.
  METHODS add IMPORTING summand TYPE i.
ENDINTERFACE.                    "if_add

INTERFACE if_subtract.
  METHODS subtract IMPORTING subtrahend TYPE i.
ENDINTERFACE.                    "if_subtract

INTERFACE if_add_subtract.
  INTERFACES: if_add,if_subtract.
ENDINTERFACE.                    "if_add_subtract

CLASS cl_stack DEFINITION.
  PUBLIC SECTION.
    INTERFACES if_add_subtract.
    ALIASES: add FOR if_add~add,
             subtract FOR if_subtract~subtract.
    DATA amount TYPE i VALUE '100' READ-ONLY.
ENDCLASS.                    "cl_stack DEFINITION

CLASS cl_stack IMPLEMENTATION.
  METHOD if_add~add.
    amount = amount + summand.
  ENDMETHOD.                    "if_add~add
  METHOD if_subtract~subtract.
    amount = amount - subtrahend.
  ENDMETHOD.                    "if_subtract~subtract
ENDCLASS.                    "cl_stack IMPLEMENTATION

DATA: iref1 TYPE REF TO if_add,
      iref2 TYPE REF TO if_subtract,
      oref  TYPE REF TO object.
DATA: ptab TYPE abap_parmbind_tab,
      ptab_line LIKE LINE OF ptab,
      para TYPE i.
FIELD-SYMBOLS TYPE i.

START-OF-SELECTION.

  CREATE OBJECT iref1 TYPE cl_stack.
  iref1->add( '10' ).
  TRY.
      iref2 ?= iref1.
      iref2->subtract( '20' ).
    CATCH cx_sy_move_cast_error.
      MESSAGE 'Casting error' TYPE 'I'.
  ENDTRY.

  oref = iref2.
  ASSIGN oref->('AMOUNT') TO .
  CALL METHOD oref->('ADD')
    EXPORTING
      summand = '10'.
  CALL METHOD oref->('SUBTRACT')
    EXPORTING
      subtrahend = '10'.

  WRITE .