REPORT ZTEST .

parameters: sp_belnr type bkpf-belnr obligatory.

*---------------------------------------------------------------------*
*       CLASS lcl_handler DEFINITION
*---------------------------------------------------------------------*
*       ........                                                      *
*---------------------------------------------------------------------*
class lcl_handler definition.
  protected section.
    methods: select_data
               importing i_belnr type bkpf-belnr
               EXCEPTIONS not_found.
  private section.
    data: at_data type table of bkpf.
    methods: write_data.
endclass.

*---------------------------------------------------------------------*
*       CLASS lcl DEFINITION
*---------------------------------------------------------------------*
*       ........                                                      *
*---------------------------------------------------------------------*
class lcl definition.
  public section.
    class-data: handler type ref to lcl_handler %_friend.
    class-methods: class_constructor.
endclass.

*---------------------------------------------------------------------*
*       CLASS lcl IMPLEMENTATION
*---------------------------------------------------------------------*
*       ........                                                      *
*---------------------------------------------------------------------*
class lcl implementation.

  method class_constructor.
    create object lcl=>handler.
  endmethod.

endclass.

*---------------------------------------------------------------------*
*       CLASS lcl_handler IMPLEMENTATION
*---------------------------------------------------------------------*
*       ........                                                      *
*---------------------------------------------------------------------*
class lcl_handler implementation.

  method select_data.
    if i_belnr is initial.
      message s600(rf) with 'Укажите №' raising not_found.
    endif.
    free: me->at_data.
    select belnr gjahr bukrs
      into corresponding fields of table me->at_data
      from bkpf
      where belnr = i_belnr.
    if not sy-subrc is initial.
    message s600(rf) with 'Документы не найдены' raising not_found.
    endif.
  endmethod.

  method write_data.
    data: ls_data type bkpf.
    loop at me->at_data
      into ls_data.
      write: / ls_data-bukrs, ls_data-gjahr, ls_data-belnr.
    endloop.
  endmethod.

endclass.

start-of-selection.

call method lcl=>handler->select_data " с другом такой вызов возможен
  exporting
    i_ebeln = sp_ebeln
  exceptions
    others = 1.
if not sy-subrc is initial.
*  message id sy-msgid type sy-msgty.
  exit.
endif.

end-of-selection.

call method lcl=>handler->write_data. " и такой тоже
free: lcl=>handler->at_data. " и на это не должен ругаться

CLASS lcl_1 DEFINITION.
  PRIVATE SECTION.
    DATA privdata.
ENDCLASS.

CLASS lcl_2 DEFINITION.
  PUBLIC SECTION.
    DATA: l_obj TYPE REF TO lcl_1 %_FRIEND.
    METHODS fill.
ENDCLASS.

CLASS lcl_2 IMPLEMENTATION.
  METHOD fill.
    CREATE OBJECT l_obj.
    l_obj->privdata = 'A'.
    WRITE: l_obj->privdata.
  ENDMETHOD.
ENDCLASS.

START-OF-SELECTION.

  DATA: obj_2 TYPE REF TO lcl_2.
  CREATE OBJECT obj_2.

  CALL METHOD obj_2->fill( ).

class lcl_1 definition.
  ...
endclass.

class lcl_2 definition friends lcl_1.
  private section.
    data: a.
endclass.

class lcl_3 definition inheriting from lcl_1.
  public section.
    data: obj type ref to lcl_2.
    methods: fill.
endclass.

class lcl_3 implementation.
  method fill.
    create object obj.
    obj->a = 'A'.
    write obj->a.
  endmethod.
endclass.

start-of-selection.
  data: obj type ref to lcl_3.
  create object obj.
  obj->fill( ).