ABAP Object-Oriented Programming

ABAP Objects arrived in 1999 and is now the standard way to write ABAP.

Class structure

Definition and implementation

CLASS lcl_order DEFINITION.
  PUBLIC SECTION.
    METHODS constructor IMPORTING iv_order_id TYPE vbeln.
    METHODS get_total RETURNING VALUE(rv_total) TYPE p LENGTH 8 DECIMALS 2.
    CLASS-METHODS create_from_db
      IMPORTING iv_order_id     TYPE vbeln
      RETURNING VALUE(ro_order) TYPE REF TO lcl_order.

  PRIVATE SECTION.
    DATA mv_order_id TYPE vbeln.
    DATA mt_items    TYPE ty_items.
ENDCLASS.

CLASS lcl_order IMPLEMENTATION.
  METHOD constructor.
    mv_order_id = iv_order_id.
  ENDMETHOD.
ENDCLASS.

Visibility

Section	Accessible from
PUBLIC	Anywhere
PROTECTED	The class and its subclasses
PRIVATE	The class only

Instance and static

Kind	Keyword	Access
Instance attribute	DATA	obj->attr
Static attribute	CLASS-DATA	class=>attr
Instance method	METHODS	obj->method( )
Static method	CLASS-METHODS	class=>method( )

Creating objects

DATA(lo_order) = NEW lcl_order( iv_order_id = '0000012345' ).
DATA(lv_total) = lo_order->get_total( ).
DATA(lo_new)   = lcl_order=>create_from_db( '0000012345' ).

Inheritance

Redefining a method

CLASS lcl_rush_order DEFINITION INHERITING FROM lcl_order.
  PUBLIC SECTION.
    METHODS get_total REDEFINITION.
ENDCLASS.

CLASS lcl_rush_order IMPLEMENTATION.
  METHOD get_total.
    rv_total = super->get_total( ) * '1.2'.
  ENDMETHOD.
ENDCLASS.

ABAP supports single inheritance only. To combine behaviours, use interfaces.

Interfaces

Defining and implementing

INTERFACE lif_printable.
  METHODS print.
ENDINTERFACE.

CLASS lcl_invoice DEFINITION.
  PUBLIC SECTION.
    INTERFACES lif_printable.
ENDCLASS.

CLASS lcl_invoice IMPLEMENTATION.
  METHOD lif_printable~print.
    WRITE: / 'Printing the invoice'.
  ENDMETHOD.
ENDCLASS.

DATA lo_printable TYPE REF TO lif_printable.
lo_printable = NEW lcl_invoice( ).
lo_printable->print( ).

Interfaces let unrelated classes be treated uniformly — invoices and delivery notes both handled as printable things. They also make substituting a mock object for testing straightforward.

Exception classes

Raising and catching

IF sy-subrc <> 0.
  RAISE EXCEPTION TYPE zcx_customer_not_found
    EXPORTING customer_id = iv_kunnr.
ENDIF.

TRY.
    DATA(ls_customer) = lo_service->get_customer( '0000001000' ).

  CATCH zcx_customer_not_found INTO DATA(lx_notfound).
    MESSAGE lx_notfound->get_text( ) TYPE 'E'.

  CATCH cx_root INTO DATA(lx_root).
    MESSAGE lx_root->get_text( ) TYPE 'E'.
ENDTRY.

Exception base classes

Class	Behaviour
CX_STATIC_CHECK	Must be declared and handled
CX_DYNAMIC_CHECK	Checked at runtime; no declaration needed
CX_NO_CHECK	Neither declared nor caught; for fatal errors

📖 Unfamiliar term? Look it up in the SAP glossary.