A reference is a handle to an object

A parcel tracker object has its own status. A reference variable is the handle through which the program reaches that object; assigning one reference to another does not clone the object.

Create and use an instance

CLASS lcl_tracker DEFINITION.
  PUBLIC SECTION.
    DATA status TYPE string.
ENDCLASS.
CLASS lcl_tracker IMPLEMENTATION.
ENDCLASS.

DATA(tracker) = NEW lcl_tracker( ).
tracker->status = 'Packed'.
DATA(result) = tracker->status.

NEW creates an instance and returns a reference. The arrow -> accesses an instance component through that reference. A reference can also be declared first with TYPE REF TO; before it points to an object, it is initial/unbound.

An older construction form

Classic code may declare a reference and then use CREATE OBJECT tracker. Modern code commonly uses NEW, which expresses object creation in an expression and can fit inline declarations. Choose syntax supported by the target ABAP release and code style.

Aliasing is not copying

DATA(second_reference) = tracker.
second_reference->status = 'On the way'.

Now both references reach the same object. Updating through one reference is observable through the other. If you need a separate parcel, create a second object instead of copying the reference.

Practice

Instantiate a tracker, set its status, and assign that status to result; add the output statement appropriate to the selected program context. Structural validation is not ABAP execution.

Version note: Inline declarations and constructor operators depend on release/language version. Local classes are scoped to their containing program; global class creation is a separate repository design choice.

Sources

• SAP Samples, ABAP Object Orientation: objects and references
• SAP Help Portal, ABAP Objects overview

CLASS lcl_tracker DEFINITION.
  PUBLIC SECTION.
    DATA status TYPE string.
ENDCLASS.
CLASS lcl_tracker IMPLEMENTATION.
ENDCLASS.
DATA(tracker) = NEW lcl_tracker( ).
tracker->status = 'Packed'.
DATA(result) = tracker->status.

WRITE result.

out->write( result ).