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Ascertaining Object Types

This example demonstrates how the dynamic type of objects is determined at runtime.

Other versions: 7.31 | 7.40 | 7.54

Source Code

    DATA: otype1 TYPE c LENGTH 30 VALUE 'C1',
          otype2 TYPE c LENGTH 30 VALUE 'C2'.

    DATA: oref1 TYPE REF TO object,
          oref2 TYPE REF TO object.

    DATA: descr_ref1 TYPE REF TO cl_abap_typedescr,
          descr_ref2 TYPE REF TO cl_abap_typedescr.

    cl_demo_input=>add_field( CHANGING field = otype1 ).
    cl_demo_input=>request(   CHANGING field = otype2 ).

    TRY.
        otype1 = cl_abap_dyn_prg=>check_whitelist_str(
          EXPORTING
            val                      = otype1
            whitelist                =  `C1,C2` ).
        otype2 = cl_abap_dyn_prg=>check_whitelist_str(
          EXPORTING
            val                      = otype2
            whitelist                =  `C1,C2` ).
      CATCH cx_abap_not_in_whitelist.
        cl_demo_output=>display( 'Input not allowed' ).
        LEAVE PROGRAM.
    ENDTRY.

    TRY.
        CREATE OBJECT: oref1 TYPE (otype1),
                       oref2 TYPE (otype2).

      CATCH cx_sy_create_object_error.
        cl_demo_output=>display( 'Create object error!' ).
        LEAVE PROGRAM.

      CATCH cx_root.
        cl_demo_output=>display( 'Other error!' ).
        LEAVE PROGRAM.

    ENDTRY.

    descr_ref1 = cl_abap_typedescr=>describe_by_object_ref( oref1 ).
    descr_ref2 = cl_abap_typedescr=>describe_by_object_ref( oref2 ).

    TRY.
        IF descr_ref1 <> descr_ref2.
          RAISE EXCEPTION TYPE conv_exc.
        ELSE.
          oref1 = oref2.
        ENDIF.

      CATCH conv_exc.
        cl_demo_output=>display(
          `Assignment from type `   && |\n| &&
          descr_ref2->absolute_name && |\n| &&
          `to `                     && |\n| &&
          descr_ref1->absolute_name && |\n| &&
          `not allowed!` ).
    ENDTRY.

Description

This example is the counterpart for object types of the example for data types. Here the dynamic type of reference variables is determined, that is, the absolute type name of the class of the object being referenced.