Multiton Example (using a singleton in WM oder EWM? What about LGNUM )?

[joachimrees1]

I think in WM or EWM, if you think "singleton" it often is not right, as we don't want

"one instance per system"
but
"one instance per LGNUM per system" -> Multiton!

Here is an example:

CLASS zcl_example DEFINITION

  PUBLIC

  FINAL

  CREATE PRIVATE.



  PUBLIC SECTION.

    CLASS-METHODS: get_instance IMPORTING iv_lgnum             TYPE /scwm/lgnum

                                RETURNING VALUE(rref_instance) TYPE REF TO zcl_example.

  PROTECTED SECTION.

  PRIVATE SECTION.

    TYPES: BEGIN OF gty_instance_buffer,

             lgnum    TYPE /scwm/lgnum,

             instance TYPE REF TO zcl_example,

           END OF gty_instance_buffer.

    CLASS-DATA: st_instance_buffer TYPE HASHED TABLE OF gty_instance_buffer WITH UNIQUE KEY lgnum.



    METHODS constructor  IMPORTING iv_lgnum TYPE /scwm/lgnum.



    DATA: mv_lgnum TYPE /scwm/lgnum.

ENDCLASS.



CLASS zcl_example IMPLEMENTATION.

  METHOD constructor.

    me->mv_lgnum = iv_lgnum.

  ENDMETHOD.

  METHOD get_instance.

    READ TABLE st_instance_buffer WITH TABLE KEY lgnum = iv_lgnum

                                  ASSIGNING FIELD-SYMBOL(<lfs_instance>).

    IF sy-subrc EQ 0.

      rref_instance = <lfs_instance>-instance.

    ELSE.

      rref_instance = NEW zcl_example( iv_lgnum = iv_lgnum ).

      INSERT VALUE #( lgnum = iv_lgnum instance = rref_instance ) INTO TABLE st_instance_buffer.

    ENDIF.

  ENDMETHOD.

ENDCLASS.