Factory Method Design Pattern

The factory method pattern is a design pattern that allows for the creation of objects without specifying the type of object that is to be created in code. A factory class contains a method that allows determination of the created type at run-time.

REPORT ZADN_SAMPLE.

*----------------------------------------------------------------------*
* -> Abstract - CLASS cl_car_base DEFINITION
*----------------------------------------------------------------------*
CLASS cl_car_base DEFINITION ABSTRACT.

  PUBLIC SECTION.

    METHODS : set_attributes IMPORTING p_color TYPE string
                                       p_year  TYPE c,

              get_cartype RETURNING value(p_cartype) TYPE string.

  PRIVATE SECTION.

    DATA : color TYPE string,
           year  TYPE c LENGTH 4.

ENDCLASS.                    "cl_car_base DEFINITION

*----------------------------------------------------------------------*
* -> Abstract - CLASS cl_car_base IMPLEMENTATION
*----------------------------------------------------------------------*
CLASS cl_car_base IMPLEMENTATION.

  METHOD set_attributes.

    me->color = p_color.
    me->year  = p_year.

  ENDMETHOD.                    "set_attributes

  METHOD get_cartype.

  ENDMETHOD.                    "get_cartype

ENDCLASS.                    "cl_car_base IMPLEMENTATION

*----------------------------------------------------------------------*
* -> Concrete - CLASS cl_vectra DEFINITION
*----------------------------------------------------------------------*
CLASS cl_vectra DEFINITION INHERITING FROM cl_car_base.

  PUBLIC SECTION.

    METHODS get_cartype REDEFINITION.

ENDCLASS.                    "cl_vectra DEFINITION

*----------------------------------------------------------------------*
* -> Concrete - CLASS cl_vectra IMPLEMENTATION
*----------------------------------------------------------------------*
CLASS cl_vectra IMPLEMENTATION.

  METHOD get_cartype.

    p_cartype = 'VECTRA'.

  ENDMETHOD.                    "get_cartype

ENDCLASS.                    "cl_vectra IMPLEMENTATION

*----------------------------------------------------------------------*
* -> Concrete - CLASS cl_agile DEFINITION
*----------------------------------------------------------------------*
CLASS cl_agile DEFINITION INHERITING FROM cl_car_base.

  PUBLIC SECTION.

    METHODS get_cartype REDEFINITION.

ENDCLASS.                    "cl_agile DEFINITION

*----------------------------------------------------------------------*
* -> Concrete - CLASS cl_agile IMPLEMENTATION
*----------------------------------------------------------------------*
CLASS cl_agile IMPLEMENTATION.

  METHOD get_cartype.

    p_cartype = 'AGILE'.

  ENDMETHOD.                    "get_cartype

ENDCLASS.                    "cl_agile IMPLEMENTATION

*----------------------------------------------------------------------*
* -> Concrete - CLASS cl_prisma DEFINITION
*----------------------------------------------------------------------*
CLASS cl_prisma DEFINITION INHERITING FROM cl_car_base.

  PUBLIC SECTION.

    METHODS get_cartype REDEFINITION.

ENDCLASS.                    "cl_prisma DEFINITION

*----------------------------------------------------------------------*
* -> Concrete - CLASS cl_prisma IMPLEMENTATION
*----------------------------------------------------------------------*
CLASS cl_prisma IMPLEMENTATION.

  METHOD get_cartype.

    p_cartype = 'PRISMA'.

  ENDMETHOD.                    "get_cartype

ENDCLASS.                    "cl_prisma IMPLEMENTATION

*----------------------------------------------------------------------*
* -> Concrete - CLASS cl_fiesta DEFINITION
*----------------------------------------------------------------------*
CLASS cl_fiesta DEFINITION INHERITING FROM cl_car_base.

  PUBLIC SECTION.

    METHODS get_cartype REDEFINITION.

ENDCLASS.                    "cl_fiesta DEFINITION

*----------------------------------------------------------------------*
* -> Concrete - CLASS cl_fiesta IMPLEMENTATION
*----------------------------------------------------------------------*
CLASS cl_fiesta IMPLEMENTATION.

  METHOD get_cartype.

    p_cartype = 'FIESTA'.

  ENDMETHOD.                    "get_cartype

ENDCLASS.                    "cl_fiesta IMPLEMENTATION

*----------------------------------------------------------------------*
* -> Concrete - CLASS cl_focus DEFINITION
*----------------------------------------------------------------------*
CLASS cl_focus DEFINITION INHERITING FROM cl_car_base.

  PUBLIC SECTION.

    METHODS get_cartype REDEFINITION.

ENDCLASS.                    "cl_focus DEFINITION

*----------------------------------------------------------------------*
* -> Concrete - CLASS cl_focus IMPLEMENTATION
*----------------------------------------------------------------------*
CLASS cl_focus IMPLEMENTATION.

  METHOD get_cartype.

    p_cartype = 'FOCUS'.

  ENDMETHOD.                    "get_cartype

ENDCLASS.                    "cl_focus IMPLEMENTATION

*----------------------------------------------------------------------*
* -> Concrete - CLASS cl_ka DEFINITION
*----------------------------------------------------------------------*
CLASS cl_ka DEFINITION INHERITING FROM cl_car_base.

  PUBLIC SECTION.

    METHODS get_cartype REDEFINITION.

ENDCLASS.                    "cl_ka DEFINITION

*----------------------------------------------------------------------*
* -> Concrete - CLASS cl_ka IMPLEMENTATION
*----------------------------------------------------------------------*
CLASS cl_ka IMPLEMENTATION.

  METHOD get_cartype.

    p_cartype = 'KA'.

  ENDMETHOD.                    "get_cartype

ENDCLASS.                    "cl_ka IMPLEMENTATION

************************************************************************
************************************************************************
*                                                                      *
*                       FACTORY CLASSES DEFINITION                     *
*                                                                      *
************************************************************************

*----------------------------------------------------------------------*
* -> Abstract - CLASS cl_car_factory DEFINITION
*----------------------------------------------------------------------*
CLASS cl_car_factory DEFINITION ABSTRACT.

  PUBLIC SECTION.

    METHODS : create_car IMPORTING p_cartype     TYPE n
                         EXPORTING p_carinstance TYPE REF TO cl_car_base.

ENDCLASS.                    "cl_car_factory DEFINITION

*----------------------------------------------------------------------*
* Abstract - CLASS cl_car_factory IMPLEMENTATION
*----------------------------------------------------------------------*
CLASS cl_car_factory IMPLEMENTATION.

  METHOD create_car.

  ENDMETHOD.                    "create_car

ENDCLASS.                    "cl_car_factory IMPLEMENTATION

*----------------------------------------------------------------------*
* -> Concrete - CLASS cl_chevrolet_factory DEFINITION
*----------------------------------------------------------------------*
CLASS cl_chevrolet_factory DEFINITION INHERITING FROM cl_car_factory.

  PUBLIC SECTION.

    METHODS : create_car REDEFINITION.

ENDCLASS.                    "cl_chevrolet_factory DEFINITION

*----------------------------------------------------------------------*
* -> Concrete - CLASS cl_chevrolet_factory IMPLEMENTATION
*----------------------------------------------------------------------*
CLASS cl_chevrolet_factory IMPLEMENTATION.

  METHOD create_car.

    CASE p_cartype.

      WHEN '100'.

        CREATE OBJECT p_carinstance TYPE cl_vectra.

      WHEN '200'.

        CREATE OBJECT p_carinstance TYPE cl_agile.

      WHEN '300'.

        CREATE OBJECT p_carinstance TYPE cl_prisma.

    ENDCASE.

  ENDMETHOD.                    "create_car

ENDCLASS.                    "cl_chevrolet_factory IMPLEMENTATION

*----------------------------------------------------------------------*
* -> Concrete - CLASS cl_ford_factory DEFINITION
*----------------------------------------------------------------------*
CLASS cl_ford_factory DEFINITION INHERITING FROM cl_car_factory.

  PUBLIC SECTION.

    METHODS : create_car REDEFINITION.

ENDCLASS.                    "cl_ford_factory DEFINITION

*----------------------------------------------------------------------*
* -> Concrete - CLASS cl_ford_factory IMPLEMENTATION
*----------------------------------------------------------------------*
CLASS cl_ford_factory IMPLEMENTATION.

  METHOD create_car.

    CASE p_cartype.

      WHEN '100'.

        CREATE OBJECT p_carinstance TYPE cl_fiesta.

      WHEN '200'.

        CREATE OBJECT p_carinstance TYPE cl_focus.

      WHEN '300'.

        CREATE OBJECT p_carinstance TYPE cl_ka.

    ENDCASE.

  ENDMETHOD.                    "create_car

ENDCLASS.                    "cl_ford_factory IMPLEMENTATION

************************************************************************
************************************************************************
*                                                                      *
*                           PROGRAM FLOW LOGIC                         *
*                                                                      *
************************************************************************

START-OF-SELECTION.

  PARAMETERS : p_type1 TYPE n LENGTH 3 OBLIGATORY DEFAULT '100',
               p_type2 TYPE n LENGTH 3 OBLIGATORY DEFAULT '100'.

  DATA : o1_chevrolet_factory TYPE REF TO cl_car_factory,
         o2_ford_factory      TYPE REF TO cl_car_factory.

  DATA : o1_car TYPE REF TO cl_car_base,
         o2_car TYPE REF TO cl_car_base.

  DATA : v_type1 TYPE string,
         v_type2 TYPE string.


  CREATE OBJECT : o1_chevrolet_factory TYPE cl_chevrolet_factory,
                  o2_ford_factory      TYPE cl_ford_factory.

  o1_chevrolet_factory->create_car( EXPORTING p_cartype     = p_type1
                                    IMPORTING p_carinstance = o1_car ).

  o2_ford_factory->create_car( EXPORTING p_cartype     = p_type2
                               IMPORTING p_carinstance = o2_car ).

  IF o1_car IS BOUND.

    o1_car->set_attributes( EXPORTING p_color = 'BLACK'
                                      p_year  = '2010' ).

    v_type1 = o1_car->get_cartype(  ).

    WRITE : / 'Car Type : ', v_type1.

    ULINE.

  ENDIF.

  IF o2_car IS BOUND.

    o2_car->set_attributes( EXPORTING p_color = 'BLACK'
                                      p_year  = '2010' ).

    v_type2 = o2_car->get_cartype(  ).

    WRITE : / 'Car Type : ', v_type2.

  ENDIF.