ABAP Enumerations: Type-Safe Enumerated Types

Syntax

TYPES: BEGIN OF ENUM <enum_name> [ BASE TYPE <base_type> ] [ STRUCTURE <structure_name> ],
         <value1> [ VALUE <n> ],
         <value2> [ VALUE <n> ],
         ...
       END OF ENUM <enum_name> [ STRUCTURE <structure_name> ].

Basic Principle

Enumerations define a closed set of values
Each value automatically gets an integer value (0, 1, 2, …)
Variables of enum type can only hold valid values
Compiler checking prevents invalid assignments

Examples

1. Simple Enumeration

" Define enumeration
TYPES: BEGIN OF ENUM ty_traffic_light,
         red,
         yellow,
         green,
       END OF ENUM ty_traffic_light.

" Declare variable
DATA: lv_light TYPE ty_traffic_light.

" Assign value
lv_light = red.

" Use in conditions
CASE lv_light.
  WHEN red.
    WRITE: / 'Stop!'.
  WHEN yellow.
    WRITE: / 'Caution!'.
  WHEN green.
    WRITE: / 'Go!'.
ENDCASE.

2. Comparison: Enumeration vs. Constants

" === OLD: Loose constants (error-prone) ===
CONSTANTS: c_status_new       TYPE c VALUE 'N',
           c_status_approved  TYPE c VALUE 'A',
           c_status_rejected  TYPE c VALUE 'R'.

DATA: lv_status TYPE c.
lv_status = 'X'.  " Invalid value - no compiler error!


" === NEW: Enumeration (type-safe) ===
TYPES: BEGIN OF ENUM ty_status,
         new,
         approved,
         rejected,
       END OF ENUM ty_status.

DATA: lv_status2 TYPE ty_status.
lv_status2 = approved.   " OK
" lv_status2 = 'X'.      " SYNTAX ERROR! Only enum values allowed

3. Enumeration with STRUCTURE

" With STRUCTURE for qualified access
TYPES: BEGIN OF ENUM ty_order_status STRUCTURE order_status,
         open,
         processing,
         shipped,
         delivered,
         cancelled,
       END OF ENUM ty_order_status STRUCTURE order_status.

DATA: lv_status TYPE ty_order_status.

" Qualified access via structure
lv_status = order_status-processing.

CASE lv_status.
  WHEN order_status-open.
    WRITE: / 'Order open'.
  WHEN order_status-processing.
    WRITE: / 'In processing'.
  WHEN order_status-shipped.
    WRITE: / 'Shipped'.
  WHEN order_status-delivered.
    WRITE: / 'Delivered'.
  WHEN order_status-cancelled.
    WRITE: / 'Cancelled'.
ENDCASE.

4. Explicit Values

" Default: Automatic values 0, 1, 2, ...
TYPES: BEGIN OF ENUM ty_auto,
         val_a,    " = 0
         val_b,    " = 1
         val_c,    " = 2
       END OF ENUM ty_auto.

" Assign explicit values
TYPES: BEGIN OF ENUM ty_http_status STRUCTURE http_status BASE TYPE i,
         ok            VALUE 200,
         created       VALUE 201,
         bad_request   VALUE 400,
         unauthorized  VALUE 401,
         not_found     VALUE 404,
         server_error  VALUE 500,
       END OF ENUM ty_http_status STRUCTURE http_status.

DATA: lv_http TYPE ty_http_status.
lv_http = http_status-not_found.

WRITE: / 'HTTP Status:', CONV i( lv_http ).  " 404

5. BASE TYPE

" String-based enumeration
TYPES: BEGIN OF ENUM ty_color STRUCTURE color BASE TYPE string,
         red    VALUE `#FF0000`,
         green  VALUE `#00FF00`,
         blue   VALUE `#0000FF`,
         white  VALUE `#FFFFFF`,
         black  VALUE `#000000`,
       END OF ENUM ty_color STRUCTURE color.

DATA: lv_color TYPE ty_color.
lv_color = color-blue.

" Extract value
DATA(lv_hex) = CONV string( lv_color ).
WRITE: / 'Color code:', lv_hex.  " #0000FF

6. Enumeration in Classes

CLASS lcl_order DEFINITION.
  PUBLIC SECTION.
    " Enumeration as class type
    TYPES: BEGIN OF ENUM ty_status STRUCTURE status,
             draft,
             submitted,
             approved,
             rejected,
           END OF ENUM ty_status STRUCTURE status.

    METHODS: constructor,
             set_status IMPORTING iv_status TYPE ty_status,
             get_status RETURNING VALUE(rv_status) TYPE ty_status,
             approve,
             reject.

  PRIVATE SECTION.
    DATA: mv_status TYPE ty_status.
ENDCLASS.

CLASS lcl_order IMPLEMENTATION.
  METHOD constructor.
    mv_status = status-draft.
  ENDMETHOD.

  METHOD set_status.
    mv_status = iv_status.
  ENDMETHOD.

  METHOD get_status.
    rv_status = mv_status.
  ENDMETHOD.

  METHOD approve.
    IF mv_status = status-submitted.
      mv_status = status-approved.
    ENDIF.
  ENDMETHOD.

  METHOD reject.
    IF mv_status = status-submitted.
      mv_status = status-rejected.
    ENDIF.
  ENDMETHOD.
ENDCLASS.


" Usage
DATA(lo_order) = NEW lcl_order( ).

lo_order->set_status( lcl_order=>status-submitted ).
lo_order->approve( ).

DATA(lv_current) = lo_order->get_status( ).
IF lv_current = lcl_order=>status-approved.
  WRITE: / 'Order approved'.
ENDIF.

7. Enumeration in SWITCH/COND

TYPES: BEGIN OF ENUM ty_weekday STRUCTURE weekday,
         monday,
         tuesday,
         wednesday,
         thursday,
         friday,
         saturday,
         sunday,
       END OF ENUM ty_weekday STRUCTURE weekday.

DATA: lv_day TYPE ty_weekday VALUE weekday-friday.

" With SWITCH
DATA(lv_type) = SWITCH string( lv_day
  WHEN weekday-saturday OR weekday-sunday THEN 'Weekend'
  ELSE 'Weekday'
).

" With COND
DATA(lv_message) = COND string(
  WHEN lv_day = weekday-monday THEN 'Start of week'
  WHEN lv_day = weekday-friday THEN 'Almost weekend!'
  WHEN lv_day = weekday-saturday OR lv_day = weekday-sunday THEN 'Free!'
  ELSE 'Normal day'
).

WRITE: / lv_type.     " Weekday
WRITE: / lv_message.  " Almost weekend!

8. Enumeration with VALUE

TYPES: BEGIN OF ENUM ty_priority STRUCTURE priority,
         low,
         medium,
         high,
         critical,
       END OF ENUM ty_priority STRUCTURE priority.

TYPES: BEGIN OF ty_task,
         id       TYPE i,
         name     TYPE string,
         priority TYPE ty_priority,
       END OF ty_task.

" Initialize structure with enumeration
DATA(ls_task) = VALUE ty_task(
  id       = 1
  name     = 'Important task'
  priority = priority-high
).

" Table with enumerations
DATA: lt_tasks TYPE TABLE OF ty_task.

lt_tasks = VALUE #(
  ( id = 1 name = 'Bug Fix'  priority = priority-critical )
  ( id = 2 name = 'Feature'  priority = priority-medium )
  ( id = 3 name = 'Docs'     priority = priority-low )
).

" Filter by priority
LOOP AT lt_tasks INTO DATA(ls_t) WHERE priority >= priority-high.
  WRITE: / ls_t-id, ls_t-name.
ENDLOOP.

9. Iterate Enum Values

TYPES: BEGIN OF ENUM ty_size STRUCTURE size,
         xs,
         s,
         m,
         l,
         xl,
         xxl,
       END OF ENUM ty_size STRUCTURE size.

" Loop through all values (with integer conversion)
DO.
  DATA(lv_size) = CONV ty_size( sy-index - 1 ).

  " Check if valid value (within range)
  IF lv_size > size-xxl.
    EXIT.
  ENDIF.

  WRITE: / 'Size:', lv_size.
ENDDO.

10. Enumeration in Interfaces

INTERFACE lif_document.
  TYPES: BEGIN OF ENUM ty_doc_type STRUCTURE doc_type,
           invoice,
           credit_memo,
           delivery_note,
           quotation,
         END OF ENUM ty_doc_type STRUCTURE doc_type.

  METHODS: get_type RETURNING VALUE(rv_type) TYPE ty_doc_type.
ENDINTERFACE.


CLASS lcl_invoice DEFINITION.
  PUBLIC SECTION.
    INTERFACES: lif_document.
ENDCLASS.

CLASS lcl_invoice IMPLEMENTATION.
  METHOD lif_document~get_type.
    rv_type = lif_document=>doc_type-invoice.
  ENDMETHOD.
ENDCLASS.

11. Convert Enum to String

TYPES: BEGIN OF ENUM ty_payment STRUCTURE payment,
         cash,
         credit_card,
         bank_transfer,
         paypal,
       END OF ENUM ty_payment STRUCTURE payment.

DATA: lv_payment TYPE ty_payment VALUE payment-credit_card.

" Enum name as string (Reflection)
DATA(lo_type) = CAST cl_abap_enumdescr(
  cl_abap_typedescr=>describe_by_data( lv_payment )
).

" All members with names
LOOP AT lo_type->members INTO DATA(ls_member).
  WRITE: / ls_member-name, '=', ls_member-value.
ENDLOOP.

" Output:
" CASH = 0
" CREDIT_CARD = 1
" BANK_TRANSFER = 2
" PAYPAL = 3

12. Practical Example: State Machine

CLASS lcl_document_workflow DEFINITION.
  PUBLIC SECTION.
    TYPES: BEGIN OF ENUM ty_state STRUCTURE state,
             draft,
             pending_review,
             approved,
             published,
             archived,
           END OF ENUM ty_state STRUCTURE state.

    METHODS: constructor,
             submit RETURNING VALUE(rv_success) TYPE abap_bool,
             approve RETURNING VALUE(rv_success) TYPE abap_bool,
             publish RETURNING VALUE(rv_success) TYPE abap_bool,
             archive RETURNING VALUE(rv_success) TYPE abap_bool,
             get_state RETURNING VALUE(rv_state) TYPE ty_state,
             get_available_actions RETURNING VALUE(rt_actions) TYPE string_table.

  PRIVATE SECTION.
    DATA: mv_state TYPE ty_state.
ENDCLASS.

CLASS lcl_document_workflow IMPLEMENTATION.
  METHOD constructor.
    mv_state = state-draft.
  ENDMETHOD.

  METHOD submit.
    IF mv_state = state-draft.
      mv_state = state-pending_review.
      rv_success = abap_true.
    ENDIF.
  ENDMETHOD.

  METHOD approve.
    IF mv_state = state-pending_review.
      mv_state = state-approved.
      rv_success = abap_true.
    ENDIF.
  ENDMETHOD.

  METHOD publish.
    IF mv_state = state-approved.
      mv_state = state-published.
      rv_success = abap_true.
    ENDIF.
  ENDMETHOD.

  METHOD archive.
    IF mv_state = state-published.
      mv_state = state-archived.
      rv_success = abap_true.
    ENDIF.
  ENDMETHOD.

  METHOD get_state.
    rv_state = mv_state.
  ENDMETHOD.

  METHOD get_available_actions.
    rt_actions = SWITCH #( mv_state
      WHEN state-draft          THEN VALUE #( ( `Submit` ) )
      WHEN state-pending_review THEN VALUE #( ( `Approve` ) ( `Reject` ) )
      WHEN state-approved       THEN VALUE #( ( `Publish` ) )
      WHEN state-published      THEN VALUE #( ( `Archive` ) )
      ELSE VALUE #( )
    ).
  ENDMETHOD.
ENDCLASS.

Enum vs. Domain vs. Constants

Aspect	Enumeration	Domain	Constants
Type safety	Yes (Compiler)	Yes (DDIC)	No
Scope	Local or Global	Global (DDIC)	Local or Global
Value check	Compile-time	Runtime	None
Texts	Manual	Value table	None
Use case	Modern logic	DB fields	Legacy code

Important Notes / Best Practice

Use STRUCTURE for qualified access (status-approved instead of just approved).
Enumerations are type-safe – invalid values lead to syntax errors.
BASE TYPE for non-integer-based enumerations (e.g., String).
Explicit VALUE only when needed (e.g., HTTP status codes, mapping to external values).
Enumerations replace loose constants for better maintainability.
cl_abap_enumdescr for reflection (reading names).
Combine with SWITCH and CASE for clean branching.
Enumerations can be defined in CLASS and INTERFACE.
Comparisons with =, <>, <, > are possible (based on ordinal value).
Ideal for state machines, status fields and configurable options.