ABAP Events: EVENTS, RAISE EVENT, SET HANDLER

Kategorie
ABAP-OO
Veröffentlicht
Autor
Johannes

Eventos en ABAP Object-Oriented permiten comunicacion desacoplada entre objetos. Una clase puede disparar un evento, y otras clases pueden reaccionar a el sin dependencia directa.

Sintaxis

Declaracion de evento

EVENTS <nombre_evento>
  [ EXPORTING VALUE(<parametro>) TYPE <tipo> ... ].

Disparar evento

RAISE EVENT <nombre_evento>
  [ EXPORTING <parametro> = <valor> ... ].

Definir Handler

METHODS <nombre_handler> FOR EVENT <nombre_evento> OF <clase>
  [ IMPORTING <parametro> ... ].

Registrar Handler

SET HANDLER <handler> FOR <objeto>.
SET HANDLER <handler> FOR ALL INSTANCES.

Ejemplos

1. Evento basico

CLASS zcl_button DEFINITION.
  PUBLIC SECTION.
    " Declaracion de evento
    EVENTS clicked.


    METHODS press.
ENDCLASS.


CLASS zcl_button IMPLEMENTATION.
  METHOD press.
    " Disparar el evento
    RAISE EVENT clicked.
  ENDMETHOD.
ENDCLASS.


" Clase Handler
CLASS zcl_handler DEFINITION.
  PUBLIC SECTION.
    METHODS on_button_click FOR EVENT clicked OF zcl_button.
ENDCLASS.


CLASS zcl_handler IMPLEMENTATION.
  METHOD on_button_click.
    WRITE: / 'Boton fue clickeado!'.
  ENDMETHOD.
ENDCLASS.


" Uso
DATA: lo_button  TYPE REF TO zcl_button,
      lo_handler TYPE REF TO zcl_handler.


CREATE OBJECT: lo_button, lo_handler.


" Registrar handler
SET HANDLER lo_handler->on_button_click FOR lo_button.


" Disparar evento
lo_button->press( ).  " Salida: "Boton fue clickeado!"

2. Evento con parametros

CLASS zcl_order DEFINITION.
  PUBLIC SECTION.
    EVENTS order_created
      EXPORTING VALUE(ev_order_id)    TYPE i
                VALUE(ev_customer_id) TYPE string.


    METHODS create_order
      IMPORTING iv_customer_id TYPE string
      RETURNING VALUE(rv_order_id) TYPE i.


  PRIVATE SECTION.
    DATA: mv_next_id TYPE i VALUE 1000.
ENDCLASS.


CLASS zcl_order IMPLEMENTATION.
  METHOD create_order.
    " Logica de negocio
    mv_next_id = mv_next_id + 1.
    rv_order_id = mv_next_id.


    " Disparar evento con datos
    RAISE EVENT order_created
      EXPORTING ev_order_id    = rv_order_id
                ev_customer_id = iv_customer_id.
  ENDMETHOD.
ENDCLASS.


" Handler
CLASS zcl_order_logger DEFINITION.
  PUBLIC SECTION.
    METHODS on_order_created
      FOR EVENT order_created OF zcl_order
      IMPORTING ev_order_id ev_customer_id.
ENDCLASS.


CLASS zcl_order_logger IMPLEMENTATION.
  METHOD on_order_created.
    WRITE: / 'Nuevo pedido:', ev_order_id,
             'para cliente:', ev_customer_id.
  ENDMETHOD.
ENDCLASS.

3. Multiples Handlers

" Multiples clases pueden reaccionar al mismo evento
CLASS zcl_notification_service DEFINITION.
  PUBLIC SECTION.
    METHODS on_order_created
      FOR EVENT order_created OF zcl_order
      IMPORTING ev_order_id ev_customer_id.
ENDCLASS.


CLASS zcl_inventory_service DEFINITION.
  PUBLIC SECTION.
    METHODS on_order_created
      FOR EVENT order_created OF zcl_order
      IMPORTING ev_order_id.
ENDCLASS.


" Uso
DATA: lo_order    TYPE REF TO zcl_order,
      lo_logger   TYPE REF TO zcl_order_logger,
      lo_notif    TYPE REF TO zcl_notification_service,
      lo_inventory TYPE REF TO zcl_inventory_service.


CREATE OBJECT: lo_order, lo_logger, lo_notif, lo_inventory.


" Registrar multiples handlers
SET HANDLER lo_logger->on_order_created FOR lo_order.
SET HANDLER lo_notif->on_order_created FOR lo_order.
SET HANDLER lo_inventory->on_order_created FOR lo_order.


" Un evento -> tres handlers ejecutados
lo_order->create_order( 'CUST001' ).

4. Eventos estaticos (CLASS-EVENTS)

CLASS zcl_system_monitor DEFINITION.
  PUBLIC SECTION.
    " Evento estatico - no necesita instancia
    CLASS-EVENTS system_error
      EXPORTING VALUE(ev_message) TYPE string.


    CLASS-METHODS report_error
      IMPORTING iv_message TYPE string.
ENDCLASS.


CLASS zcl_system_monitor IMPLEMENTATION.
  METHOD report_error.
    RAISE EVENT system_error
      EXPORTING ev_message = iv_message.
  ENDMETHOD.
ENDCLASS.


" Handler para evento estatico
CLASS zcl_error_logger DEFINITION.
  PUBLIC SECTION.
    METHODS on_system_error
      FOR EVENT system_error OF zcl_system_monitor
      IMPORTING ev_message.
ENDCLASS.


" Registro para eventos estaticos
DATA: lo_logger TYPE REF TO zcl_error_logger.
CREATE OBJECT lo_logger.


" Sin FOR <objeto> - porque es estatico
SET HANDLER lo_logger->on_system_error.


" Disparar
zcl_system_monitor=>report_error( 'Error critico!' ).

5. SET HANDLER FOR ALL INSTANCES

" Un handler para TODAS las instancias de una clase
DATA: lo_handler TYPE REF TO zcl_order_logger.


CREATE OBJECT lo_handler.


" Registrar para todas las instancias (existentes y futuras)
SET HANDLER lo_handler->on_order_created FOR ALL INSTANCES.


" Ahora cualquier instancia de zcl_order dispara el handler
DATA: lo_order1 TYPE REF TO zcl_order,
      lo_order2 TYPE REF TO zcl_order.


CREATE OBJECT: lo_order1, lo_order2.


lo_order1->create_order( 'CUST001' ).  " Handler se ejecuta
lo_order2->create_order( 'CUST002' ).  " Handler se ejecuta

6. Desregistrar Handler

" Registrar
SET HANDLER lo_handler->on_order_created FOR lo_order.


" Desregistrar (con ACTIVATION abap_false)
SET HANDLER lo_handler->on_order_created
  FOR lo_order
  ACTIVATION abap_false.


" Ahora el handler ya no se ejecuta
lo_order->create_order( 'CUST003' ).  " Sin reaccion

7. Patron Observer con Eventos

" Sujeto Observable
CLASS zcl_stock DEFINITION.
  PUBLIC SECTION.
    EVENTS price_changed
      EXPORTING VALUE(ev_symbol) TYPE string
                VALUE(ev_price)  TYPE p.


    METHODS set_price
      IMPORTING iv_symbol TYPE string
                iv_price  TYPE p.
ENDCLASS.


CLASS zcl_stock IMPLEMENTATION.
  METHOD set_price.
    " Actualizar precio y notificar
    RAISE EVENT price_changed
      EXPORTING ev_symbol = iv_symbol
                ev_price  = iv_price.
  ENDMETHOD.
ENDCLASS.


" Observador 1: Pantalla
CLASS zcl_stock_display DEFINITION.
  PUBLIC SECTION.
    METHODS on_price_change
      FOR EVENT price_changed OF zcl_stock
      IMPORTING ev_symbol ev_price.
ENDCLASS.


CLASS zcl_stock_display IMPLEMENTATION.
  METHOD on_price_change.
    WRITE: / 'Pantalla:', ev_symbol, ev_price.
  ENDMETHOD.
ENDCLASS.


" Observador 2: Alerta
CLASS zcl_stock_alert DEFINITION.
  PUBLIC SECTION.
    METHODS on_price_change
      FOR EVENT price_changed OF zcl_stock
      IMPORTING ev_symbol ev_price.


  PRIVATE SECTION.
    DATA: mv_threshold TYPE p VALUE 100.
ENDCLASS.


CLASS zcl_stock_alert IMPLEMENTATION.
  METHOD on_price_change.
    IF ev_price > mv_threshold.
      WRITE: / 'ALERTA:', ev_symbol, 'supera umbral!'.
    ENDIF.
  ENDMETHOD.
ENDCLASS.

8. Eventos en interfaces

INTERFACE zif_document.
  EVENTS document_saved
    EXPORTING VALUE(ev_doc_id) TYPE string.


  METHODS save.
ENDINTERFACE.


CLASS zcl_invoice DEFINITION.
  PUBLIC SECTION.
    INTERFACES zif_document.
    ALIASES document_saved FOR zif_document~document_saved.
ENDCLASS.


CLASS zcl_invoice IMPLEMENTATION.
  METHOD zif_document~save.
    " Guardar factura
    DATA(lv_doc_id) = 'INV-001'.


    " Disparar evento de interfaz
    RAISE EVENT document_saved
      EXPORTING ev_doc_id = lv_doc_id.
  ENDMETHOD.
ENDCLASS.


" Handler para interfaz
CLASS zcl_doc_handler DEFINITION.
  PUBLIC SECTION.
    METHODS on_doc_saved
      FOR EVENT document_saved OF zif_document
      IMPORTING ev_doc_id.
ENDCLASS.

9. Eventos con objeto sender

" Parametro SENDER implicito
CLASS zcl_handler DEFINITION.
  PUBLIC SECTION.
    METHODS on_clicked
      FOR EVENT clicked OF zcl_button
      IMPORTING sender.  " Objeto que disparo el evento
ENDCLASS.


CLASS zcl_handler IMPLEMENTATION.
  METHOD on_clicked.
    " Acceder al objeto disparador
    DATA(lo_button) = sender.


    " Llamar metodos del sender si es necesario
    " lo_button->get_id( ).
  ENDMETHOD.
ENDCLASS.

10. Ejemplo practico: Sistema de pedidos

" Sistema de eventos completo
CLASS zcl_order_system DEFINITION.
  PUBLIC SECTION.
    EVENTS: order_placed
              EXPORTING VALUE(ev_order) TYPE REF TO zcl_order_data,
            order_shipped
              EXPORTING VALUE(ev_order_id) TYPE string,
            order_cancelled
              EXPORTING VALUE(ev_order_id) TYPE string
                        VALUE(ev_reason)   TYPE string.


    METHODS: place_order
               IMPORTING is_data TYPE zst_order_input
               RETURNING VALUE(rv_order_id) TYPE string,
             ship_order
               IMPORTING iv_order_id TYPE string,
             cancel_order
               IMPORTING iv_order_id TYPE string
                         iv_reason   TYPE string.
ENDCLASS.


" Servicio de Email
CLASS zcl_email_service DEFINITION.
  PUBLIC SECTION.
    METHODS: constructor,
             on_order_placed FOR EVENT order_placed OF zcl_order_system
               IMPORTING ev_order,
             on_order_shipped FOR EVENT order_shipped OF zcl_order_system
               IMPORTING ev_order_id,
             on_order_cancelled FOR EVENT order_cancelled OF zcl_order_system
               IMPORTING ev_order_id ev_reason.
ENDCLASS.


CLASS zcl_email_service IMPLEMENTATION.
  METHOD constructor.
    " Auto-registro en sistema de ordenes
    DATA(lo_order_system) = zcl_order_system=>get_instance( ).


    SET HANDLER: on_order_placed FOR lo_order_system,
                 on_order_shipped FOR lo_order_system,
                 on_order_cancelled FOR lo_order_system.
  ENDMETHOD.


  METHOD on_order_placed.
    " Enviar email de confirmacion
    WRITE: / 'Email: Pedido confirmado'.
  ENDMETHOD.


  METHOD on_order_shipped.
    " Enviar email de envio
    WRITE: / 'Email: Pedido enviado', ev_order_id.
  ENDMETHOD.


  METHOD on_order_cancelled.
    " Enviar email de cancelacion
    WRITE: / 'Email: Pedido cancelado', ev_order_id, ev_reason.
  ENDMETHOD.
ENDCLASS.

Resumen

AspectoSintaxis
Declarar eventoEVENTS <nombre> EXPORTING ...
Evento estaticoCLASS-EVENTS <nombre> ...
DispararRAISE EVENT <nombre>
Definir handlerMETHODS ... FOR EVENT ... OF ...
RegistrarSET HANDLER <handler> FOR <objeto>
Todas instanciasSET HANDLER ... FOR ALL INSTANCES
DesregistrarSET HANDLER ... ACTIVATION abap_false

Notas importantes / Mejores practicas

  • Los eventos permiten desacoplamiento entre clases.
  • Usar CLASS-EVENTS para eventos que no necesitan instancia.
  • FOR ALL INSTANCES registra para todas las instancias (existentes y futuras).
  • El parametro sender da acceso al objeto disparador.
  • Los handlers se ejecutan sincronicamente en el mismo hilo.
  • Desregistrar handlers cuando el objeto ya no se necesita (evitar memory leaks).
  • Los eventos son ideales para el Patron Observer.
  • En ABAP Cloud/RAP: usar RAP Business Events en lugar de eventos de clase.