ABAP Object-Oriented Programming

引用:翱翔云天

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介绍abap object,从最基础的开始,循序渐进,慢慢掌握。

从一个最简单的例子讲起,尽量把object语句都能够涉及到。这个例子我们建了一个类,里面有相应的属性以及方法。

问题假设:有一个对象actor,对其名字进行操作,包括first name和last name,通过constructor进行初始化,利用方法ToString显示最终结果。

ABAP Object-Oriented Programming

REPORT ZBOBO_OO_001 .

*-----------------Class definition------------------------*

*Syntax

* CLASS cl DEFINITION [PUBLIC][INHERITING FROM super]

* [ABSTRACT][FINAL]

* [CREATE {PUBLIC|PROCTECTED|PRIVATE}]

* [[GLOBAL] FRIENDS [class][ifac]].

* [PUBLIC SECTION].

* This section defines the public visibility area of

* class,all components in this area can be addressed

* from outside the class, and it's subclass,and within

* the class itself.

* [PRIVATE SECTION].

* The components in this area can be addressed only in

* this class itself.

* [PROTECTED SECTION].

* The components in this area can be addressed in this

* class itself and the subclass of the class.

* ENDCLASS.

*-----------------Class definition------------------------*

ClASS LCL_ACTOR DEFINITION.

PUBLIC SECTION.

*----------------Methods definition-----------------------*

*Syntax

* General method

* METHODS meth [ABSTRACT|FINAL]

* [IMPORTING {parameter} [PREFERRED PARAMETER p]]

* [EXPORTING {parameter}]

* [CHANGING {parameter}]

* [{RAISING|EXCEPTIONS} {exc}].

* Functional method

* METHODS meth [ABSTRACT|FINAL]

* [IMPORTING {parameter} [PREFERRED PARAMETER p]]

* RETURNING VALUE(v) {TYPE ...}|{LIKE ...}

* [{RAISING|EXCEPTIONS} {exc}].

*----------------Methods definition-----------------------*

METHODS:

* Initialize the first name and last name

CONSTRUCTOR

IMPORTING SN TYPE STRING,

* Get first name

GETNAME

RETURNING VALUE(NA) TYPE STRING,

* Set first name

SETNAME

IMPORTING N TYPE STRING,

* Get last name

GETSTAGENAME

RETURNING VALUE(STN) TYPE STRING,

* Set last name

SETSTAGENAME

IMPORTING SN TYPE STRING,

* Show result

TOSTRING

RETURNING VALUE(STR) TYPE STRING.

PRIVATE SECTION.

DATA:

NAME TYPE STRING, "First name

STAGENAME TYPE STRING. "Last name

ENDCLASS.

*-----------------Class implementation-------------------*

*Syntax

* CLASS c1 IMPLEMENTATION.

* ...

* METHOD ...

* ...

* ENDMETHOD.

* ...

* ENDCLASS.

*-----------------Class implementation-------------------*

CLASS LCL_ACTOR IMPLEMENTATION.

METHOD CONSTRUCTOR.

NAME = '<NONE>'.

STAGENAME = SN.

ENDMETHOD.

METHOD GETNAME.

NA = NAME.

ENDMETHOD.

METHOD SETNAME.

NAME = N.

ENDMETHOD.

METHOD GETSTAGENAME.

STN = STAGENAME.

ENDMETHOD.

METHOD SETSTAGENAME.

STAGENAME = SN.

ENDMETHOD.

METHOD TOSTRING.

DATA: L1(20) TYPE C,

L2(20) TYPE C.

*---The below two statement is the same---*

* CALL METHOD GETSTAGENAME

* RECEIVING STN = L1.

COMPUTE L1 = ME->GETSTAGENAME( ).

*---The below two statement is the same---*

CALL METHOD GETNAME

RECEIVING NA = L2.

CONCATENATE 'First name is:'

L1

',and last name is:'

L2

INTO STR.

ENDMETHOD.

ENDCLASS.

*-----------------Main program-------------------*

DATA: OREF TYPE REF TO LCL_ACTOR.

DATA: INT TYPE STRING,

1ST TYPE STRING,

LST TYPE STRING,

RESULT TYPE STRING.

START-OF-SELECTION.

INT = 'XU BOBO'.

1ST = 'JAME'.

LST = 'GREEN'.

* Initialize

CREATE OBJECT OREF

EXPORTING SN = INT.

CALL METHOD OREF->TOSTRING

RECEIVING STR = RESULT.

WRITE: / RESULT.

* Set last name

CALL METHOD OREF->SETNAME

EXPORTING N = 1ST.

CALL METHOD OREF->TOSTRING

RECEIVING STR = RESULT.

WRITE: / RESULT.

* Set fist name

CALL METHOD OREF->SETSTAGENAME

EXPORTING SN = LST.

CALL METHOD OREF->TOSTRING

RECEIVING STR = RESULT.

WRITE: / RESULT.

Basic methods declaration and implementation

REPORT zbobo_oo_002 .

*-----------------Description------------------------*

*Basic methods declaration and implementation

*-----------------Description------------------------*

* Class declarations

CLASS attributes_and_methods DEFINITION.

PUBLIC SECTION.

CLASS-DATA object_static TYPE i.

METHODS:

set_object_value

IMPORTING value(i_object_value) TYPE i,

get_object_value

EXPORTING value(e_object_value) TYPE i,

show_result.

PRIVATE SECTION.

DATA object_value TYPE i.

CLASS-DATA object_count TYPE i.

ENDCLASS.

*Class implementations

CLASS attributes_and_methods IMPLEMENTATION.

METHOD set_object_value.

object_value = i_object_value.

ENDMETHOD.

METHOD get_object_value.

e_object_value = object_value.

object_static = object_value.

ENDMETHOD.

METHOD show_result.

CALL METHOD me->get_object_value

IMPORTING e_object_value = object_count.

WRITE: / object_count.

ENDMETHOD.

ENDCLASS.

DATA val TYPE i.

DATA oref TYPE REF TO attributes_and_methods.

START-OF-SELECTION.

CREATE OBJECT oref.

val = 10.

CALL METHOD oref->set_object_value

EXPORTING i_object_value = val.

CALL METHOD oref->show_result.

* The static attribute of class can be accessed directly

* via => symbol

WRITE: attributes_and_methods=>object_static.

Example of self-reference

REPORT zbobo_oo_003 .

*-----------------Description------------------------*

* Example of self-reference

*-----------------Description------------------------*

*Class declaration

CLASS client DEFINITION.

PUBLIC SECTION.

DATA name(10) TYPE c VALUE 'Master' READ-ONLY.

METHODS create_server.

ENDCLASS.

*---------------------------------------------------------------------*

* CLASS server DEFINITION

*---------------------------------------------------------------------*

* ........ *

*---------------------------------------------------------------------*

CLASS server DEFINITION.

PUBLIC SECTION.

METHODS acknowledge

IMPORTING creator TYPE REF TO client.

PRIVATE SECTION.

DATA name(10) TYPE c VALUE 'servant'.

ENDCLASS.

*Class implementation

CLASS client IMPLEMENTATION.

METHOD create_server.

DATA server_ref TYPE REF TO server.

CREATE OBJECT server_ref.

CALL METHOD server_ref->acknowledge

EXPORTING creator = me.

ENDMETHOD.

ENDCLASS.

*---------------------------------------------------------------------*

* CLASS server IMPLEMENTATION

*---------------------------------------------------------------------*

* ........ *

*---------------------------------------------------------------------*

CLASS server IMPLEMENTATION.

METHOD acknowledge.

DATA name TYPE string.

name = creator->name.

WRITE: me->name, 'created by', name.

ENDMETHOD.

ENDCLASS.

*Global data

DATA client_ref TYPE REF TO client.

*Processing blocks

START-OF-SELECTION.

CREATE OBJECT client_ref.

CALL METHOD client_ref->create_server.

Dynamic method call

REPORT zbobo_oo_004 .

*-----------------Description------------------------*

* Dynamic method call

*-----------------Description------------------------*

*For dynamic call, using system object

CLASS cl_abap_objectdescr DEFINITION LOAD.

*Class declaration

CLASS table_content DEFINITION.

PUBLIC SECTION.

TYPES:

BEGIN OF tr_vbeln,

sign(1),

option(2),

low TYPE vbeln_va,

high TYPE vbeln_va,

END OF tr_vbeln.

TYPES:

it_rang TYPE TABLE OF tr_vbeln.

METHODS:

get_vbak IMPORTING i_vbeln TYPE it_rang,

get_vbap IMPORTING i_vbeln TYPE it_rang.

PRIVATE SECTION.

DATA:

wa_vbak TYPE vbak,

it_vbak TYPE TABLE OF vbak,

wa_vbap TYPE vbap,

it_vbap TYPE TABLE OF vbap.

DATA:

tbname TYPE string.

METHODS show_result

IMPORTING tb_name TYPE string.

ENDCLASS.

*Class implementation

CLASS table_content IMPLEMENTATION.

METHOD get_vbak.

SELECT * FROM vbak INTO TABLE it_vbak

WHERE vbeln IN i_vbeln.

tbname = 'VBAK'.

CALL METHOD show_result

EXPORTING tb_name = tbname.

ENDMETHOD.

METHOD get_vbap.

SELECT * FROM vbap INTO TABLE it_vbap

WHERE vbeln IN i_vbeln.

tbname = 'VBAP'.

CALL METHOD show_result

EXPORTING tb_name = tbname.

ENDMETHOD.

METHOD show_result.

CASE tb_name.

WHEN 'VBAK'.

LOOP AT it_vbak INTO wa_vbak.

WRITE: / wa_vbak-vbeln.

ENDLOOP.

WHEN 'VBAP'.

LOOP AT it_vbap INTO wa_vbap.

WRITE: / wa_vbap-vbeln, wa_vbap-posnr.

ENDLOOP.

ENDCASE.

ENDMETHOD.

ENDCLASS.

DATA:

oref TYPE REF TO table_content,

dv TYPE vbeln_va.

* A new way for dynamic call in ABAP OO

DATA:

ptab TYPE abap_parmbind_tab,

ptab_line TYPE abap_parmbind.

PARAMETERS:

t_name(10) TYPE c.

SELECT-OPTIONS:

p_vbeln FOR dv.

START-OF-SELECTION.

CREATE OBJECT oref.

CONCATENATE 'GET_' t_name INTO t_name.

* First way for dynamic call, just like our function call or form call

CATCH SYSTEM-EXCEPTIONS dyn_call_meth_not_found = 4.

CALL METHOD oref->(t_name)

EXPORTING i_vbeln = p_vbeln[].

ENDCATCH.

IF sy-subrc = 4.

WRITE: 'Wrong method name!'.

ENDIF.

* Second way for dynamic call, it is special in ABAP OO

ptab_line-name = 'I_VBELN'.

ptab_line-kind = cl_abap_objectdescr=>exporting.

GET REFERENCE OF p_vbeln[] INTO ptab_line-value.

* ptab_line-value = 'P_VBELN[]'.

INSERT ptab_line INTO TABLE ptab.

WRITE: / 'New dynamic call in ABAP OO:'.

CALL METHOD oref->(t_name) PARAMETER-TABLE ptab.

Widening cast

REPORT zbobo_oo_005 .

*-----------------Description------------------------*

* Widening cast

*-----------------Description------------------------*

*Class declaration

CLASS vehicle DEFINITION.

ENDCLASS.

*---------------------------------------------------------------------*

* CLASS plane DEFINITION

*---------------------------------------------------------------------*

* ........ *

*---------------------------------------------------------------------*

CLASS plane DEFINITION INHERITING FROM vehicle.

ENDCLASS.

*---------------------------------------------------------------------*

* CLASS ship DEFINITION

*---------------------------------------------------------------------*

* ........ *

*---------------------------------------------------------------------*

CLASS ship DEFINITION INHERITING FROM vehicle.

ENDCLASS.

*---------------------------------------------------------------------*

* CLASS vehicle_handler DEFINITION

*---------------------------------------------------------------------*

* ........ *

*---------------------------------------------------------------------*

CLASS vehicle_handler DEFINITION.

PUBLIC SECTION.

METHODS handle_vehicle

IMPORTING i_ref TYPE REF TO object.

ENDCLASS.

*class implementation

CLASS vehicle_handler IMPLEMENTATION.

METHOD handle_vehicle.

DATA:

vehicle_ref TYPE REF TO vehicle,

plane_ref TYPE REF TO plane,

ship_ref TYPE REF TO ship.

CATCH SYSTEM-EXCEPTIONS move_cast_error = 4.

vehicle_ref ?= i_ref.

ENDCATCH.

IF sy-subrc = 0.

WRITE / 'WOrking with vehicle'.

ELSE.

WRITE / 'this is not a vehicle'.

EXIT.

ENDIF.

CATCH SYSTEM-EXCEPTIONS move_cast_error = 4.

plane_ref ?= i_ref.

ENDCATCH.

IF sy-subrc = 0.

WRITE / 'WOrking with plane'.

ENDIF.

CATCH SYSTEM-EXCEPTIONS move_cast_error = 4.

ship_ref ?= i_ref.

ENDCATCH.

IF sy-subrc = 0.

WRITE / 'WOrking with ship'.

ENDIF.

ENDMETHOD.

ENDCLASS.

DATA:

handler TYPE REF TO vehicle_handler,

vehicle_1 TYPE REF TO vehicle,

vehicle_2 LIKE vehicle_1.

START-OF-SELECTION.

CREATE OBJECT:

handler,

vehicle_1 TYPE plane,

vehicle_2 TYPE ship.

CALL METHOD:

handler->handle_vehicle

EXPORTING i_ref = handler,

handler->handle_vehicle

EXPORTING i_ref = vehicle_1,

handler->handle_vehicle

EXPORTING i_ref = vehicle_2.

Example of polymorphism through inheritance

REPORT zbobo_oo_006 .

*-----------------Description------------------------*

* Example of polymorphism through inheritance

*-----------------Description------------------------*

*Class declaration

CLASS ship DEFINITION ABSTRACT.

PUBLIC SECTION.

METHODS:

get_max_range ABSTRACT

RETURNING value(r_range) TYPE f,

get_name

RETURNING value(r_name) TYPE string.

PROTECTED SECTION.

DATA name TYPE string.

ENDCLASS.

*---------------------------------------------------------------------*

* CLASS motorship DEFINITION

*---------------------------------------------------------------------*

* ........ *

*---------------------------------------------------------------------*

CLASS motorship DEFINITION INHERITING FROM ship.

PUBLIC SECTION.

METHODS:

constructor IMPORTING

value(i_name) TYPE string

value(i_fuel_consumption) TYPE f

value(i_fuel_amount) TYPE f,

get_max_range REDEFINITION.

PROTECTED SECTION.

DATA:

fuel_consumption TYPE f,

fuel_amount TYPE f.

ENDCLASS.

*---------------------------------------------------------------------*

* CLASS sailingship DEFINITION

*---------------------------------------------------------------------*

* ........ *

*---------------------------------------------------------------------*

CLASS sailingship DEFINITION INHERITING FROM ship.

PUBLIC SECTION.

METHODS: constructor IMPORTING

value(i_name) TYPE string

value(i_range_per_wind_speed) TYPE f

value(i_wind_speed) TYPE f

value(i_wind_duration) TYPE f,

get_max_range REDEFINITION.

PROTECTED SECTION.

DATA: range_per_wind_speed TYPE f,

wind_speed TYPE f,

wind_duration TYPE f.

ENDCLASS.

*Class implementation

CLASS ship IMPLEMENTATION.

METHOD get_name.

r_name = name.

ENDMETHOD.

ENDCLASS.

*---------------------------------------------------------------------*

* CLASS motorship IMPLEMENTATION

*---------------------------------------------------------------------*

* ........ *

*---------------------------------------------------------------------*

CLASS motorship IMPLEMENTATION.

METHOD constructor.

name = i_name.

fuel_consumption = i_fuel_consumption.

fuel_amount = i_fuel_amount.

ENDMETHOD.

METHOD get_max_range.

r_range = fuel_amount / fuel_consumption.

ENDMETHOD.

ENDCLASS.

*---------------------------------------------------------------------*

* CLASS sailingship IMPLEMENTATION

*---------------------------------------------------------------------*

* ........ *

*---------------------------------------------------------------------*

CLASS sailingship IMPLEMENTATION.

METHOD constructor.

name = i_name.

range_per_wind_speed = i_range_per_wind_speed.

wind_speed = i_wind_speed.

wind_duration = i_wind_duration.

ENDMETHOD.

METHOD get_max_range.

r_range = wind_speed /

range_per_wind_speed * wind_duration.

ENDMETHOD.

ENDCLASS.

*Global data

DATA:

o_ship TYPE REF TO ship,

ship_tab TYPE TABLE OF REF TO ship,

name TYPE string,

range TYPE f.

START-OF-SELECTION.

CREATE OBJECT o_ship TYPE motorship

EXPORTING i_name = 'Motor Ship Wanda'

i_fuel_consumption = '0.2'

i_fuel_amount = 80.

APPEND o_ship TO ship_tab.

CREATE OBJECT o_ship TYPE sailingship

EXPORTING i_name = 'Sailing Ship Black Magic'

i_range_per_wind_speed = 25

i_wind_speed = 60

i_wind_duration = 5.

APPEND o_ship TO ship_tab.

LOOP AT ship_tab INTO o_ship.

name = o_ship->get_name( ).

range = o_ship->get_max_range( ).

WRITE: / 'Range of', name,'is',

range EXPONENT 0 DECIMALS 2,'Miles'.

ENDLOOP.

Narrowing cast for interface reference

REPORT zbobo_oo_007 .

*-----------------Description------------------------*

* Narrowing cast for interface reference

*-----------------Description------------------------*

*Interfaces

INTERFACE i1.

METHODS meth.

ENDINTERFACE.

*---------------------------------------------------------------------*

* INTERFACE i2

*---------------------------------------------------------------------*

* ........ *

*---------------------------------------------------------------------*

INTERFACE i2.

INTERFACES i1.

METHODS meth.

ENDINTERFACE.

*Class declaration

CLASS c1 DEFINITION.

PUBLIC SECTION.

INTERFACES i2.

ENDCLASS.

*Class implementation

CLASS c1 IMPLEMENTATION.

METHOD i1~meth.

WRITE: / 'Method of interface i1'.

ENDMETHOD.

METHOD i2~meth.

WRITE: / 'Method of interface i2'.

ENDMETHOD.

ENDCLASS.

DATA:

iref1 TYPE REF TO i1,

iref2 TYPE REF TO i2.

START-OF-SELECTION.

* Narrowing cast part

CREATE OBJECT iref2 TYPE c1.

* Narrowing cast part

* Narrowing cast part

iref1 = iref2.

* Narrowing cast part

CALL METHOD iref1->meth.

CALL METHOD iref2->i1~meth.

* Same as below because of narrowing cast

CALL METHOD iref2->meth.

Interface reference widening cast

REPORT zbobo_oo_008 .

*-----------------Description------------------------*

* Interface reference widening cast

*-----------------Description------------------------*

*Interface declaration

INTERFACE object_status.

METHODS write_status.

ENDINTERFACE.

*---------------------------------------------------------------------*

* INTERFACE object_movement

*---------------------------------------------------------------------*

* ........ *

*---------------------------------------------------------------------*

INTERFACE object_movement.

METHODS accelerate.

ENDINTERFACE.

*Class declaration

CLASS vehicle DEFINITION.

PUBLIC SECTION.

INTERFACES:

object_status,

object_movement.

PROTECTED SECTION.

DATA speed TYPE i.

ENDCLASS.

*Class implementation

CLASS vehicle IMPLEMENTATION.

METHOD object_movement~accelerate.

speed = speed + 1.

ENDMETHOD.

METHOD object_status~write_status.

WRITE: / 'Speed', speed.

ENDMETHOD.

ENDCLASS.

DATA:

movement_ref TYPE REF TO object_movement,

status_ref TYPE REF TO object_status.

START-OF-SELECTION.

* Narrowing cast

CREATE OBJECT movement_ref TYPE vehicle.

CALL METHOD movement_ref->accelerate.

* Widening cast

status_ref ?= movement_ref.

CALL METHOD status_ref->write_status.

Polymorphism through interfaces

REPORT zbobo_oo_009 .

*-----------------Description------------------------*

* polymorphism through interfaces

*-----------------Description------------------------*

*Interfaces delaration

INTERFACE object_status.

METHODS write_status.

ENDINTERFACE.

*Class delaration

CLASS window DEFINITION.

PUBLIC SECTION.

METHODS open_close.

INTERFACES object_status.

PROTECTED SECTION.

DATA status_flag(1) TYPE c.

ENDCLASS.

*---------------------------------------------------------------------*

* CLASS vehicle DEFINITION

*---------------------------------------------------------------------*

* ........ *

*---------------------------------------------------------------------*

CLASS vehicle DEFINITION.

PUBLIC SECTION.

INTERFACES object_status.

METHODS accelerate.

PROTECTED SECTION.

DATA speed TYPE i.

ENDCLASS.

*---------------------------------------------------------------------*

* CLASS window IMPLEMENTATION

*---------------------------------------------------------------------*

* ........ *

*---------------------------------------------------------------------*

CLASS window IMPLEMENTATION.

METHOD open_close.

IF status_flag = ''.

status_flag = 'X'.

ELSE.

status_flag = ''.

ENDIF.

ENDMETHOD.

METHOD object_status~write_status.

IF status_flag = ''.

WRITE: / 'Window is closed'.

ELSE.

WRITE: / 'Window is open'.

ENDIF.

ENDMETHOD.

ENDCLASS.

*---------------------------------------------------------------------*

* CLASS vehicle IMPLEMENTATION

*---------------------------------------------------------------------*

* ........ *

*---------------------------------------------------------------------*

CLASS vehicle IMPLEMENTATION.

METHOD accelerate.

speed = speed + 1.

ENDMETHOD.

METHOD object_status~write_status.

WRITE: / 'Speed', speed.

ENDMETHOD.

ENDCLASS.

DATA:

vehicle_ref TYPE REF TO vehicle,

window_ref TYPE REF TO window,

status_tab TYPE TABLE OF REF TO object_status.

FIELD-SYMBOLS <status> TYPE REF TO object_status.

START-OF-SELECTION.

CREATE OBJECT vehicle_ref.

CALL METHOD vehicle_ref->accelerate.

APPEND vehicle_ref TO status_tab.

CREATE OBJECT window_ref.

CALL METHOD window_ref->open_close.

APPEND window_ref TO status_tab.

LOOP AT status_tab ASSIGNING <status>.

CALL METHOD <status>->write_status.

ENDLOOP.

Definition and triggering of events and handle events

REPORT zbobo_oo_010 .

*-----------------Description------------------------*

* Definition and triggering of events

* And handle events

*-----------------Description------------------------*

*Class declaration

CLASS pilot DEFINITION.

PUBLIC SECTION.

METHODS call_flight_attendant.

EVENTS call_button_pressed.

ENDCLASS.

*---------------------------------------------------------------------*

* CLASS passenger DEFINITION

*---------------------------------------------------------------------*

* ........ *

*---------------------------------------------------------------------*

CLASS passenger DEFINITION.

PUBLIC SECTION.

METHODS: constructor

IMPORTING i_seatnumber TYPE i,

call_for_help.

EVENTS call_button_pressed

EXPORTING value(e_seatnumber) TYPE i.

PROTECTED SECTION.

DATA seatnumber TYPE i.

ENDCLASS.

*---------------------------------------------------------------------*

* CLASS flight_attendant DEFINITION

*---------------------------------------------------------------------*

* ........ *

*---------------------------------------------------------------------*

CLASS flight_attendant DEFINITION.

PUBLIC SECTION.

METHODS: constructor

IMPORTING i_id TYPE string,

help_the_pilot FOR EVENT

call_button_pressed OF pilot,

help_the_passenger FOR EVENT

call_button_pressed OF passenger

IMPORTING e_seatnumber.

PROTECTED SECTION.

DATA id TYPE string.

ENDCLASS.

*Class implementation

CLASS pilot IMPLEMENTATION.

METHOD call_flight_attendant.

RAISE EVENT call_button_pressed.

ENDMETHOD.

ENDCLASS.

*---------------------------------------------------------------------*

* CLASS passenger IMPLEMENTATION

*---------------------------------------------------------------------*

* ........ *

*---------------------------------------------------------------------*

CLASS passenger IMPLEMENTATION.

METHOD constructor.

seatnumber = i_seatnumber.

ENDMETHOD.

METHOD call_for_help.

RAISE EVENT call_button_pressed

EXPORTING e_seatnumber = seatnumber.

ENDMETHOD.

ENDCLASS.

*---------------------------------------------------------------------*

* CLASS flight_attendant IMPLEMENTATION

*---------------------------------------------------------------------*

* ........ *

*---------------------------------------------------------------------*

CLASS flight_attendant IMPLEMENTATION.

METHOD constructor.

id = i_id.

ENDMETHOD.

METHOD help_the_pilot.

WRITE: / id, 'helps pilot'.

ENDMETHOD.

METHOD help_the_passenger.

WRITE: / id, 'helps passenger on seat',e_seatnumber.

ENDMETHOD.

ENDCLASS.

DATA: pilot TYPE REF TO pilot,

passenger_1 TYPE REF TO passenger,

passenger_2 TYPE REF TO passenger.

DATA: purser TYPE REF TO flight_attendant,

stewardess TYPE REF TO flight_attendant.

START-OF-SELECTION.

CREATE OBJECT:

pilot,

passenger_1 EXPORTING i_seatnumber = 11,

passenger_2 EXPORTING i_seatnumber = 17,

purser EXPORTING i_id = 'Purser',

stewardess EXPORTING i_id = 'Stewardess'.

SET HANDLER:

purser->help_the_pilot FOR pilot,

stewardess->help_the_passenger FOR ALL INSTANCES.

CALL METHOD:

pilot->call_flight_attendant,

passenger_1->call_for_help,

passenger_2->call_for_help.

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