Is this a good example of the observer pattern?

[jaberwacky]

I'm learning about various design patterns and I'm trying to squeeze them into autoitobject just for giggles.

I'm just wondering what anyone thinks of this. I might use it in scripts that manage multiple GUIs, perhaps across multiple monitors?

Example.au3

#include <AutoItObject.au3>

#include "Subject.au3"
#include "ChildObserver1.au3"
#include "ChildObserver2.au3"

OnAutoItExitRegister( "cleanup" )

Global $oError = ObjEvent("AutoIt.Error", "_ErrFunc")

_AutoItObject_Startup()

Global $Subject = Subject()

Global $Observer1 = ChildObserver1()
Global $Observer2 = ChildObserver2()

$Subject.Register( $Observer1 )
$Subject.Register( $Observer2 )

$Subject.Notify()

Func cleanup()
    $Subject.Unregister( $Observer2 )
    $Subject.Unregister( $Observer1 )

    $Observer2 = ''
    $Observer1 = ''
    $Subject = ''

    _AutoItObject_Shutdown()
EndFunc

Func _ErrFunc()
    ConsoleWrite("COM Error, ScriptLine(" & $oError.scriptline & ") : Number 0x" & Hex($oError.number, 8) & " - " & $oError.windescription & @CRLF)
EndFunc

Subject.au3

expandcollapse popup

#include-once
#include <Array.au3>

Func Subject()
    Local Const $observers[ 1 ] = [ '' ]

    Local $this = _AutoItObject_Class()

    $this.AddProperty( "List" , $elscope_private , $observers )
;~  $this.AddProperty( "List" , $elscope_readonly , $observers ) ; readonly for testing purposes

    $this.AddMethod( "Register" , "Subject_Register" )
    $this.AddMethod( "Unregister" , "Subject_Unregister" )
    $this.AddMethod( "Notify" , "Subject_Notify" )

    Return $this.Object
EndFunc

Func Subject_Register( $this , Const $observer )
    Local $observers = $this.List

    If IsObj( $observer ) Then _ArrayAdd( $observers , $observer )

    $this.List = $observers

    Return $this
EndFunc

Func Subject_Unregister( $this , Const $observer )
    Local $observers = $this.List

    Local Const $element = _ArraySearch( $observers , $observer )

    _ArrayDelete( $observers , $element )

    $this.List = $observers

    Return $this
EndFunc

Func Subject_Notify( $this )
    Local $observers = $this.List

    For $i = 1 To UBound( $observers ) - 1
        $observers[ $i ].Update()
    Next

    Return $this
EndFunc

Observer.au3

#include-once

Func Observer()
    Local $this = _AutoItObject_Class()

    $this.AddDestructor( "Observer_Dtor" )

    Return $this.Object
EndFunc

Func Observer_Dtor( $this )
    MsgBox( 0 , '' , "Dtor" )
    Return $this
EndFunc

ChildObserver1.au3

#include-once

#include "Observer.au3"

Func ChildObserver1()
    Local $this = Observer()

    _AutoItObject_AddMethod( $this , "Update" , "Child_Update1" )

    Return $this
EndFunc

Func Child_Update1( $this )
    MsgBox( 0 , "Update" , "Child1" )
    Return $this
EndFunc

ChildObserver2.au3

#include-once

#include "Observer.au3"

Func ChildObserver2()
    Local $this = Observer()

    _AutoItObject_AddMethod( $this , "Update" , "Child_Update2" )

    Return $this
EndFunc

Func Child_Update2( $this )
    MsgBox( 0 , "Update" , "Child2" )
    Return $this
EndFunc

Edited April 24, 2011 by LaCastiglione