Events raised by collections

[Sid Price]

Hello,

I have a class of objects (Device) that are managed by another object
(Devices) with a collection class (DeviceCollecti on) inherited from
Collections.Has htable. Each of the Device objects can raise an event and I
need the managing class (Devices) to be able to catch these events.

Public Class Device

Public Event StatusChange()

.... rest of class

End Class

Public Class DeviceCollectio n

Inherits Hashtable

... rest of class

End Class

Public Class Devices

private mDevices as DeviceCollectio n

.... class

End Class

Can someone set me on the right path to a solution please,

Sid.

[Terry Olsen]

I believe this is how you would do it for a collection:

For Each c as Device in mDevices
AddHandler c.MyDeviceEvent , AddressOf MyLocalEventHan dler
Next
"Sid Price" <si*@nowhere.co mwrote in message
news:%2******** *******@TK2MSFT NGP06.phx.gbl.. .

Hello,

I have a class of objects (Device) that are managed by another object
(Devices) with a collection class (DeviceCollecti on) inherited from
Collections.Has htable. Each of the Device objects can raise an event and I
need the managing class (Devices) to be able to catch these events.

Public Class Device

Public Event StatusChange()

... rest of class

End Class

Public Class DeviceCollectio n

Inherits Hashtable

.. rest of class

End Class

Public Class Devices

private mDevices as DeviceCollectio n

... class

End Class

Can someone set me on the right path to a solution please,

Sid.

[Spam Catcher]

"Terry Olsen" <to******@hotma il.comwrote in
news:#F******** ******@TK2MSFTN GP06.phx.gbl:

I believe this is how you would do it for a collection:

For Each c as Device in mDevices
AddHandler c.MyDeviceEvent , AddressOf MyLocalEventHan dler
Next
"Sid Price" <si*@nowhere.co mwrote in message
news:%2******** *******@TK2MSFT NGP06.phx.gbl.. .

>Hello,

I have a class of objects (Device) that are managed by another object
(Devices) with a collection class (DeviceCollecti on) inherited from
Collections.Ha shtable. Each of the Device objects can raise an event
and I need the managing class (Devices) to be able to catch these
events.

Public Class Device

Public Event StatusChange()

... rest of class

End Class

You may also want to change the StatusChange event to contain a
reference to the sending element:

Public Event StatusChanged(B yval sender as Device)

That'll allow you to access the sending Device easily in the global
event handler.

If you do not want to pass references of the devices all over the place,
you can just pass parameters back to the event handler.

[Tom Shelton]

On Aug 3, 5:48 pm, "Sid Price" <s...@nowhere.c omwrote:

Hello,

I have a class of objects (Device) that are managed by another object
(Devices) with a collection class (DeviceCollecti on) inherited from
Collections.Has htable. Each of the Device objects can raise an event and I
need the managing class (Devices) to be able to catch these events.

Public Class Device

Public Event StatusChange()

... rest of class

End Class

Public Class DeviceCollectio n

Inherits Hashtable

.. rest of class

End Class

Public Class Devices

private mDevices as DeviceCollectio n

... class

End Class

Can someone set me on the right path to a solution please,

Sid.

Option Strict On
Option Explicit On

Imports System
Imports System.Collecti ons.Generic

Module Module1

Sub Main()
Dim manager As New DeviceManager
manager.AddDevi ce(New Device("First") )
manager.AddDevi ce(New Device("Second" ))
manager.AddDevi ce(New Device("Third") )
manager.AddDevi ce(New Device("Fourth" ))
Console.ReadLin e()
End Sub

Friend Class DeviceManager
Private _deviceCollecti on As DeviceCollectio n

Public Sub New()
_deviceCollecti on = New DeviceCollectio n()
AddHandler _deviceCollecti on.StatusChange d, AddressOf
StatusChangedHa ndler
End Sub

Public Sub AddDevice(ByVal d As Device)
_deviceCollecti on.Add(d)
End Sub

Private Sub StatusChangedHa ndler(ByVal sender As Object, ByVal
e As EventArgs)
Console.WriteLi ne(CType(sender , Device).Name)
End Sub
End Class

Friend Class DeviceCollectio n
Implements ICollection(Of Device)
Private _devices As New List(Of Device)

Public Event StatusChanged As EventHandler

Public Sub Add(ByVal item As Device) Implements
System.Collecti ons.Generic.ICo llection(Of Device).Add
AddHandler item.StatusChan ged, AddressOf
StatusChangedHa ndler
_devices.Add(it em)
End Sub

Public Sub Clear() Implements
System.Collecti ons.Generic.ICo llection(Of Device).Clear
For Each item As Device In _devices
RemoveHandler item.StatusChan ged, AddressOf
StatusChangedHa ndler
Next
_devices.Clear( )
End Sub

Public Function Contains(ByVal item As Device) As Boolean
Implements System.Collecti ons.Generic.ICo llection(Of Device).Contain s
Return _devices.Contai ns(item)
End Function

Public Sub CopyTo(ByVal array() As Device, ByVal arrayIndex As
Integer) Implements System.Collecti ons.Generic.ICo llection(Of
Device).CopyTo
_devices.CopyTo (array, arrayIndex)
End Sub

Public ReadOnly Property Count() As Integer Implements
System.Collecti ons.Generic.ICo llection(Of Device).Count
Get
Return _devices.Count
End Get
End Property

Public ReadOnly Property IsReadOnly() As Boolean Implements
System.Collecti ons.Generic.ICo llection(Of Device).IsReadO nly
Get
Return False
End Get
End Property

Public Function Remove(ByVal item As Device) As Boolean
Implements System.Collecti ons.Generic.ICo llection(Of Device).Remove
If _devices.Contai ns(item) Then
RemoveHandler item.StatusChan ged, AddressOf
StatusChangedHa ndler
_devices.Remove (item)
End If
End Function

Public Function GetEnumerator() As
System.Collecti ons.Generic.IEn umerator(Of Device) Implements
System.Collecti ons.Generic.IEn umerable(Of Device).GetEnum erator
Return _devices.GetEnu merator()
End Function

Public Function GetEnumerator1( ) As
System.Collecti ons.IEnumerator Implements
System.Collecti ons.IEnumerable .GetEnumerator
Return _devices.GetEnu merator()
End Function

Private Sub StatusChangedHa ndler(ByVal sender As Object, ByVal
e As EventArgs)
RaiseEvent StatusChanged(s ender, e)
End Sub
End Class

Friend Class Device
Private _name As String
Public Event StatusChanged As EventHandler
Private _timer As System.Threadin g.Timer

Public Sub New(ByVal name As String)
_name = name
_timer = New System.Threadin g.Timer(Address Of TickHandler,
Nothing, 1000, 1000)
End Sub

Public ReadOnly Property Name() As String
Get
Return _name
End Get
End Property

Private Sub TickHandler(ByV al state As Object)
RaiseEvent StatusChanged(M e, New System.EventArg s())
End Sub
End Class
End Module

HTH

--
Tom Shelton

[Sid Price]

Tom,

Thank you so much for such a complete sample, it used several techniques I
am not familiar with so it may take a while for me to study it and transfer
the approach to my application.

Again, thank you,
Sid.