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.NET Forum / Languages / VB.NET / May 2008Raising events from a class
I have a class with shared properties and methods that manages the open forms in my WinForms application, VB.NET 2005. The data contained within must persist for the lifetime of the application. When the user selects a menu item on the main form I want the method of the class to add the form's data to the internal HashTable that stores it and then raise an event in the main form that will load a dialog form. Since the class is never instantiated I don't see how I can use WithEvents to handle publish/subscribe. Any ideas as to how I can get the menu manager class to do this? Thanks Carl Carl, You can use AddHandler instead of WithEvents. Kerry Moorman > I have a class with shared properties and methods that manages the > open forms in my WinForms application, VB.NET 2005. The data contained [quoted text clipped - 10 lines] > > Carl Carl, Within the Shared class you can define Shared event and that event can be raised from your shared method. Here is an example Declare event for the shared class. Shared Event E1(byval e as System.EventArgs) within the shared method call RaiseEvent E1(argument that you need to pass) Thanks, Mayur Chauhan >I have a class with shared properties and methods that manages the > open forms in my WinForms application, VB.NET 2005. The data contained [quoted text clipped - 10 lines] > > Carl > Carl, > Within the Shared class you can define Shared event and that event [quoted text clipped - 25 lines] > > - Show quoted text - Maybe if I showed some test code the question would make more sense. I'm invoking a shared method here: MenuManager1.TestIt() This event is executing a method which some some work and raises and event here: Public Class MenuManager1 Inherits System.Object Public Shared Event Start(ByVal y As Int32) Public Shared Sub TestIt() RaiseEvent Start(123) End Sub End Class I want the MySender_Start() event handler method to fire when the RaiseEvent is invoked. The problem is that this is not happening. The testIt event just finishes executong withou firing MySender_Start() . No error occurs. Public Class MyForm Private WithEvents MySender As MenuManager1 Private Sub MySender_Start(ByVal y As Int32) Handles MySender.Start Dim x As Int32 x = 1 End Sub End Class What am I missing here? Thanks again Carl > > Carl, > > Within the Shared class you can define Shared event and that event [quoted text clipped - 68 lines] > > What am I missing here? The event handler in the form class needs to be Public, not private, since it is being invoked from a different class object. > I want the MySender_Start() event handler method to fire when the > RaiseEvent is invoked. The problem is that this is not happening. The [quoted text clipped - 16 lines] > > What am I missing here? Your missing that MySender would be an instance, not the shared class itself, and that it is Nothing, since you never create an instance. You want to handle MenuManager1.Start itself, something like this: Private Sub Form1_Load(ByVal sender As Object, _ ByVal e As System.EventArgs) Handles Me.Load AddHandler MenuManager1.Start, AddressOf MyStartHandler End Sub Private Sub MyStartHandler(ByVal y As Integer) MsgBox(y.ToString) End Sub > > I want the MySender_Start() event handler method to fire when the > > RaiseEvent is invoked. The problem is that this is not happening. The [quoted text clipped - 34 lines] > > - Show quoted text - Many thanks. And for the benefit of others here is the full working solution: Private Sub frmMain_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load AddHandler MenuManager1.Start, AddressOf MySender_Start MenuManager1.TestIt() End Sub Public Sub MySender_Start(ByVal y As Int32) Dim x As Int32 x = 1 End Sub Public Class MenuManager1 Inherits System.Object Public Shared Event Start(ByVal y As Int32) Public Shared Sub TestIt() RaiseEvent Start(123) End Sub End Class > > > I want the MySender_Start() event handler method to fire when the > > > RaiseEvent is invoked. The problem is that this is not happening. The [quoted text clipped - 65 lines] > > End Class You didn't have to change from defining the event hander with the HANDLES keyword to an ADDHANDLER statement. Either way will work, it's your own preference. Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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