Passing Event Delegate as an argument

  • Thread starter Thread starter Kerry Jenkins
  • Start date Start date
K

Kerry Jenkins

I am having problems passing an Event Delegate as an argument to a
method that accepts a delegate argument. I get the following error
message:

'Public Event ProgressChanged(sender As Object, e As
System.EventArgs)' is an event, and cannot be called directly. Use a
'RaiseEvent' statement to raise an event.

I don't want to raise the event, but rather pass the delegate
associated with an event to another method.

Here is some sample code to demonstrate the problem:

Imports System.ComponentModel

Public Delegate Sub ProgressChangedEventHandler(ByVal sender As
Object, ByVal e As EventArgs)

Public Class BackgroundWorker
Inherits Component

Public Event ProgressChanged As ProgressChangedEventHandler

Protected Overridable Sub OnProgressChanged(ByVal progressArgs As
EventArgs)
'**** Error occurs on the following line ******
ProcessDelegate(ProgressChanged, Me, progressArgs)
End Sub

Sub ProcessDelegate(ByVal del As [Delegate], ByVal args() As
Object)
Dim temp As [Delegate] = del
If (temp Is Nothing) Then
Exit Sub
End If

Dim delegates() As [Delegate] = temp.GetInvocationList()
Dim handler As [Delegate]
For Each handler In delegates
InvokeDelegate(handler, args)
Next

End Sub

End Class

I am attempting to convert Juval Lowy's .net 1.1 BackgroundWorker
component from C# to VB. I cannot get past the error above.

Article discussing this component:
http://www.code-magazine.com/Article.aspx?quickid=0403071

Link to the C# code:
http://www.idesign.net/idesign/uploads/Background with 1.1.zip

Thank you,
Kerry Jenkins
 
Kerry,
'**** Error occurs on the following line ******
ProcessDelegate(ProgressChanged, Me, progressArgs)
Click to expand...
As the message states, you are attempting to pass the Event itself to
ProcessDelegate. You need to pass the hidden Delegate field that VB.NET
creates for you.

Try something like:
'**** Error occurs on the following line ******
ProcessDelegate(ProgressChangedEvent, Me, progressArgs)
Click to expand...

Hope this helps
Jay

Kerry Jenkins said:
I am having problems passing an Event Delegate as an argument to a
method that accepts a delegate argument. I get the following error
message:

'Public Event ProgressChanged(sender As Object, e As
System.EventArgs)' is an event, and cannot be called directly. Use a
'RaiseEvent' statement to raise an event.

I don't want to raise the event, but rather pass the delegate
associated with an event to another method.

Here is some sample code to demonstrate the problem:

Imports System.ComponentModel

Public Delegate Sub ProgressChangedEventHandler(ByVal sender As
Object, ByVal e As EventArgs)

Public Class BackgroundWorker
Inherits Component

Public Event ProgressChanged As ProgressChangedEventHandler

Protected Overridable Sub OnProgressChanged(ByVal progressArgs As
EventArgs)
'**** Error occurs on the following line ******
ProcessDelegate(ProgressChanged, Me, progressArgs)
End Sub

Sub ProcessDelegate(ByVal del As [Delegate], ByVal args() As
Object)
Dim temp As [Delegate] = del
If (temp Is Nothing) Then
Exit Sub
End If

Dim delegates() As [Delegate] = temp.GetInvocationList()
Dim handler As [Delegate]
For Each handler In delegates
InvokeDelegate(handler, args)
Next

End Sub

End Class

I am attempting to convert Juval Lowy's .net 1.1 BackgroundWorker
component from C# to VB. I cannot get past the error above.

Article discussing this component:
http://www.code-magazine.com/Article.aspx?quickid=0403071

Link to the C# code:
http://www.idesign.net/idesign/uploads/Background with 1.1.zip

Thank you,
Kerry Jenkins
Click to expand...
 
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