Determinig if a handler exists from code

[Doug]

Hi all,

Does anyone a way to determine if a handler has been assigned to a delegate,
at runtime? I'm converting some C# code and it tests whether or not the
handler has been assigned. Unfortuntely, VB doesn't support the technique.

Thanks,

Doug

[Herfried K. Wagner [MVP]]

* "Doug" <dl***@panthers ys.com> scripsit:

Does anyone a way to determine if a handler has been assigned to a delegate,
at runtime? I'm converting some C# code and it tests whether or not the
handler has been assigned. Unfortuntely, VB doesn't support the technique.

You don't need to test that in VB. Simply use 'RaiseEvent'.

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://dotnet.mvps.org/dotnet/faqs/>

[Doug]

Thanks for the quick response Herfried,

What I was looking for was a VB equivalent of this C# snippet. VB does
not allow testing the delegate for a handler. It assumes you want to
raise the event.

In hindsight, all it seems to do is not raise the event if no handler is
present. May not be worth the effort...

C#-------
public event QueryShowTheDra gCursorEventHan dler
QueryShowTheDra gCursor;

protected virtual void
OnQueryShowTheD ragCursor(Query ShowTheDragCurs orEventArgs e)
{
//If handler present then raise the event
if(QueryShowThe DragCursor != null)
QueryShowTheDra gCursor(this, e);

}

VB-----
Protected Overridable Sub OnQueryShowTheD ragCursor(ByVal e As
QueryShowTheDra gCursorEventArg s)
If (Not QueryShowTheDra gCursor Is Nothing) Then
RaiseEvent QueryShowTheDra gCursor(Me, e)
End If
End Sub
Thanks for your time,

Doug

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[Herfried K. Wagner [MVP]]

* Doug <an********@dev elopersdex.com> scripsit:

What I was looking for was a VB equivalent of this C# snippet. VB does
not allow testing the delegate for a handler. It assumes you want to
raise the event.

In hindsight, all it seems to do is not raise the event if no handler is
present. May not be worth the effort...
If (Not QueryShowTheDra gCursor Is Nothing) Then
RaiseEvent QueryShowTheDra gCursor(Me, e)

The 'If...Then...' is not required.

--
M S Herfried K. Wagner
M V P <URL:http://dotnet.mvps.org/>
V B <URL:http://dotnet.mvps.org/dotnet/faqs/>