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***@panthersys.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 QueryShowTheDragCursorEventHandler
QueryShowTheDragCursor;

protected virtual void
OnQueryShowTheDragCursor(QueryShowTheDragCursorEve ntArgs e)
{
//If handler present then raise the event
if(QueryShowTheDragCursor != null)
QueryShowTheDragCursor(this, e);

}

VB-----
Protected Overridable Sub OnQueryShowTheDragCursor(ByVal e As
QueryShowTheDragCursorEventArgs)
If (Not QueryShowTheDragCursor Is Nothing) Then
RaiseEvent QueryShowTheDragCursor(Me, e)
End If
End Sub
Thanks for your time,

Doug

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[Herfried K. Wagner [MVP]]

* Doug <an********@developersdex.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 QueryShowTheDragCursor Is Nothing) Then
RaiseEvent QueryShowTheDragCursor(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/>