For VB.NET (which the OP seemed to be in), I haven't found an easy analog to C#'s "something == null" syntax.
In VB.NET 2005, you can do a Custom Event and have your own AddHandler routine, which gets stored in a delegate that you can then check...but otherwise, I don't think it can be done without Reflection. --MB -----Original Message----- From: Discussion of advanced .NET topics. [mailto:[EMAIL PROTECTED] On Behalf Of gregory young Sent: Wednesday, February 14, 2007 3:31 PM To: ADVANCED-DOTNET@DISCUSS.DEVELOP.COM Subject: Re: [ADVANCED-DOTNET] Determining if an event has been assigned a delegate... The event is seen differently from outside the class .. try this. I think you can only do this for classes that you have control over. public class Test { public event EventHandler Something; public void DoSomething() { if (Something != null) { Something(this, null); } } public void PrintListenners() { PrintListenners(Something); } static void PrintListenners(Delegate del) { foreach (Delegate d in del.GetInvocationList()) { Console.WriteLine("Method Name: {0}", d.Method); Console.WriteLine("Type Name: {0}", d.Target); } } } class Program { static void Main(string[] args) { Test t = new Test(); t.Something += new EventHandler(t_Something); t.Something += new EventHandler(t_Something2); t.PrintListenners(); } static void t_Something2(object sender, EventArgs e) { Console.Write("Something2"); } static void t_Something(object sender, EventArgs e) { Console.Write("Something"); } } Cheers, Greg On 2/14/07, Mike Andrews <[EMAIL PROTECTED]> wrote: > Thank you > > After some investigation, I cannot seem to get this to work. > > I created this method: > > private static void DisplayDelegate(Delegate obj) { > foreach (Delegate d in obj.GetInvocationList()) { > Console.WriteLine("Method Name: {0}", d.Method); > Console.WriteLine("Type Name: {0}", d.Target); > } > } > > and called the method as such: > > DisplayDelegate(cb.CheckedChanged) > > where > cb is a System.Web.UI.WebControls.CheckBox > > and the compiler tells me: > The event 'System.Web.UI.WebControls.CheckBox.CheckedChanged' can only > appear on the left hand side of += or -= > > What might I be doing incorrectly here? > Is what I want to do even possible? > > Thanks, > Mike > > > > > On 2/14/07, Phil Sayers <[EMAIL PROTECTED]> wrote: > > > > google for GetInvocationList > > that should point you in the right direction > > > > > > -----Original Message----- > > From: Discussion of advanced .NET topics. > > [mailto:[EMAIL PROTECTED] Behalf Of Mike Andrews > > Sent: Wednesday, February 14, 2007 2:52 PM > > To: ADVANCED-DOTNET@DISCUSS.DEVELOP.COM > > Subject: [ADVANCED-DOTNET] Determining if an event has been assigned a > > delegate... > > > > > > Guys, > > > > Do any of you know if it's possible to determine if an event for an object > > has been assigned a delegate? > > > > Example: > > > > Dim cb As New CheckBox() > > cb.Name = "MyCheckBox" > > AddHandler(cb.CheckChanged, AddressOf CheckChanged) > > > > ... > > > > Public Sub CheckChanged(Object sender, EventArgs e) > > ... > > End Sub > > > > Is it possible to know if cb.CheckChanged has been assigned a handler or > > not? > > > > Thanks, > > Mike > > > > =================================== > > This list is hosted by DevelopMentor(r) http://www.develop.com > > > > View archives and manage your subscription(s) at > > http://discuss.develop.com > > > > =================================== > > This list is hosted by DevelopMentor(r) http://www.develop.com > > > > View archives and manage your subscription(s) at > > http://discuss.develop.com > > > > =================================== > This list is hosted by DevelopMentor(r) http://www.develop.com > > View archives and manage your subscription(s) at http://discuss.develop.com > -- Studying for the Turing test =================================== This list is hosted by DevelopMentor(r) http://www.develop.com View archives and manage your subscription(s) at http://discuss.develop.com =================================== This list is hosted by DevelopMentor® http://www.develop.com View archives and manage your subscription(s) at http://discuss.develop.com
