nullreferenceexception

I am doing a little debugging, and so I want to log the eventArgs value I have a simple line that basically does: logLine = "e.Value: " + IIf(e.Value Is Nothing, "", e.Value.ToString()) The way I understand the IIF function, if the e.Value is Nothing (null) then it should return the empty string, if not it should return the .ToString of the value. I am, however getting a NullReferenceException. This doesn't make sense to me. Any idea's? IIf is an actual function, so all arguments get evaluated. The If keyword was added to VB.NET 2008 to provide the short-circuit functionality you're expecting.

From previous experience I had been under the impression that it's perfectly legal (though perhaps not advisable) to call extension methods on a null instance. So in C#, this code compiles and runs: // code in static class static bool IsNull(this object obj) { return obj == null; } // code elsewhere object x = null; bool exists = !x.IsNull(); However, I was just putting together a little suite of example code for the other members of my development team (we just upgraded to .NET 3.5 and I've been assigned the task of getting the team up to speed on some of the new features available to us),

In a larger project I am having trouble getting a WCF service method to consume a JSON parameter. So I produced a smaller test case and the behaviour is echoed. If I debug the service I can see the parameter value is null at the service call. Fiddler confirms that the JSON is being sent and JsonLint confirms it is valid. Code below with annotations from debugging. [ServiceContract] public interface IWCFService { [OperationContract] [WebInvoke(BodyStyle = WebMessageBodyStyle.WrappedRequest, ResponseFormat = WebMessageFormat.Json, UriTemplate = "getstring")] string GetString();

using System; using System.Collections.Generic; class Parent { public Child Child { get; set; } } class Child { public List<string> Strings { get; set; } } static class Program { static void Main() { // bad object initialization var parent = new Parent() { Child = { Strings = { "hello", "world" } } }; } } The above program compiles fine, but crashes at runtime with Object reference not set to an instance of the object . If you notice in the above snippet, I have omitted new while initializing the child properties. Obviously the correct way to initialize is: var parent = new Parent() { Child =