You learn something new every day

I encountered something today in C# that I’ve never seen before and it caught me off guard. In looking at the WSE 2.0 samples to understand how the transport mechanisms have changed, I came across the following in StockService:

Uri uri = new Uri("soap.tcp://" + System.Net.Dns.GetHostName() + "/StockService");

SoapReceivers.Add( uri, typeof(StockServiceRequestReceiver) );

You’re probably wondering, “What’s the big deal, Hambone?” On the surface, this doesn’t seem so odd until you look at the method signature for SoapReceivers.Add:

public static void Add(EndpointReference, SoapReceiver);

public static void Add(EndpointReference, Type);

public static void Add(EndpointReference, SoapReceiver, bool);

public static void Add(EndpointReference, Type, bool);

Nowhere does SoapReceiers.Add take a System.Uri, yet that’s what’s being passed in above. What makes this possible is an implicit operator on EndpointReference that takes a Uri:

public static implicit operator EndpointReference(Uri uri)

{

      return new EndpointRefernece(uri);

}

I hate to admit that I was responsible for conducting a number of classes internally on C# and a) never brought this up and b) it was never mentioned. In fact, this is the first time I’ve actually seen this in use. I’m interested in your feedback … how many of you use this C# feature in your development, and to what effect?

Comments

• Anonymous
  December 14, 2003
  Yowch! That's not really typesafe. Maybe C# isn't as typesafe as it claims. Operator overloading shouldn't allow that type of side effect.
• Anonymous
  December 15, 2003
  On the surface, it may appear that it's not really typesafe, but it still is. It's not taking a Uri and casting it to an EndpointRefernece, rather it's instantiating a new EndpointReference from a Uri. The end result is that when you access the object you're always accessing it as the type you've told the compiler.
  
  It's the same as saying:
  
  EndpointReference e = new EndpointReference(uri);
  SoapReceivers.Add(e, typeof(StockServiceRequestReceiver));
  
  It just looks really funky and I personally wouldn't advocate anyone actually using it for the the many confusing reasons this creates.
• Anonymous
  December 15, 2003
  Very interresting. And yes, Kevin, you were great at conducting these internal C# courses ;-)
• Anonymous
  December 15, 2003
  <i>It's the same as saying:
  
  EndpointReference e = new EndpointReference(uri);
  SoapReceivers.Add(e, typeof(StockServiceRequestReceiver));
  </i>
  
  Well, yes, but that's the point -- it's taking one type an making it into another without you asking to do that. If you want the above code, then code it. The language/compiler/framework shouldn't allow that type changed to take place without your permission. That doesn't fit my definition of type safe.
  
• Anonymous
  September 23, 2005
  Hi
  
  I am trying to use SoapReceivers.Add and trying to use the EndpointReference as you said.
  
  But i get this error :
  The type or namespace name 'EndpointReference' could not be found (are you missing a using directive or an assembly reference?)
  
  I am just putting this:
  public static implicit operator EndpointReference(Uri uri)
  {
  return new EndpointRefernece(uri);
  }
  
  in the same class as i am using the SoapReceivers.Add
  
  Can someone please tell me more about how i get this to work?
  
  Thank you
  
  Mehul