Designing an interface always requires careful considerations of how it will be used. Scott Meyers elegantly catches the entire problem in one sentence in his book Effective C++:

Make interfaces easy to use correctly and hard to use incorrectly.

The people at Microsoft who were in charge for the WCF client code generation either hadn’t read that book or didn’t understand it. They have made an interface that is counter intuitive and hard to use when it comes to disposing of the WCF client.

In my previous post IDisposable and using in C# I wrote that “Always call Dispose on objects implementing IDisposable“. This is true, as long as the class implements IDisposable in a reasonable way. Unfortunately the WCF client doesn’t. The MSDN docs presents the problem.

using (CalculatorClient client = new CalculatorClient())
{
    ...
} // <-- this line might throw
Console.WriteLine(
  "Hope this code wasn't important, because it might not happen.");

That is definitely an example of an interface that is hard to use. The hidden call to Dispose might throw with a strange exception which sometimes even hides the real error. There is a simple solution though that makes the above code work as expected.
Continue reading →