Will using work on null?

Question

Will the following code work if resource doesn't implement IDisposable?

  T resource = new T();
  using (resource as IDisposable)
  {
     ...
  }

Answer 1

Yes. A using statement checks whether it's being given null and avoids trying to call Dispose if so.

From section 8.13 of the C# 3 spec:

A using statement is translated into three parts: acquisition, usage, and disposal. Usage of the resource is implicitly enclosed in a try statement that includes a finally clause. This finally clause disposes of the resource. If a null resource is acquired, then no call to Dispose is made, and no exception is thrown.