Joe Duffy's Blog

So you may or may not have noticed that System.IO.Stream both has a Close() method and implements IDisposable, meaning it has a Dispose() method, too. (Note: it’s explicitly implemented, meaning that to access it you’ll need to use an IDisposable typed reference in C#, e.g. as in ((IDisposable)myStream).Dispose()). Stream is an abstract base class, the most common derivitive being FileStream.

Without consulting Reflector, ;) can you answer these questions?

• What does invoking Close() on an open Stream do?
• What does invoking Dispose() on an open Stream do?
• Should you call both at some point in a Stream’s lifecycle?
  • If so, when and in what order?
  • If not, why?
• Can you call only one without having to call the other?
• Is it weird that there is both a Close() and Dispose() on a single type, or does that seem natural? Based on your understanding of the pattern, do you think we should continue to use it, or is there a better one?

I have a much lengthier post that I’m writing up regarding an internal design debate we’re currently involved in - responses will help to shape both the post and the debate. :)