Disposing by setting to null?

Question

I'm aware of technique to handle IDisposable in a traditional manner. Say, in OnStop() method of windows service I close message queue client:

        if (client != null)
        {
            client.Dispose();
        }

For the first time today I saw one guy doing that this way:

        using (client)
        {
            client = null;
        }

What is exactly happening inside his "using" or does he dispose correctly at all?

Answer 1

The using(){} statement grabs a copy of the reference var so this assignment with null is ineffective.