System.IO.Stream disposable with a reader

Question

Can't remember where I read it, but I remember a MS guy saying that once you create a reader around a System.IO.Stream, then the stream is not longer responsible for the disposal of the stream.

Is this true? Can someone confirm this? Maybe provide a reference.

This means the outer using in this code is redundant

using (var s = new FileStream(@"c:\file.txt",FileMode.Open)) {
    using (var reader = new StreamReader(s)) {
         reader.ReadToEnd();
    }
}

Answer 1

read the approved answer to this question:

http://stackoverflow.com/questions/674879/who-disposes-of-an-idisposable-public-property/675001#675001

It says that StreamReader always disposes the underlying stream.

Answer 2

Both FileStream and StreamReader implement IDisposable, so I would use both using's regardless, that way if the underlying implementation were to change, however unlikely, your code would still be good.

Answer 3

If isn't redundant, for the reason that the "new StreamReader(s)" line could fail (throw an exception). That would mean that no using block is going to Dispose() the stream. In reality, this is unlikely... but it could! For example, the stream might be non-readable (or whatever).

Thus, it is always best to guard such initialization; far better to be disposed twice than not at all. Plus it makes it obvious to the reader (and any code analysis tools) that you have definitely cleaned up after yourself.