array of streams in c sharp

Question

Typically I declare streams inside of a using statement to ensure that the stream is properly disposed when I am done with it, and so that I don't mistakenly call it when I'm outside the using block.

Some examples here: MSDN using Statement Reference

How does one use a using statement with an array of streams? Would it be equivalent to declare the array outside of a try/catch/finally block and call each stream's dispose method in the finally block?

Lastly, how does one test that the streams have been properly disposed?

Answer 1

You have to do what using does without using using.

This means looping through the array and calling Dispose on each instance ( after casting explicitly to IDisposable, if needed). Do that loop in the finally block.

Lastly, you don't test for them being properly disposed. Once you call Dispose, you should just null them out, since you can't use them anymore.

Answer 2

I would create a new object that holds the Streams in it. Something like this (not totally fleshed out):

class StreamHolder : IDisposable
{
  List<Stream> Streams {get;}

  public void  Dispose()
  {
      Streams.ForEach(x=>x.Dispose()):
  }
}

This way you can put the container object in the using statment, it will will handle the stream disposal for you. Your other option is the handle it in the Finally block, but if I were going to do this in more than one place, I would like to encapsulate it, so I don't accidentally forget to dispose of all the streams when I am done.

Answer 3

The using () statement is a pattern for disposal intended to re-inforce good habits, but it is not required. There are plenty of situations where you need to store objects outside the lifetime of a scoped function.

While I think you should probably architect in a way where you can use the using() statement, the essential thing is that in some encopassing finally block, you dispose each of the streams.

To answer the last question, it does not appear that the Stream class has any method or property to determine if it has been closed/disposed, however if the IDisposable pattern is implemented correctly, you can call Close/Dispose again if you need to be sure.