How does one tell if an IDisposable object reference is disposed?

Question

Is there a method, or some other light-weight way, to check if a reference is to a disposed object?

P.S. - This is just a curiousity (sleep well, not in production code). Yes, I know I can catch the ObjectDisposedException upon trying to access a member of the object.

Answer 1

No - default implementation of IDisposable pattern does not support it

Answer 2

System.Windows.Forms.Control has an IsDisposed property which is set to true after Dispose() is called. In your own IDisposable objects, you can easily create a similar property.

Answer 3

It depends, there are IDisposable objects that allow to call the Dispose method as much as you want, and there are IDisposable objects that throw ObjectDisposedException. In such a case these objects must track the state (usually implemented with a private boolean field isDisposed).

Answer 4

If it is not your class and it doesn't provide an IsDisposed property (or something similar - the name is just a convention), then you have no way of knowing.

But if it is your class and you are following the canonical IDisposable implementation, then just expose the _disposed or _isDisposed field as a property and check that.

Answer 5

There is nothing built in that will allow this. You would need to expose an IsDisposed boolean property that reflects an internal disposed flag.

public class SimpleCleanup : IDisposable
{
    private bool disposed = false;

    public bool IsDisposed
    {
       get
       {
          return disposed;
       }
    }

    public SimpleCleanup()
    {
        this.handle = /*...*/;
    }

    protected virtual void Dispose(bool disposing)
    {
        if (!disposed)
        {
            if (disposing)
            {
               // free only managed resources here
            }

            // free unmanaged resources here
            disposed = true;
        }
    }

    public void Dispose()
    {
        Dispose(true);
    }
}