Why disposed object doesn't throw exception on using it after disposing?

Question

Is it legal to call a method on disposed object? If yes, why?

In the following demo program, I\'ve a disposable class A (which implements IDisposa

Answer 1

Disposed doesn't mean gone. Disposed only means that any unmanaged resource (like a file, connection of any kind, ...) has been released. While this usually means that the object doesn't provide any useful functionality, there might still be methods that don't depend on that unmanaged resource and still work as usual.

The Disposing mechanism exist as .net (and inheritly, C#.net) is a garbage-collected environment, meaning you aren't responsable for memory management. However, the garbage collector can't decide if an unmanaged resource has been finished using, thus you need to do this yourself.

If you want methods to throw an exception after the object has been diposed, you'll need a boolean to capture the dispose status, and once the object is disposed, you throw the exception:

public class A : IDisposable
{
   int i = 100;
   bool disposed = false;
   public void Dispose()
   {
      disposed = true;
      Console.WriteLine("Dispose() called");
   }
   public void f()
   {
      if(disposed)
        throw new ObjectDisposedException();

      Console.WriteLine("{0}", i); i  *= 2;
   }
}