First of all let me say GREAT BOOK. Thanks to all involved.

Here's a question: in C# you use "using" in VB you specifically call dispose. The first time this comes up is in Chapter 5. That's great, I understand what dispose does, but what I'm not clear about is the objects that are chosen to dispose. In the Chapter 5 code dispose is called in the functions that use datasets. Why isn't dispose called to get rid of parameters or datareaders for example? How do you determine which objects are disposed by you and which are disposed by the framework?

Thanks

Dispose is a method you call to dispose of 'valuable' resources (files, sockets, etc.). Dispose is also used with managed objects that have references to unmanaged objects. With these types of scenarios, the user of the class needs to be able to explictly 'free' these resources (since you don't want to wait for the garbage collector to free them - who knows when that will happen). So, Dispose is the standard way to do this.

Someone who is creating this type of class is supposed to implement the IDisposable interface. This interface has one method called Dispose(). So, if you see a class that inherits from IDisposable, you know you should call Dispose() on it as soon as you're done with it. Note that calling Dispose does not destroy/garbage collect the object. Although, it will probably put the object in an unstable/unusable state. You will usually get an ObjectDisposedException thrown if you try to use the object after calling Dispose().

Hope this helps.

Tim Rogers