Why no Finalizer example in Effective C# 2nd Edition?

I received this feedback on the Safari site about an earlier draft of the 2nd Edition of Effective C#:

Text says: “You’ll notice that neither MyResourceHog nor DerivedResourceHog contain a finalizer. The example code I wrote does not directly contain any unmanaged resources. Therefore, a finalizer is not needed. That means the example code never calls Dispose(false). That’s the correct pattern. I take this to mean all I need is (assuming I need a finalizer):

} “

Is that it? What should be done in dervied classes? Please elaborate on this just a bit more and also include the finalizer in the code, just comment it out, so we can see the full pattern for the base and dervied classes. Thanks!

I intentionally did not include an example where you included a finalizer. In the vast majority of cases, you won’t include a finalizer. If you types do not include unmanaged resources, you don’t ever need to add a finalizer. This is also explained in “Framework Design Guidelines”, pp319-322.  The important reason for not including a finalizer (when you don’t need one) is that the presence of a finalizer (even if you call GC.SuppressFinalization()) affects performance. If it’s not needed, its presence is a needless performance robber.

And, if you do need a finalizer, you always need to implement IDisposable. Then, your finalizer is always as simple is shown above.

I chose not to include the expanded sample because I didn’t want to create and show a sample that would lead to a bad practice.

Created: 3/22/2010 5:54:48 PM

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