Given SafeHandles these days, it should be rare that you actually implement a finalizer - especially if dealing with Windows handles/resources. From: [email protected] [mailto:[email protected]] On Behalf Of Joseph Clark Sent: Monday, June 14, 2010 11:50 PM To: ozDotNet Subject: Re: Implement IDisposable?
Good point, Michael. I didn't consider the implications of messing with other objects in the finalizer. :) On Tue, Jun 15, 2010 at 4:28 PM, Michael Minutillo <[email protected]<mailto:[email protected]>> wrote: The "Disposable Pattern" gets discussed a lot but I'm pretty sure you only need it when you are holding onto unmanaged resources. From a Finalizer you aren't supposed to mess with other objects, I presume this includes objects that the framework uses to wrap unmanaged resources for you. i.e. If you keep a FileStream object then you should dispose of it in your Dispose method. If you get to your own finalizer you should not touch the FileStream, it has its own finalizer to ensure it gets closed properly. That means you don't even need a finalizer. You almost never need a finalizer. You pretty much never need to implement the full disposable pattern. At least, that's how I understand it. If you are holding onto com objects directly then it might be a different story but for Files and SqlConnections and so on it shouldn't be required. On Tue, Jun 15, 2010 at 2:02 PM, Joseph Clark <[email protected]<mailto:[email protected]>> wrote: I'm no expert, but I understand there is a "proper" way to implement IDisposable to ensure that things always get cleaned up properly. Implementing IDisposable allows you to cleanly release your resources as soon as practical, but relies on the consumer to call the Dispose method properly. So, to get around this, you can also define a Finalizer for your class that performs your cleanup, in the event that IDisposable is not called. The problem is that Finalizers have a bunch of caveats attached to them (related to performance and memory consumption) and thus shouldn't be defined unless you really, really need them. So, the trick is to call GC.SuppressFinalize in your Dispose method, which stops the Finalizer from running needlessly (I don't know about C#, but if you implement IDisposable in VB.NET<http://VB.NET>, the IDE automatically injects a correct implementation of this pattern for you). I did a quick Google search and found a codeproject article which looks accurate enough and covers it in more detail: http://www.codeproject.com/KB/cs/idisposable.aspx Hope this helps. My knowledge of finalizers is only theory-based. Joe. On Tue, Jun 15, 2010 at 3:34 PM, Bec Carter <[email protected]<mailto:[email protected]>> wrote: Hi! I have a class which uses temporary files to do its stuff. What do you recommend for ensuring things get cleaned up when things go bad? IDisposable? Or perhaps a big try/finally inside the class functions? Cheers --Bec-- -- Michael M. Minutillo Indiscriminate Information Sponge Blog: http://wolfbyte-net.blogspot.com
