I'm in the middle of reading The Pragmatic Programmer by Andrew Hunt and Dave Thomas (http://www.pragmaticprogrammer.com/ppbook/index.shtml) and it talks about the finally block of the exception handling of some languages like ActionScript has and how it's useful in helping apply a number of principles described in the book. As a result I finally understand how to use the finally block.
The book talks about 2 principles:- a. Finish what you started. b. Don't Repeat Yourself (DRY). The DRY principle is about not writing the same bit of code more than once because things always change and it's human nature to forget/overlook all occurrences of some repeated bit code that needs to change. Hence bugs are introduced and maintenance increases and time to enhance existing code increases. Finish what you started is about resource management. The routine that opens/allocates/creates some resource should also destroy/release/close that resource. That way you don't run out of resources because it's opened in one place and closed in another or more places. Running out of resources is a bug that could of been avoided by managing that resource in one place. So how does the finally block help? The finally block is guaranteed to always be executed regardless of any error being caught or not. It's also guaranteed to be executed if the catch block exits the routine. So how does it help? If you created, for example, a movieclip and an error occurs, the principle of "finished what you started" says you need to destroy the movieclip in the routine that created it. Without the finally block, you would violate the DRY principle by destroying the movieclip in the catch block as well as at the end of the routine. By putting in a finally block, you only do that code once. Chris -- Chris Velevitch Manager - Sydney Flash Platform Developers Group www.flashdev.org.au _______________________________________________ Flashcoders mailing list [email protected] http://chattyfig.figleaf.com/mailman/listinfo/flashcoders
