Can't speak for tilly, but it's defaintely something that effects pretty much any language, though Perl might be worse off than most. If you have a method in your subclass, you always run the risk that the parent class will define a method with the same name, but with very different functionality.
I don't remember how the method is searched for in Java, but I believe that if you call that method in the parent, then it calls the parent class's version. This isn't true in Perl without some tricks.
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send money to your kernel via the boot loader.. This and more wisdom available from Markov Hardburn.