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> 1) Delete most of the comments 2) Stuff breaks. WTF? The code was processing its own comments!

My campfire story: change method name, stuff breaks. Method names had been parsed in a wrapper object (Python's __getattr__ being abused) so that calling 'setFoo()' triggered a 'Foo_changed' event. In fact, the method names constituted a mini-language with its own grammar and semantic. Apparently someone had gotten high on reflection.

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Corollary: AOP is the enemy of refactoring.

You unwittingly changed one of the (seemingly unused/unnecessary) pointcuts and your aspects aren't firing anymore. While not impossible to track down, these problems are difficult to resolve.

I am not sure if this was AOP though maybe I'm committing the no true Scottsman fallacy here. Side note: decorators were not present in Python then, so there was no easy way to do the cutpoint thing in a visible way.

This worries me every time I use AOP, but I mitigate that risk by writing integration tests which assert that the aspects are doing what they are intended to, and also to raise an alarm if somebody unknowningly breaks them.

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