A minor nitpick: > And some of the other lessons, like "don't use method_missing if you can define a method instead", are well worth considering as well. I'd

A minor nitpick: > And some of the other lessons, like "don't use method_missing if you can define a method instead", are well worth considering as well. I'd argue that this one also falls into the category of "simpler/more readable and, incidentally, more performant". When defining methods you get the correct behaviour of respond_to? for free, whereas when overriding method_missing, you also have to take care of defining a corresponding respond_to?. The main reason for choosing def/define_method over method_missing (when possible) should be that it is generally simpler to do so.