Effective Antipatterns

My team has an "Effective Java Book Club" where we go over the book "Effective Java (3rd edition)" a few items at a time every couple of weeks. This is from Item 34 of that book.Whatever you do, don't do this.I keep saying to everyone that when you're writing code you're writing code for the next person that happens to read your code. You are not writing it for the compiler. I couldn't give a rat's ass about what the compiler and runtime will deal with. I care about the person who will read your code.Enums, in Java and most other languages, are a way of grouping named values together into a convenient structure. Java (and other languages as well) started to extend this to allow more class-like behaviors. If you're going to add a bit of metadata to the DayOfWeek enum to say weekend or weekday, then I'm all for it. It's still just a description of the value.But when you start to give computations to enums, I think you've gone too far.Programming is about communication of ideas to the next person. Enums mean a certain thing. This breaks that idea. This is surprising. Surprise isn't a good thing in programming.It's akin to making a getter that has side effects. Is it a valid bit of code? Sure it is. The compiler will make it do what you say. But the next person who calls it will get a rude awakening. And that's something that ought to be avoided.