in reply to Write "Dumber" Functions
Who was it that suggested the "Principle of Least Surprise" for component behaviour? I'd say this is a rather gross violation of that rule. Sure, it's great to tell the programmer that they may have called the function improperly, but to die on ill-formed input, especially in a function that's supposed to check for validity, is extreme. (By all means carp about strange input -- bonus points if you provide a flag for debugging output, so that end users don't have to wade through a huge cascade of "hey, programmer, I think you've messed up" messages from a smart-ass module.)
As an aside, I can't stand the name 'check_date' for that function. Okay, it checks the date, but what does it do after checking the date? Die with an error? Return true ("yes, it's valid")? Return false ("yes, it's bogus")? Set a flag somewhere? How about is_valid_date instead?