You should use what you think is best. Probably the most common methods are: returning a special value (undefined, 0, empty string, empty list, -1, MAX_INT) or performing a die. I fancy the latter, but I use the former often as well. The former has two drawbacks: you can't return a value that indicates "error" if there's no error, and you either have to reserve an range of special values, or you can't signal what went wrong, other than scribbling the reason away somewhere (compare open returning false, and using $! to indicate the reason).

Throwing an exception (die) doesn't suffer from this. You don't "lose" possible return values, and you can do the "return" and reason all at once, just die with a reason. The caller still needs to do two things, using eval and checking $@, but the caller already needed to do two things.

But please use whatever you are most comfortable with. And that might vary from project to project. Or even from method to method.

Abigail