Smart::comments is a perl module that implements "intelligent" comments that can aid in debugging and tracking program execution flow. they can report the value of a variable, track the progress of a loop, and verify that particular assertions are true.

best of all, when you're finished debugging, you don't have to remove them. simply commenting out the "use smart::comments" line turns them back into regular comments. leaving smart comments in your code is smart because if you needed them once, you'll almost certainly need them again later.