To refine this idea somewhat more, consider that there are quite a few Date modules (Date::Manip and Date::SimpleCalc) come to mind. How about writing up "In this situation I would use that module. Here's why." If you would roll your own solution (big can of worms here), explain why too.

For example, I stay away from Date::Manip because it's huge and usually overkill for my purposes. One of the other modules is usually more appropriate, or even using some special chromatic library code I wrote days ago (if I were in the habit of doing such a thing) is a better solution for performance reasons.