But, really, all this [link|http://martinfowler.com/articles/newMethodology.html|"agile methods"] blither is looking more and more convincing to me... Certainly you are agile enough to CHANGE the constants into variables, should the need ever arise? Especially since the change wouldn't be all that big in the first place; the mechanics of file opening and reading and so on would positively dwarf it anyway.
(*): Misguided and best forgotten -- nay, best chopped into microscopic slivers, then burned to cinders and the ashes incinerated AGAIN, then buried under a mile-thick shield of depleted uranium at the bottom of the Marianas trench, and THEN forgotten! -- but, alas, undead like some fucking mummy in a cheesy horror flick.