This is my take on the less-aggressively-phrased argument in OaooBalancesYagni or SimpleDesignTrumpsYagni
(Yagni = YouArentGonnaNeedIt).

-- AlexChaffee

From http://www.purpletech.com/xp/bootstrap.txt :

8/6/2002: The past three sessions, my pairs and I have been refactoring the
Library and Item classes to be more object-oriented.  This follows one
of my big revelations, which I'm sure every Extreme Programmer must
learn, and must constantly relearn:

Simple Design trumps YAGNI

meaning that writing clean, clear, object-oriented code is very
important, and that if you have a choice between (a) leaving your code
smelly and implementing a new feature, or (b) refactoring and letting
the feature wait a little while, you should refactor.

Unfortunately, if you let your refactoring duties slip, you will end up
needing to perform a lot of refactorings with fairly large scope.
See NoseJobRefactoring for one technique for accomplishing this.

The bigger lesson, of course, is

Don't Check Your Brain At The Door

and that we should have been doing these OO refactorings all along.
Maybe even as soon as we got the code to work using "String title", we
should have taken half a step back, applied the "Replace Value With
Object" refactoring, and been satisfied that we had made the code more
aesthetically pleasing and therefore better --

-- ''even though'' it wasn't to satisfy a user story.

In other words, refactoring is a ''technical'' decision, not a business decision,
and the customer has no right to tell us not to do it (even if he does
so implicitly, or if it's just our own puritanical super-egos saying
"Work!  Be more productive!  Don't refactor, write a new story!").

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My take on YouArentGonnaNeedIt has always been that it applies to
''additions'' to functionality (including under-the-hood ones).
Under this understanding, one would never even think to skip
refactoring (or other SimpleDesign activities).

I know Yagni is one of those hammers that makes everything look like a
nail, and once the scales fall from your eyes it's tempting to find
lots of things you don't really need to be doing now.  Still, I don't
think it's intended to apply to anything but ''added complexity''
(which is clear if you read a lot of the arguments for Yagni, with
their references to carrying costs and the like).

Perhaps it's time to rename it: YouArentGonnaNeedThatFeature,
or YouArentGonnaNeedThatInfrastructure,
or YouArentGonnaNeedThatComplexity, or
YouArentGonnaNeedThatComplication, or maybe
YouArentGonnaNeedThatYet....

--GeorgePaci

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CategoryRefactoring