From: "Aleksi Niemelä" <aleksi.niemela@...>
Date: 2000-07-04T15:23:15+02:00
Subject: [ruby-talk:03795] Re: Array.uniq! returning nil

> As matz said in [ruby-talk:3785] and Dave said in [ruby-talk:1229],
> I often want to check if modification is done.

These and your example was exactly what I was looking for! Thank you.

Now I've come up with another proposition. We could change the behaviour in
next versions. (And of course provide a simple, yet most cases fixing
upgrade script.)  We could define obj.method! to *always* return the
possibly altered object.

And, now the new trick, add Array.uniq!? which would work like current
Array.uniq!. The actual semantic hint the developer should get when he sees
obj.method!? is 'this method modifies the object and returns something
(possibly boolean) describing if any action was taken'. 

In Array.uniq!? case we could return nil when the array was unchanged and
the modified array if it changed. (Or we could return array consisting of
removed items (items which had a duplicate), which is subject for another
debate. Which I could kill now by saying if one needs the array of items
which had duplicate on the original array he could say:

  array.dup - array.uniq!

I might be carrying method?:=$-冠 -notation too far here, but as you see we
have still plenty of ugly characters left for use :). Besides, this didn't
use any more ugly characters, it just combined old ones.

	- Aleksi