From: Justin Bailey <jgbailey@...>
Date: 2006-03-29T07:23:57+09:00
Subject: Opposite of ||= pattern?

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A cheap just-in-time initialization trick is the "||=3D" trick:

def add_name(n)
  @name ||=3D Array.new
  @name << n
end

Now, how would you do the opposite of this pattern? More specifically, what
kind of construct would evaluate to a true value once, and then nil from
then on? I came upon this in the context of for loops, where I want a
one-time "starting" value to be present the first time through the loop,
then nil. And I wanted to do it in a cool way  - i.e. not just assign the
value to nil at the end of the loop, though of course that is the easiest
way.

Any thoughts?

Justin

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