From: SonOfLilit <sonoflilit@...>
Date: 2007-05-30T22:35:23+09:00
Subject: Enumerable#serially - those nifty functions w/o memory footprint

Hello,

I've seen many people write things like:

(1..1000000).to_a. # anything that is a huge enumerable can work as an example
  collect{|x| num_appearances(x)}.select{|x|
x.is_norwegian?}.collect{|x| x.paycheck}.each{|x| p x}

I almost wrote something like that myself today.

The problem, of course, is the huge memory footprint - collect,
select, collect each creates a new temporary array to store the
results in.

Here's a solution to that problem, exchanging it for a bit of speed
(anything that uses those methods could obviously live with that,
otherwise another language or method would be used):

module Enumerable
  def serially(&b)
    self.collect{|x| *([x].instance_eval(&b)}
  end
end

Just beware not to use it with sort or any of the "!" methods or with
sort or sort_by.

Aur