From: Brian Candler <b.candler@...>
Date: 2008-09-22T16:49:51+09:00
Subject: Re: Iterating through a string

Siep Korteling wrote:
> a = (1..9).map{|n| n*n}
> 
> #versus my old way
> 
> a = [] #annoying
> (1..9).each{|n| a<<n*n}

FYI, there's another pattern for "building the result" without the 
annoying assignment:

  a = (1..9).inject([]) { |acc,n| acc << n*n }

Or in a more functional style (without any array mutation)

  a = (1..9).inject([]) { |acc,n| acc + [n*n] }

However in this case, map is perfectly appropriate. inject is useful 
when you're building something that isn't an Array - for example a 
String or a Hash.
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