From: Matthias Reitinger <reitinge+usenet@...>
Date: 2009-07-22T09:35:07+09:00
Subject: Re: Mean method

�lph� Bl�� wrote:
> I adjusted the code a bit to handle the size factor with @size in 
> initialize (code changed if you refresh pastie).

Unfortunately this produces wrong results when the array changes in
between.  Consider this:

  array = [1,2,3,4]
  mean = Mean.new(array)
  puts mean.arithmetic # => 2.5
  array << 5
  puts mean.arithmetic # => 3.75
  puts Mean.new(array).arithmetic # => 3.0

As the size is only determined once in Mean#initialize, subsequent changes
of the array (size) go unnoticed.  This behaviour should at least be
documented.

-Matthias