From: James Coglan <jcoglan@...>
Date: 2009-04-14T05:46:00+09:00
Subject: Re: changing array values

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> For some reason, when I run the code below:
>
> class TEST
>  def initialize(args)
>    @args = args
>  end
>  def describe
>    return @args.join(", ")
>  end
> end
>
>
> def test
>  old = [0,0,0,0,0,0]
>  tests = []
>  5.times do |i|
>    new = old
>    new[rand(old.size)] = rand(5) # randomly changes one of the members
> of the array to a number from 0 to 4
>    tests[i] = TEST.new(new)
>    puts tests[i].describe
>  end
>  return tests
> end
>
> I get this output:
>
> 0, 0, 0, 0, 0, 0
> 0, 0, 0, 0, 0, 1
> 0, 0, 0, 0, 0, 4
> 0, 0, 0, 2, 0, 4
> 0, 0, 1, 2, 0, 4
> [#<TEST:0x3f3d9f0 @args=[0, 0, 1, 2, 0, 4]>,
> #<TEST:0x3f3d9d8 @args=[0, 0, 1, 2, 0, 4]>,
> #<TEST:0x3f3d900 @args=[0, 0, 1, 2, 0, 4]>,
> #<TEST:0x3f3d828 @args=[0, 0, 1, 2, 0, 4]>,
> #<TEST:0x3f3d750 @args=[0, 0, 1, 2, 0, 4]>]



When you set 'new = old', you're just creating another reference to the same
array. To copy the array, use 'new = old.dup'. (dup = duplicate)

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