From: Nigel Wilkinson <nigel@...>
Date: 2005-06-18T08:51:05+09:00
Subject: Why do arrays work this way?

Hi folks

I'm using ruby 1.8.2 as comes with Mandriva 2005LE and get the following 
behaviour with arrays which doesn't seem logical to me.

In irb I do

irb(main):058:0* a=[1,2,3,4,5]
=> [1, 2, 3, 4, 5]

straight forward enough

irb(main):059:0> b=a
=> [1, 2, 3, 4, 5]
irb(main):060:0> c=a
=> [1, 2, 3, 4, 5]

I've set 2 more variables to equal 'a'

irb(main):061:0> b[3] = 'w'
=> "w"

I believe this changes index 3 in'b' to now be equal to 'w'

do
irb(main):062:0> b
=> [1, 2, 3, "w", 5]

that's exactly as I expected, BUT

irb(main):063:0> a
=> [1, 2, 3, "w", 5]
irb(main):064:0> c
=> [1, 2, 3, "w", 5]

so what's the logic behind 'a' & 'c' changing when I change 'b'.

Is this a bug? and if not what's the reasoning behind this behaviour please.



Best Rgds from confused of Heathfield
Nigel
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