From: "Brian Schröder" <ruby.brian@...>
Date: 2005-05-23T21:29:01+09:00
Subject: Re: a deepcopy for "array = [1,2,3]*5"?

On 23/05/05, Boris <bvschmid@gmail.com> wrote:
> Been looking this up in the myriad of deepcopy strands, but couldn't
> find it in 30 minutes, so I'm posting the question.
> 
> The question is simple. What way would you create an array that
> contains 5 copies of an array, without the copies interfering with each
> other?
> 
> array = [1,2,3]*5
> 
> generates:
> [[1,2,3],[1,2,3],[1,2,3],[1,2,3],[1,2,3]]
> 
> but unfortunately also makes 'array[1][1] = "a"' change it like this:
> 
> [[1,"a",3],[1,"a",3],[1,"a",3],[1,"a",3],[1,"a",3]]
> 
> ---------
> Anyway, found a solution during tinkering, although I don't know why.
> Thought I'd just still post it anyway.
> 
> ar = []
> 5.times{ar << [1,2,3]}
> 
> works, and 'array[1][1] = "a"' results in the thing I want
> 
> [[1,2,3],[1,"a",3],[1,2,3],[1,2,3],[1,2,3]]
> 
> 

For me [1,2,3]*5 behaves different.

irb(main):001:0> [1,2,3]*5
=> [1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3]


For what you want you could use:

irb(main):002:0> a = Array.new(5) { [1,2,3] }
=> [[1, 2, 3], [1, 2, 3], [1, 2, 3], [1, 2, 3], [1, 2, 3]]
irb(main):003:0> a[1][1] = 'a'
=> "a"
irb(main):004:0> a
=> [[1, 2, 3], [1, "a", 3], [1, 2, 3], [1, 2, 3], [1, 2, 3]]

$ ruby -v
ruby 1.8.2 (2005-04-11) [i386-linux]

Which version of ruby are you using?

best regards,

Brian Schr�der

-- 
http://ruby.brian-schroeder.de/

Stringed instrument chords: http://chordlist.brian-schroeder.de/