From: Claus Spitzer <DocBoobenstein@...>
Date: 2004-05-11T18:36:23+09:00
Subject: Re: [Q] Array.new - strange behavior

On Tue, 11 May 2004 18:18:59 +0900, E.-R. Bruecklmeier
<unet01@radio-eriwan.de> wrote:
> 
> dear rubyists,
> 
> today i noticed a strange bahavior in Array.new while defining multi
> dimentional arrays:
> 
> p "P1"
> foo = Array.new(3,[0,0])
> foo.each do |foo1|
>    p foo1.id
> end

I think I had a similar problem when I started with Ruby (coming from
the C/C++ environment)... the solution was what you had following...

> 
> p "P2"
> foo = Array.new
> 3.times {foo.push [0,0]}
> foo.each do |foo1|
>    p foo1.id
> end
> 
> produces:
> 
> "P1"
> 19645868
> 19645868
> 19645868
> "P2"
> 19645760
> 19645748
> 19645736
> Completed(0)
> 

Interestingly, I get different results: 

irb(main):001:0> p "P1"
"P1"
=> nil
irb(main):002:0> foo = Array.new()
=> []
irb(main):003:0> 3.times{
irb(main):004:1* foo << Array.new( 0, 0 )
irb(main):005:1> }
=> 3
irb(main):006:0> foo.each{ |i|
irb(main):007:1* p i.id
irb(main):008:1> }
20999324
20999312
20999300
=> [[], [], []]
irb(main):009:0> foo = Array.new()
=> []
irb(main):010:0> 3.times{
irb(main):011:1* foo.push [0,0]
irb(main):012:1> }
=> 3
irb(main):013:0> foo.each{ |i| p i.id }
20964584
20964572
20964536
=> [[0, 0], [0, 0], [0, 0]]
irb(main):014:0>

> Is it intentional that the new method fills the array with just one
> instance of [0,0]? In my sense this is a violation of the PoLS.
> 
> Thanks for any hints.
> 
> Eric.
> 
>