From: "David A. Black" <dblack@...>
Date: 2008-05-02T20:57:12+09:00
Subject: Re: Beginner Question on Ruby

Hi --

On Fri, 2 May 2008, Arun Kumar wrote:

> Hi all,
>
> I am beginning to learn ruby and cant seem to reason this behaviour. I
> expect since empty or nill is the array, arr*n shouldnt change it.
>
> Why is this behaviour so?
>
> Code:
>
> num_arr = Array.new
> puts "Num Alpha: #{num_arr} and size: #{num_arr.size}"
> puts "Num Alpha: #{num_arr << num_arr} and size: #{num_arr.size}"
> num_arr.insert(-1, num_arr << num_arr)
> puts "Num Alpha: #{num_arr} and size: #{num_arr.size}"
>
> Output:
>
> Num Alpha:  and size: 0
> Num Alpha: [...] and size: 1
> Num Alpha: [...][...][...][...][...][...][...][...][...] and size: 3

You're inserting an array into itself. Ruby represents that kind of
recursive inclusion with dots.

irb(main):005:0> a = []
=> []
irb(main):006:0> a << a
=> [[...]]


David

-- 
Rails training from David A. Black and Ruby Power and Light:
   INTRO TO RAILS         June 9-12            Berlin
   ADVANCING WITH RAILS   June 16-19           Berlin
   INTRO TO RAILS         June 24-27           London (Skills Matter)
See http://www.rubypal.com for details and updates!