From: Ryan Davis <ryand-ruby@...>
Date: 2011-08-03T05:31:43+09:00
Subject: Re: Documentation Improvement Proposal


On Aug 2, 2011, at 13:10 , Josh Vaughn wrote:

> Example that I did just yesterday.
> 
> ary = Array.new(r, Array.new(10))
> vs
> ary = Array.new(10) { Array.new(10) }
> 
> Seemingly the same, but they are not. User documentation might say the best way to do multi-dimensional array. Note I am learning and tried the first as I found that Array.new(some initial size, some initial value) was the basic Array API.

It does say how to do it:

% ri Array
...
       # only one copy of the object is created
       a = Array.new(2, Hash.new)
       a[0]['cat'] = 'feline'
       a
       a[1]['cat'] = 'Felix'
       a

       # here multiple copies are created
       a = Array.new(2) { Hash.new }
       a[0]['cat'] = 'feline'
       a
...