From: Robert Klemme <shortcutter@...>
Date: 2011-11-29T01:09:40+09:00
Subject: Re: Is high-speed sorting impossible with Ruby?

2011/11/28 Matthias Wächter <matthias@waechter.wiz.at>:
> On 28.11.2011 15:17, Gaurav C. wrote:
>>
>> What's the difference between Array.new(1e6+1) {|n| ""} and
>> Array.new(1e6+1, "")?
>
> The first one creates one array with 1e6+1 _different_ empty strings. The
> second one results in an array that holds 1e6+1 references to the _same_
> empty string.

Another way to visualize this:

irb(main):001:0> Array.new(4, "").map(&:object_id)
=> [135176100, 135176100, 135176100, 135176100]
irb(main):002:0> Array.new(4, "").map(&:object_id).uniq
=> [135107180]
irb(main):003:0> Array.new(4){""}.map(&:object_id)
=> [134679150, 134679140, 134679110, 134679080]
irb(main):004:0> Array.new(4){""}.map(&:object_id).uniq
=> [134358730, 134358720, 134358710, 134358670]

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/