From: "Brian Schröder" <ruby.brian@...>
Date: 2005-05-05T20:24:19+09:00
Subject: Re: Whats so different about a Hash?

On 05/05/05, Andrew Walrond <andrew@walrond.org> wrote:
> Consider:
> 
>  irb(main):001:0> a=1 => 1
>  irb(main):002:0> b=1 => 1
>  irb(main):003:0> c={} => {}
>  irb(main):004:0> c[a]=1 => 1
>  irb(main):005:0> c[b]=1 => 1
>  irb(main):006:0> c.inspect => "{1=>1}"
> 
> and
> 
>  irb(main):007:0> a="K" => "K"
>  irb(main):008:0> b="K" => "K"
>  irb(main):009:0> c={} => {}
>  irb(main):010:0> c[a]=1 => 1
>  irb(main):011:0> c[b]=1 => 1
>  irb(main):012:0> c.inspect => "{\"K\"=>1}"
> 
> and
> 
>  irb(main):013:0> a=[1,2] => [1, 2]
>  irb(main):014:0> b=[1,2] => [1, 2]
>  irb(main):015:0> c={}=> {}
>  irb(main):016:0> c[a]=1 => 1
>  irb(main):017:0> c[b]=1 => 1
>  irb(main):018:0> c.inspect => "{[1, 2]=>1}"
> 
> But the hash behaves differently:
> 
>  irb(main):019:0> a={1=>2} => {1=>2}
>  irb(main):020:0> b={1=>2} => {1=>2}
>  irb(main):021:0> c={} => {}
>  irb(main):022:0> c[a]=1 => 1
>  irb(main):023:0> c[b]=1 => 1
>  irb(main):024:0> c.inspect => "{{1=>2}=>1, {1=>2}=>1}"
> 
> Why?
> 
> I'm going for another coffee ;)
> 
> Andrew Walrond
> 
> 

I think the difference is:

irb(main):005:0> [1,2].hash === [1,2].hash
=> true
irb(main):006:0> {1=>2}.hash === {1=>2}.hash
=> false

regards,

Brian

-- 
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