From: Andrew Walrond <andrew@...>
Date: 2005-05-05T22:28:20+09:00
Subject: Re: Fwd: Re: Whats so different about a Hash?

On Thursday 05 May 2005 13:57, ts wrote:
> >>>>> "A" == Andrew Walrond <andrew@walrond.org> writes:
>
> A> $ ruby --version
> A> ruby 1.8.2 (2004-11-27) [i686-linux]
>
>  Can you update to the latest stable
>

See other message - same result as you.

But is this the _correct_ behaviour?

The reason this came up was because I wanted to use hashes as keys in hashes. 
Consider:

 irb(main):001:0> a={} => {}
 irb(main):002:0> a[{1=>2}]=3 => 3
 irb(main):003:0> a[{1=>2}]=3 => 3
 irb(main):004:0> a[{1=>2}]=3 => 3
 irb(main):005:0> a.inspect => "{{1=>2}=>3, {1=>2}=>3, {1=>2}=>3}"

but

 irb(main):018:0> a={} => {}
 irb(main):019:0> a[[1,2]]=3 => 3
 irb(main):020:0> a[[1,2]]=3 => 3
 irb(main):021:0> a[[1,2]]=3 => 3
 irb(main):022:0> a.inspect => "{[1, 2]=>3}"

Not at all what I was expecting! Is there a good reason why

 irb(main):029:0> [1,2]==[1,2] => true
 irb(main):030:0> [1,2]===[1,2] => true
 irb(main):031:0> [1,2].eql?([1,2]) => true

but

 irb(main):033:0> {1=>2}=={1=>2} => true
 irb(main):034:0> {1=>2}==={1=>2} => true
 irb(main):035:0> {1=>2}.eql?({1=>2}) => false

?

Andrew