From: "David A. Black" <dblack@...>
Date: 2009-02-13T03:04:09+09:00
Subject: Hash order (was: Re: If you are unhappy with the direction of Ruby 1.8.7+, respond)

Hi --

On Fri, 13 Feb 2009, James Coglan wrote:

>>
>>
>>
>> What do you mean with "Hash ordering"?
>> An order for Hash instances? Hash doesn't define a <=> method.
>> Or iteration order of Hash elements? That wasn't defined
>> in 1.8.6 (I don't know if it is in 1.8.7).
>
>
>
> In 1.8.6, iteration order would be the same as the order that the keys
> appear in the source. To work with 1.8.7, you need to create an empty hash
> and add keys one by one rather than putting them all in a hash literal (see
> the patch).

Hashes aren't ordered at all in 1.8, as far as I know. This works the
same in 1.8.6 and 1.8.7:

irb(main):002:0> h = {3,4,1,2}
=> {1=>2, 3=>4}
irb(main):003:0> h.each {|*x| p x }
[[1, 2]]
[[3, 4]]
=> {1=>2, 3=>4}

and here's a 1.8.7 case with individual key insertion:

irb(main):001:0> h = {}
=> {}
irb(main):002:0> h[3] = 4
=> 4
irb(main):003:0> h[1] = 2
=> 2
irb(main):004:0> h.each {|*x| p x }
[[1, 2]]
[[3, 4]]


David

-- 
David A. Black / Ruby Power and Light, LLC
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