From: dblack@...
Date: 2006-03-24T04:25:03+09:00
Subject: Re: questions/suggestions from a Ruby newbie

Hi --

On Thu, 23 Mar 2006, Pit Capitain wrote:

> dblack@wobblini.net schrieb:
>> This reminds me of my favorite way to create an pseudo-auto-vivifying
>> hash:
>>
>>   Hash.new {|h,k| h[k] = h.dup }
>> 
>> :-)  I don't think there's an equally concise way for the array thing.
>
> David, is this really working for you?
>
>  x = Hash.new {|h,k| h[k] = h.dup }
>  x[1] = "x1"
>  x[2]
>  p x    # => {1=>"x1", 2=>{1=>"x1"}}
>
> Maybe you mean
>
>  Hash.new {|h,k| h[k] = h.dup.clear }

Oh, I knew someone would find a problem with it :-)  I think that's
right (the 'clear').  I'd only tested it, if it's worthy of the name
test, with things like: x[1][2][3].

Even so, I think it's still the most concise implementation of this
concept.


David

-- 
David A. Black (dblack@wobblini.net)
Ruby Power and Light, LLC (http://www.rubypowerandlight.com)

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