From: Joel VanderWerf <vjoel@...>
Date: 2006-10-30T03:09:12+09:00
Subject: Re: keeping a hash' sort order?

ara.t.howard@noaa.gov wrote:
...
> if you really want to sort on arbitrary keys use an rbtree:
> 
>     harp:~ > cat a.rb
>     require 'rbtree' # rubyforge or raa
> 
>     rb = RBTree.new
> 
>     class Key < ::String
>       attr 'arbitrary'
>       def initialize value, arbitrary
>         super value
>         @arbitrary = arbitrary
>       end
>       def <=> other
>         self.arbitrary <=> other.arbitrary
>       end
>     end
>     def Key(*a, &b) Key.new(*a, &b) end
> 
>     rb[ Key("a", 3) ] = 1
>     rb[ Key("b", 2) ] = 2
>     rb[ Key("c", 1) ] = 3
> 
>     rb.each{|k,v| p [k,v]}
> 
> 
> 
>     harp:~ > ruby a.rb
>     ["a", 1]
>     ["b", 2]
>     ["c", 3]

What's the 'arbitrary' part for? The Key#<=> method is not called. The 
following has the same output:

     rb = RBTree.new

     rb[ "a" ] = 1
     rb[ "b" ] = 2
     rb[ "c" ] = 3

     rb.each{|k,v| p [k,v]}



-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407