From: "Ara.T.Howard" <Ara.T.Howard@...>
Date: 2005-10-19T23:16:35+09:00
Subject: Re: Array.sort when it's items are String inheritors with redefined <=> works like if not redefined

On Wed, 19 Oct 2005, MiG wrote:

> Hello,
> I want to have a string which, if in array, will be sorted like numbers. I 
> wrote this:
>
> -----------------------------------------------------------------------------------------
>
> class String2 < String
>
>    def <=> str2
>        self.to_i <=> str2.to_i
>    end
>
> end
>
> a = [ String2.new('1'), String2.new('10'), String2.new('5') ]
>
> puts a.sort.join(',')

put the method in Array:

   harp:~ > cat a.rb
   class Array
     def sort_as!
       map!{|elem| yield elem}
       sort!
       self
     end
     def sort_as
       dup.sort!
     end
   end


   a = %w( 1 10 5 )

   p a.sort_as{|s| Integer s}
   p a.sort_as{|s| Float s}
   p a.sort_as{|s| s.reverse }

   a.sort_as!{|s| Integer s}
   p a


   harp:~ > ruby a.rb
   ["1", "10", "5"]
   ["1", "10", "5"]
   ["1", "10", "5"]
   [1, 5, 10]

this avoids calling to_i, to_f, or whatever multiple times on the same object,
which will occur if you use either a spacship (<=>) operator or sort_by
approach.


hth.


-a
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