From: RichardOnRails <RichardDummyMailbox58407@...>
Date: 2011-04-21T22:50:35+09:00
Subject: Re: Using the spaceship operator

On Apr 21, 12:13 am, RichardOnRails
<RichardDummyMailbox58...@USComputerGurus.com> wrote:
> Hi,
>
> Here an abstract version of my app, in which I have an array of two-
> element arrays I'd like to sort on the second element of each pair
> using the spaceship operator:
>
> $data = [ [:A, 12], [:B, 30], [:C, 4] ]
>
> Class MyTest < Array
>     def <=>(other)
>         self[1] <=> other[1]
>     end
>
>     @sorted_array = $date
>  end
>
> How can I make this work?
>
> Thanks in advance,
> Richard

Hi John and Brian,

Thank you very much for your extremely insightful answers.

I've been oscillating between:
	Metaprogramming Ruby
	The Well-Oriented Rubyist
	Design Patterns in Ruby

But I didn't see anything in them for my sorting problem, so I Googled
for it.  Thus I  found this concise method, but I couldn't figure out
how to make "self" be my array of arrays.

John: Thanks for that sort_by method using a block to return the
specific value (from each element) I want the sort method to use.
Very tidy!

Brian: Thanks for
1. addressing my key issue about how to make "self" be my array, so to
speak.  Question,  would that redefinition of <=> contaminate uses of
"sort" in other top-level classes?  I could test for an answer, but I
might miss something.
2. using "delegation", which I've seen in those textbooks but not yet
internalized.

Best wishes,
Richard