From: Gavin Sinclair <gsinclair@...>
Date: 2003-12-10T21:27:31+09:00
Subject: Re: Request for comments (longish)

On Wednesday, December 10, 2003, 10:33:44 PM, David wrote:

> This is a place where you could, conceivably, use my favorite
> 1.8.0-and-greater "trick":

>   class Operation
>     @derivatives = Hash.new {|k,v| raise "No class Operation::#{v}" }
>     # ...
>     def Operation.[](name)
>       @derivatives[name]
>     end

Love that trick.  Here's how I initialized a hash recently.  (The
algorithm called for setting some initial values and then removing
things as necessary.)

  # players == %w{Sam Min ...}
  result = Hash.new { |h,k| h[k] = [:white, :black] }
  result.values_at(*players)

End result of that:

  result == {
    "Sam" => [:white, :black],
    "Min" => [:white, :black],
    ...
  }

Oooooh... delicious.

Gavin