From: nobu.nokada@...
Date: 2001-12-23T12:44:16+09:00
Subject: [ruby-talk:29344] Re: a better way?

At Sun, 23 Dec 2001 10:43:41 +0900,
David Alan Black <dblack@candle.superlink.net> wrote:
> I think the design is that some calculation will only be performed
> once, then cached -- one of these guys:

Another one using Hash#fetch,

  class Temp
    @@save = {}
    def fahrenheit(c)
      @@save.fetch(c) do
        puts "Performing calculation...."
        @@save[c] = c * 9 / 5 + 32
      end
    end
  end

Or in recent 1.7.2,

  class Temp
    @@save = Hash.new do |h, c|
      puts "Performing calculation...."
      h[c] = c * 9 / 5 + 32
    end
    def fahrenheit(c)
      @@save[c]
    end
  end


Nobu Nakada