From: Lars Christensen <larsch@...>
Date: 2008-07-02T19:32:02+09:00
Subject: Ruby Idiom for dynamic programming? (request for comments)

Random idea i had...

I sometimes make custom classes/method for caching output of
functions, i.e. for dynamic programming. To generalise this, i though
it would be possible to implement it like this:

class A
  def func(a, b, *c)
    puts "Computing... #{[a,b,c].inspect}"
    return [a,b,c].hash
  end
  cached :func
end

My 'cached' directive is defined as:

class Module
  def cached(method, cache = (@@funccache ||= {}))
    orig = "uncached_#{method}"
    alias_method orig, method
    define_method method do |*args|
      key = [ method, args ]
      @@funccache[key] ||= send(orig, *args)
    end
  end
end

What's the scope of @@funccache? (What 'object' holds it?). Is there a
better way to do it?

Lars