From: Keith Rarick <kr@...>
Date: 2007-08-30T08:40:49+09:00
Subject: Re: python-style decorators

On 8/29/07, Daniel DeLorme <dan-ml@dan42.com> wrote:
> what about:
>    class C
>      decorate :memoized do
>        def ...
>      end
>    end
>
> That makes the implementation much more simple and solid than relying on
> method_added which may be incorrectly overridden somewhere.

I like that. I think the gain in robustness more than offsets the
slight degradation (IMO) in readability. What would it look like for
class methods? Something like this? I don't know how I would implement
example 2 below.

class C

  # Example 1 (instance method)
  decorate :memoized do
    def tak(x, y, z)
      return z if x <= y
      tak(tak(x - 1, y, z), tak(y - 1, z, x), tak(z - 1, x, y))
    end
  end

  # Example 2 (class method)
  decorate :memoized do
    def self.tbk(x, y, z)
      return z if x <= y
      tbk(tbk(x - 1, y, z), tbk(y - 1, z, x), tbk(z - 1, x, y))
    end
  end

  # Example 3 (class method)
  class << self
    decorate :memoized do
      def tck(x, y, z)
        return z if x <= y
        tck(tck(x - 1, y, z), tck(y - 1, z, x), tck(z - 1, x, y))
      end
    end
  end

end

kr