Ruby Memoization(转载)_Ruby_编程开发_程序员俱乐部

module Memoizable
    def memoize( name, cache = Hash.new )
        original = "__unmemoized_#{name}__"
        ([Class, Module].include?(self.class) ? self : self.class).class_eval do
            alias_method original, name
            private
            original
            define_method(name) { |*args| cache.has_key?(args) ? cache[args] : cache[args] ||= send(original, *args) }
        end
    end
end

include Memoizable

def fib(n)
    return n if (0..1).include? n
    fib(n-1) + fib(n-2)
end

memoize :fib