santosh79

class Discounter
  def discount(*skus)
    expensive_calc(skus)
  end

  private
  def expensive_calc(*skus)
    puts "in expensive calc for #{skus}"
    skus.inject{|m,n| m + n}
  end

santosh79

class Discounter
  def discount(*skus)
    @memory ||= {}
    @memory[skus] = expensive_calc(skus) unless @memory.has_key?(skus)
    @memory[skus]
  end

  private
  def expensive_calc(*skus)
    puts "in expensive calc for #{skus}"

santosh79

class Discounter
  def discount(*skus)
    expensive_calc(skus)
  end

  private
  def expensive_calc(*skus)
    puts "in expensive calc for #{skus}"
    skus.inject{|m,n| m + n}
  end

santosh79

class Discounter
  def discount(*skus)
    expensive_calc(skus)
  end

  private
  def expensive_calc(*skus)
    puts "in expensive calc for #{skus}"
    skus.inject{|m,n| m + n}
  end

santosh79

class Discounter
  def discount(*skus)
    expensive_calc(skus)
  end

  private
  def expensive_calc(*skus)
    puts "in expensive calc for #{skus}"
    skus.inject{|m,n| m + n}
  end

santosh79

class Discounter
  def discount(*skus)
    expensive_calc(skus)
  end

  private
  def expensive_calc(*skus)
    puts "in expensive calc for #{skus}"
    skus.inject{|m,n| m + n}
  end

santosh79

module Memoize

  def remember(method)
    orig_method_name = "_original_#{method.to_s}_"
    alias_method orig_method_name.to_sym, method

    define_method(method) do |*args|
      @memory ||= {}
      @memory[args] = send(orig_method_name,args) unless @memory.has_key?(args)
      @memory[args]

santosh79

module Memoize

  def remember(method)
    original_method = instance_method(method)

    define_method(method) do |*args|
      @memory ||= {}
      bound_method = original_method.bind(self)
      @memory[args] = bound_method.call(args) unless @memory.has_key?(args)
      @memory[args]

santosh79

module Memoize

  def remember(method, &block)
    define_method(method, block)
    original_method = instance_method(method)

    define_method(method) do |*args|
      @memory ||= {}
      bound_method = original_method.bind(self)
      @memory[args] = bound_method.call(args) unless @memory.has_key?(args)

santosh79

class ShippingOption
  def self.children
    @children ||= []
  end

  def self.inherited(child_class)
    children << child_class
  end

  def self.for(weight, international)