메타-3장-방법

동적 디스크

class MyClass
    def my_method(my_arg)
        my_arg * 2
    end
end

obj = MyClass.new
obj.my_method(3)
# 6
obj.send(:my_method, 3)
# 6

동적method

class MyClass
    define_method :my_method do |my_arg|
        my_arg * 3
    end
end

obj = MyClass.new
obj.my_method(2)

팩시밀리

original code

class Computer
    def initialize(computer_id, data_source)
        @id = computer_id
        @data_source = data_source
    end

    def mouse
        info = @data_source.get_mouse_info(@id)
        price = @data_source.get_mouse_price(@id)
        info = "Mouse: #{info} (#{price})"
        return "* #{result}" if price >= 100
        result
    end

    def cpu
        info = @data_source.get_cpu_info(@id)
        price = @data_source.get_cpu_price(@id)
        info = "Mouse: #{info} (#{price})"
        return "* #{result}" if price >= 100
        result
    end

    def keyboard
        info = @data_source.get_keyboard_info(@id)
        price = @data_source.get_keyboard_price(@id)
        info = "Mouse: #{info} (#{price})"
        return "* #{result}" if price >= 100
        result
    end
end

동적 디스크 응용 프로그램

class Computer
    def initialize(computer_id, data_source)
        @id = computer_id
        @data_source = data_source
    end

    def mouse
        component :mouse
    end

    def cpu
        component :cpu
    end

    def keyboard
        component :keyboard
    end 

    def component(name)
        info = @data_source.send "get_#{name}_info" , @id
        price = @data_source.send "get_#{name}_price", @id
        info = "#{name.capitalize}: #{info} (#{price})"
        return "* #{result}" if price >= 100
        result
    end
end

동적 method 사용

class Computer
    def initialize(computer_id, data_source)
        @id = computer_id
        @data_source = data_source
    end

    def self.define_component(name)
        define_method(name) do
            info = @data_source.send "get_#{name}_info" , @id
            price = @data_source.send "get_#{name}_price", @id
            info = "#{name.capitalize}: #{info} (#{price})"
            return "* #{result}" if price >= 100
            result
        end
    end

    define_component :mouse
    define_component :cpu
    define_component :keyboard
end

한결

class Computer
    def initialize(computer_id, data_source)
        @id = computer_id
        @data_source = data_source
        data_source.methods.grep(/^get_(.*)_info$/) { Computer.define_component $1 }
    end

    def self.define_computer(name)
        define_method(name) do
            info = @data_source.send "get_#{name}_info", @id
            price = @data_source.send "get_#{name}_price", @id
            result = "#{name.capitalize}: #{info} (#{price})"
            return "#{result}" if price >= 100
            result
        end
    end
end

유령 방법

동적 방법

동적 방법을 사용한 팩스

class Computer
  def initialize(computer_id, data_source)
    @id = computer_id
    @data_source = data_source
    data_source.methods.grep(/^get_(.*)_info$/) { Computer.define_component $1 }
  end

  def self.define_component(name)
    define_method(name) do
      info = @data_source.get_keyboard_info(@id)
      price = @data_source.get_keyboard_price(@id)
      result = "keyboard: #{info} ($#{price})"
      price >= 100 ? "* #{result}" : result
    end
  end
end

Computer 클래스를 method로 설정팩스로

class Computer
  def initialize(computer_id, data_source)
    @id = computer_id
    @data_source = data_source
  end

  def method_missing(name)
    super if !@data_source.respond_to?("get_#{name}_info")
    info = @data_source.send("get_#{name}_info", @id)
    price = @data_source.send("get_#{name}_price", @id)
    result = "#{name.capitalize}: #{info} ($#{price})"
    price >= 100 ? "* #{result}" : result
  end

  def respond_to_missing?(method, include_private = false)
    @data_source.respond_to?("get_#{method}_info") || super
  end
end