Ruby bits (module 篇)


Outline
  1. 1. 目錄 (module 篇)
  2. 2. 1. NAMESPACE（避免同樣的 method name）
  3. 3. 2. MIXIN
    1. 3.1. include: 可直接當作 instance method 來 include
    2. 3.2. MIXINS（像是多重繼承） VS CLASS INHERITANCE（只能單一superclass）
    3. 3.3. extend: 可直接當作 class method 來 extend

目錄 (module 篇)

modules as being very much like classes, only modules can’t create instances and can’t have subclasses. They’re just used to store things!

  1. NAMESPACE
  2. MIXIN

1. NAMESPACE（避免同樣的 method name）

image_utils.rb

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module ImageUtils
  def self.preview(image)
  end
  def self.transfer(image, destination) 
  end
end

run.rb

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require 'image_utils'
image = user.image
ImageUtils.preview(image)
  • example 2
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module Math
  PI = 3.141592653589793
end
puts Math::PI #=> 3.141592653589793

2. MIXIN

include: 可直接當作 instance method 來 include

IMAGE_UTILS.RB

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module ImageUtils
  def preview
  end
  def transfer(destination) 
  end
end

AVATAR.RB

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require 'image_utils'
class Image
  include ImageUtils
end

RUN.RB

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image = user.image
image.preview

MIXINS（像是多重繼承） VS CLASS INHERITANCE（只能單一superclass）

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class Post
  include Shareable
  include Favoritable
end
class Image
  include Shareable
  include Favoritable
end
class Tweet
  include Shareable
  include Favoritable
end
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module Shareable
  def share_on_facebook
  end
end

module Favoritable
  def add_to_delicious
  end
end

extend: 可直接當作 class method 來 extend

HOOKS

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module ImageUtils
  def preview
  end
  def transfer(destination)
  end
  module ClassMethods
    def fetch_from_twitter(user)
    end 
  end
end
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class Image
  include ImageUtils
  extend ImageUtils::ClassMethods
end
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image = user.image
image.preview                      # instance method
Image.fetch_from_twitter('gregg')  # class method



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