有一个常见的习惯用法。它使用included对象模型钩子。每当一个模块被包含到一个模块/类中时，这个钩子就会被调用。

module MyExtensions
  def self.included(base)
    # base is our target class. Invoke `extend` on it and pass nested module with class methods.
    base.extend ClassMethods
  end

  def mod1
    "mod1"
  end

  module ClassMethods
    def mod2
      "mod2"
    end
  end
end

class Testing
  include MyExtensions
end

t = Testing.new
puts t.mod1
puts Testing::mod2
# >> mod1
# >> mod2

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我个人也喜欢将示例方法分组到一个嵌套模块中，但据我所知，这是不太被接受的做法。

module MyExtensions
  def self.included(base)
    base.extend ClassMethods
    base.include(InstanceMethods)

    # or this, if you have an old ruby and the line above doesn't work
    # base.send :include, InstanceMethods
  end

  module InstanceMethods
    def mod1
      "mod1"
    end
  end

  module ClassMethods
    def mod2
      "mod2"
    end
  end
end

型

module Foo
 def self.included(m)
   def m.show1
     p "hi"
   end
 end

 def show2
   p "hello"

 end
end

class Bar
 include Foo
end

Bar.new.show2 #=> "hello"
Bar.show1 #=> "hi"

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是的。就像你想象的那样简单，因为Ruby的天才：

module Methods
    def mod
        "mod"
    end
end

class Testing
    include Methods # will add mod as an instance method
    extend Methods # will add mod as a class method
end

t = Testing.new
puts t.mod
puts Testing::mod

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或者，你可以这样做：

module Methods
    def mod1
        "mod1"
    end

    def mod2
        "mod2"
    end
end

class Testing
    include Methods # will add both mod1 and mod2 as instance methods
    extend Methods # will add both mod1 and mod2 as class methods
end

t = Testing.new
puts t.mod1
puts Testing::mod2
# But then you'd also get
puts t.mod2
puts Testing::mod1

型