ruby - 我可以从同一个模块添加类方法和实例方法吗？

Question

新手问题:

我知道 include 和 extend 是如何工作的，我想知道是否有办法从单个模块中同时获取类和实例方法？

这就是我使用两个模块的方式:

module InstanceMethods
    def mod1
        "mod1"
    end
end

module ClassMethods
    def mod2
        "mod2"
    end
end

class Testing
    include InstanceMethods
    extend ClassMethods 
end

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

感谢您抽出宝贵时间...

Answer 1

有一个常见的成语。它使用included 对象模型钩子(Hook)。每次将模块包含到模块/类中时都会调用此 Hook

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

我个人也喜欢将实例方法分组到一个嵌套模块中。但据我所知，这种做法不太被接受。

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