具有来自includer类的静态方法调用的Ruby模块

在你的具体情况下。

module B 
  def self.included(base)
    base.const_set("CONST", base.find)
  end
end 

class A
  def self.find
    "AAA"
  end
  include B 
end

puts A::CONST

尽管有效,但还是有点乱。你确定你不能用不同的方式来实现你的目标吗?

在Ruby中实现这一点的更惯用方法是:

module B 
  def self.included(klass)
    klass.class_eval <<-ruby_eval
      CONST = find
    ruby_eval

    # note that the block form of class_eval won't work
    # because you can't assign a constant inside a method
  end
end

class A
  def self.find
    "AAA"
  end
  include B 
end

puts A::CONST

您所做的(class<<base)实际上将您置于A的上下文中 metaclass ,而不是它本身。这个 find 方法在其自身上,而不是其元类上。要记住的是类本身就是对象,因此有自己的元类。

为了让它更清楚:

class Human
  def parent
    # this method is on the Human class and available
    # to all instances of Human.
  end

  class << self
    def build
      # this method is on the Human metaclass, and
      # available to its instance, Human itself.
    end

    # the "self" here is Human's metaclass, so build
    # cannot be called.
  end

  def self.build
    # exactly the same as the above
  end

  build # the "self" here is Human itself, so build can
        # be called
end

module B 
  def self.included(base)
    class << base
      CONST = self.find
    end
  end
end 

class A
  class << self
    def self.find
       "AAA"
    end
  end
  include B 
end

那么编译器错误已修复,请尝试。