方法中的Ruby模块包含

Question

在课堂上,Foo我想Bar在某些条件下包括方法:

 module Bar
   def some_method
     "orly"
   end
 end

 class Foo
   def initialize(some_condition)
     if !some_condition
       "bar"
     else
       class << self; include Bar; end
     end
   end
 end

是否有更清晰(更清晰)的方法来实现include方法而不必在单例类中进行？

Answer 1

extend是include单身类的等价物:

module Bar
  def some_method
    puts "orly"
  end
end

class Foo
  def initialize(some_condition)
    extend(Bar) if some_condition
  end
end

Foo.new(true).some_method # => "orly"
Foo.new(false).some_method # raises NoMethodError