如何从ruby中的内部类访问外部类的类变量 [英] how to access a class variable of outer class from inner class in ruby

问题描述

我在下面有一些 Ruby 代码:

i have some code in Ruby here below:

class A
  @@lock = Monitor.new
  class B
    def method
      @@lock.synchronize
        puts "xxxxx"
      end
    end
  end
end    

运行后抛出一个错误，内容如下:

after running it throws an error which said that below:

A::B 中未初始化的类变量@@lock (NameError)

如果我想知道如何从内部类B的方法访问外部类A的类变量@@lock，该怎么做?提前致谢.

if i want to know how to access the outer class A's class variable @@lock from inner class B's method, how to do it? thank you in advance.

推荐答案

访问这个类变量的唯一方法是通过访问器方法

The only way to access this class variable is via an accessor method

class A
   def self.lock
     @@lock ||= Monitor.new
   end

   class B
     def method
       A.lock.synchronize
         puts "xxxxx"
       end
     end
   end
 end

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