how to access a class variable of outer class from inner class in ruby

Question

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

after running it throws an error which said that below:

uninitialized class variable @@lock in A::B (NameError)

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.

DigitalRoss · Accepted Answer · 2011-01-14 06:46:13Z

6

I don't think you can without defining an accessor.

Class B is lexically scoped inside of A, so its real name is A::B and various other things are different.

But it's not a child or any other sort of derived class, so it doesn't actually have any special rights to see private or protected or otherwise local elements of A.

answered Jan 14, 2011 at 6:46

DigitalRoss

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Comments

Jacob Relkin · Accepted Answer · 2011-01-14 06:42:31Z

1

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

answered Jan 14, 2011 at 6:42

Jacob Relkin

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