Question

I have the following code:

class MyClass  
  module MyModule
    class << self

      attr_accessor :first_name

      def myfunction
        MyModule.first_name = "Nathan"
      end

    end
  end
end

When I call the method myfunction like so, it works fine:

> me = MyClass::MyModule.myfunction
=> "Nathan"
> me
=> "Nathan"

But if I removed the class << self and add a self. prefix to myfunction, it doesn’t work.

For example:

class MyClass  
  module MyModule

    attr_accessor :first_name

    def self.myfunction
      MyModule.first_name = "Nathan"
    end

  end
end


> me = MyClass::MyModule.myfunction
NoMethodError: undefined method `first_name=' for MyClass::MyModule:Module

I’m trying to understand the class << self method. I thought it was a way add the self. prefix to the all the methods inside of it, but if that was true, why doesn’t it work if I remove it and prefix each method with self. manually?

Thanks in advance for your help.

Answer 1

This is because your attr_accessor :first_name is also wrapped by the class << self.

To do it the way you suggest, you can use mattr_accessor like so:

require 'active_support'

class MyClass  
  module MyModule

    mattr_accessor :first_name

    def self.myfunction
      MyModule.first_name = "Nathan"
    end

  end
end