attr_* methods invoked from private methods behave differently in REE 1.8.7 and MRI 1.9.2

attrs_18_vs_19.rb

require 'rubygems'
require 'active_support'

module Attrs
  extend ActiveSupport::Concern

  module ClassMethods
    def add_public_accessor(name)
      add_accessor(name)
    end

    private
    def add_accessor(name)
      # in REE 1.8.7, attrs defined directly private methods still have public visibility
      # in MRI 1.9.2, attrs defined directly in private methods have private visibility
      attr_accessor name.to_sym
    end
  end
end

module EvalAttrs
  extend ActiveSupport::Concern

  module ClassMethods
    def add_public_accessor(name)
      add_accessor(name)
    end

    private
    def add_accessor(name)
      # in REE 1.8.7 and MRI 1.9.2, attrs defined usingher=' called forprivate method `bar=' called for visibility of the enclosing method
      class_eval { attr_accessor name.to_sym }
    end
  end
end

# works in 1.8 but not 1.9
class ClassWithAttrs18
  include Attrs
end

# works in 1.8 and 1.9
class ClassWithEvalAttrs
  include EvalAttrs
end

ClassWithEvalAttrs.add_public_accessor('foo')
ev_attrs = ClassWithEvalAttrs.new
ev_attrs.foo = 'hello'  # works in REE 1.8.7 and MRI 1.9.2
puts "foo = #{ev_attrs.foo}"

ClassWithAttrs18.add_public_accessor('bar')
attrs = ClassWithAttrs18.new
attrs.bar = 123  # fails with a private method `bar=' called for object (NoMethodError) in MRI 1.9.2
puts "bar = #{attrs.bar}"