gistfile1.rb

$ irb
>> module M; protected; attr_reader :foo end
=> nil
>> class C; include M end
=> C
>> C.public_instance_methods.include?('foo')
=> false

$ jirb
>> module M; protected; attr_reader :foo end
=> nil
>> class C; include M end                   
=> C
>> C.public_instance_methods.include?('foo')
=> true

$ jirb
>> module N; def self.included(base) base.class_eval { attr_reader :bar; protected :bar } end end                      
=> nil
>> class C; include N end
=> C
>> C.public_instance_methods.include?('bar')
=> false