From: Joel VanderWerf <joelvanderwerf@...>
Date: 2010-06-06T09:48:31+09:00
Subject: Re: 1.9 warning for 'private' and possible bug

Luis Lavena wrote:
> On Jun 5, 6:25 pm, Joel VanderWerf <joelvanderw...@gmail.com> wrote:
>> Consider this error:
>>
>> $ cat t.rb
>> module M
>>    private
>>    def attr_accessor(*args); super; end
>> end
>>
>> class C
>>    extend M
>>    attr_accessor :x
>> end
>>
>> C.new.x = 1
>>
>> $ ruby19 t.rb
>> t.rb:11:in `<main>': private method `x=' called for
>> #<C:0x0000000091c670> (NoMethodError)
>>
>> That looks very suspect, so I was about to file a bug report. But then I
>> noticed that there is a warning reported with the -v switch:
>>
>> $ ruby19 -v t.rb
>> ruby 1.9.2dev (2010-05-31) [x86_64-linux]
>> t.rb:3: warning: private attribute?
>> t.rb:11:in `<main>': private method `x=' called for
>> #<C:0x000000012e5670> (NoMethodError)
>>
>> Does anyone understand this warning? Is 'private' (without an argument)
>> deprecated?
> 
> Maybe is because you're setting private for all the following methods,
> including the ones that attr_accessor defines moving forward after the
> "extending"?
> 
> if you change the private to 'private :attr_accessor'  there is no
> warning and things works.

True. However:

$ cat t.rb
module M
   private
   def attr_accessor(*args); super; end
   public # <-- added this line
end

class C
   extend M
   attr_accessor :x
end

C.new.x = 1

$ ruby t.rb
$ ruby19 t.rb
t.rb:12:in `<main>': private method `x=' called for 
#<C:0x00000001e40858> (NoMethodError)