From: "Berger, Daniel" <Daniel.Berger@...>
Date: 2006-04-14T03:03:43+09:00
Subject: Re: Question mark in attr_*



> -----Original Message-----
> From: Patrick Hurley [mailto:phurley@gmail.com] 
> Sent: Thursday, April 13, 2006 11:23 AM
> To: ruby-talk ML
> Subject: Re: Question mark in attr_*
> 
> 
> On 4/13/06, Wiebe Cazemier <halfgaar@gmx.net> wrote:
> > Hi,
> >
> > Methods which return booleans end with a question mark, by 
> convention. 
> > But how about boolean attributes (attr_[reader, accessor, writer])? 
> > Saying "attr_reader :variable?" won't work. I find it 
> rather strange 
> > when you have to access boolean attributes without the 
> question mark, 
> > but the methods with the question mark.
> >
> >
> >
> 
> As ruby does not have data types, the onus is on the 
> developer to spell out that she/he wants such an accessor. So 
> add this to your
> program:
> 
> class Module
>  def battr_reader(sym, *more)
>    battr_reader(*more) unless more.empty?
>    define_method("#{sym}?") { 
> !!instance_variable_get("@#{sym}") }  end end
> 
> Then you can add a battr_reader to any class...
> pth

FYI, I brought this issue up at
http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/5796, where
attr_ methods did what you meant with regards to '?' and '!'.

Regards,

Dan