From: David Brady <ruby_talk@...>
Date: 2005-11-10T02:41:30+09:00
Subject: Writing my own attr_* methods

Hi All,

I frequently find myself creating member vars that contain a status flag 
that want me to write a ? method.  I know ruby can be tricked into 
thinking it has an additional attr_ method, but off the top of my head I 
can't think where I'd inject that method and how.

I figure some guru will know what to do to Kernel, Class or Object to 
make this work:

----------8<----------8<----------8<----------
class Foo
  attr_flag  :bar, :baz
  attr_flag_ro  :qaz, :qux, :quux
   
  def initialize(qaz, qux, quux)
    @qaz=qaz; @qux=qux; @quux=quux
    @bar = @baz = false
  end
end

f = Foo.new(true, true, true)

f.bar = true
f.baz = true

puts "Yay!" if f.bar?
puts "Yay!" if f.baz?
puts "Yay!" if f.qaz?
puts "Yay!" if f.qux?
puts "Yay!" if f.quux?
----------8<----------8<----------8<----------

I don't know if attr_flag, attr_flag_ro is the right pairing--perhaps 
attr_flag would be read only and if you want it to be settable you want 
to call attr_accessor, etc.

Anyway, I'm not sure this is a perfect design, mostly I'm interested in 
seeing *how* to write an attr_ method.

Thoughts?

Thanks!

-dB

-- 
David Brady
ruby_talk@shinybit.com
C++ Guru. Ruby nuby.  Apply salt as needed.