From: Bulat Ziganshin <bulatz@...>
Date: 2002-10-30T16:03:36+09:00
Subject: Re: method-call style (was Re: Snippet: Tiny Featureless Ruby Web Server)

Hello Paul,

Tuesday, October 29, 2002, 9:56:04 PM, you wrote:
PB> In Ruby, attributes are method calls.  However, they are a special type
PB> of method call.  Attributes are guaranteed to never modify the object.
PB> And if the object isn't modified, then the attribute should remain the
PB> same.  I think the distinction is supported by the semantics of
PB> attributes, if not by the language itself.

attributes is just methods, automatically defined by attr_reader/...
built-in methods. you can write such methods as attr_reader himself
and some advanced OO libraries actually do this. it's easy:

class Class
  def reader attr
    module_eval <<-END_OF_EVAL
      def #{attr}
        @#{attr}
      end
    END_OF_EVAL
  end
end

class A
  def initialize(x0)
    @x = x0
  end
  reader "x"
end

a1 = A.new(23)
p a1.x
a2 = A.new(34)
p a2.x


-- 
Best regards,
 Bulat                            mailto:bulatz@integ.ru