From: dblack@...
Date: 2007-02-17T00:32:17+09:00
Subject: Re: class design issues

Hi --

On Fri, 16 Feb 2007, sur max wrote:

> But i think there is a point to discuss here...
>
> as lf1.name is simply an instance method which is(should be) only capable of
> returning the instance variable "@name"
>
> so by defining :name as attr_reader should block everything which is trying
> to write the instance variable "@name"

attr_reader just writes a wrapper method for you.  If the default
wrapper method doesn't do what you want, you can write a different
one:

   def x
     @x.dup
   end

If you want to do that a lot, you could write a new attr_* method:

   class Module
     def attr_reader_dup(*attrs)
       attrs.each do |attr|
         define_method(attr) { instance_variable_get("@#{attr}").dup }
       end
     end
   end

   class C
     attr_reader_dup(:x)
     def initialize
       @x = "don't change me"
     end
   end

   c = C.new
   c.x << "trying to change"
   p c.x                       # don't change me


David

P.S. Please don't top-post.  Just quote what you're responding to and
add your response.

-- 
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