From: Jeremiah Bullfrog <jbullfro@...>
Date: 2004-09-14T17:34:54+09:00
Subject: Re: Recursive Objects (Arrays) in Ruby

On Mon, 13 Sep 2004 20:54:21 -0700, Wandering Mango wrote:

> #Problem line:
> puts testFormula1.characterType[0]
....
> test = Formula.new
> test.string = "A&B"
> test.wff
> 
> Now, Ruby exits with the following complaint:
> 
> in `wff': undefined method `characterType' for #<Formula:0xbceb0>
> (NameError)

I think the problem is, Ruby is not like C++ where one object 
can always read / change the internals of another if they're
of the same class. It looks like Ruby's 'protected' might 
produce that C++ behavior but I haven't used it. Pickaxe pg 236 
makes it look like it only works with methods and constants, 
ie you can't expose the raw variable itself. The easiest way to 
make accessors is to make the variable an 'attr'; eg 

class Formula
  attr :characterType # add ', true' if you want it writable too

  def initialize
    @string = nil
    @leftSub = nil
    @rightSub = nil
    @characterType = Array.new
  end

  # and I'm guessing something like this to give it C++ behavior
  # (ie what you were trying to do): 
  protected characterType, characterType= 
  # 'char..Type=' , only if you've specified a writer function 
  # for char..Type

....
end