From: ptkwt@...1.aracnet.com (Phil Tomson)
Date: 2001-08-12T14:04:08+09:00
Subject: [ruby-talk:19574] Why not access control for instance and class variables?



Maybe this is a silly question, but with all the recent talk about how 
subclasses can modify class variables 
and how that is possibly dangerous... why can't the access control 
functions (public,protected,private) be applied to class variables and 
instance variables as well?  So that if you had:

class Vehicle
  private
    @@number_of_Vehicles = 0
  public
  def initialize
    @@number_of_Vehicles += 1
    puts "there are now: "+@@number_of_Vehicles.to_s
  end
end

class Car < Vehicle
  def initialize
    super
  end

  def print_number_of_Vehicles
    p @@number_of_Vehicles #this would work since its a read-only access
  end

  def modify_number_of_vehicles(newValue)
    @@number_of_Vehicles = newValue #this would generate an access 
                                    #exception
  end
  
end

The pickaxe book indicates that access control functions are applied to 
methods only. 

Phil