From: Meino Christian Cramer <mccramer@...>
Date: 2003-08-17T00:29:34+09:00
Subject: Newbie Q: Data encapsulation with Ruby

Hi,

 as a beginner in C++ I learned that one advantage of OOP over the
 procedural programming is data hiding and encapsulation.

 In C++ this is achieved via the public:, protected: and private:
 keywords.

 As I currently (try to) understand, Ruby does it somehow different.

 class A
   def initializer( k_a )
     @a = k_a
   end
 end

 will declare a class A with a "totally private" attribute "a", which
 only can be accessed vie get/set-combos.

 Now I found (for me astonishling) two keywords:

	 attr_reader:	  
 
 and

	 attr_writer:

 which (seems to) totally "inifiltrate" the principle of data hiding
 and encapsulation.

 PLEASE!

 Dont misundertstood my words as any kind of critism on Ruby !!!

 I only want to express my current (mis)understanding of that what I
 try to understand.

 What is the secret behind attr_reader and attr_writer and how do they
 support OOP?

 Kind regards,
  Meino