From: Gary Wright <gwtmp01@...>
Date: 2009-07-23T05:19:38+09:00
Subject: Re: Instantiating classes / sharing data between classes


On Jul 22, 2009, at 3:15 PM, Trevoke wrote:
>>
>> I don't recommend class variables because their actual scope
>> is very non-intuitive (class hierarchy scope, not class scope)
>> and they add to the semantic load of a design when plain
>> old instance variables (on the class object) will do just fine.
>>
>> Gary Wright
>
> Gary -- these values ARE the same for EVERY SINGLE INSTANCE of the
> class, and are not meant to be changed.
> In this particular instance, are class variables fulfilling their
> destiny?


Here is a nice discussion of the confusion that surrounds
'class variables' and 'class instance variables' in Ruby:

<http://www.oreillynet.com/ruby/blog/2007/01/nubygems_dont_use_class_variab_1.html 
 >

Most people expect Ruby's class variables to behave like
Java or C++'s class variables but that is an incorrect assumption.

In Ruby, "instance variables of a class" are most closely
analogous to 'class variables' in Java or C++ and should
generally be used instead of Ruby's 'class variables'.

Gary Wright