From: Ralph Shnelvar <ralphs@...32.com>
Date: 2009-11-28T08:00:32+09:00
Subject: Re: Class variables, instance variables, singleton; Ruby v. C++

DM> On Friday 27 November 2009 01:07:45 pm Ralph Shnelvar wrote:
>> Newb here coming from C++
>> 
>> Ok, I _think_ I know what a class variable is.  It is similar to a
>> static variable in a class in C++.  Rght?

DM> Yes.

DM> A quick warning, though: Class variables behave weirdly with inheritance.
DM> Avoid them. Since all Ruby classes are themselves objects, it makes more sense
DM> to define an instance variable of the class.

DM> That is, instead of doing this:

DM> class Foo
DM>   def bar
DM>     @@some_count += 1
DM>   end
DM> end

DM> Do this:

DM> class Foo
DM>   def self.increment_count
DM>     @some_count += 1
DM>   end
DM>   def bar
DM>     self.class.increment_count
DM>   end
DM> end

DM> If you understand how that works, you should be able to understand this
DM> example, which is how I'd actually do it:

I am clueless what all of the above does.  It is WAY over my head.

I have read that section on how self is set in the Pickaxe book a
dozen times ... and I'm still lost.

How would I go about deciphering the meaning of what you wrote, above?

DM> class Foo
DM>   class << self
DM>     attr_accessor :some_count
DM>   end
DM>   def bar
DM>     self.class.some_count += 1
DM>   end
DM> end


And this is even more obscure to me.