From: Henry Maddocks <hmaddocks@...>
Date: 2012-06-10T08:44:27+09:00
Subject: Re: Class variables and self


On 10/06/2012, at 9:20 AM, Mike Glaz wrote:

> so is self.total_count equal to self.class.total_count?

It depends where they are called. You need to know what self is at the point where the call is made. Going back to your sample code...

class Car

# At the point self == Car so self.total_count is the same as Car.total_count. 
# Note that this a method declaration, you are defining a class method.
 def self.total_count
   @total_count || 0
 end

[snip]

 def initialize(make)
  [snip]

# At this point, inside a method declaration self == an instance of Car NOT Car.
# So self.class is Car therefore this statement is the same as Car.total_count.
     self.class.total_count += 1
  

So in answer to your question, Yes they are the same object. Understanding when self changes and to what is a pretty important concept in Ruby.


Henry