From: "Jan E." <lists@...>
Date: 2012-06-10T08:18:19+09:00
Subject: Re: Class variables and self

Mike Glaz wrote in post #1063878:
> so is self.total_count equal to self.class.total_count?

No, of course not. self refers to the particular instance of Car, 
whereas self.class refers to the *class* of this instance, i. e. Car 
itself. Those are two completely different objects.

Since the instances of Car don't even have a total_count method, calling 
self.total_count will throw an exception (try it yourself).

It's important to distinguish between the methods of the class and the 
methods of the instances. The Car class has three new methods: 
total_count, total_count= and add_make. The instances of Car also have 
three new methods: make_mates, initialize and make (the latter is 
created by attr_reader).

Check it for yourself:

puts Car.methods(false)
my_ferrari = Car.new('Ferrari')
puts my_ferrari.methods(false)

The "false" argument suppresses the inherited methods.

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