From: Greg Millam <walker@...>
Date: 2002-12-06T22:08:01+09:00
Subject: Re: Class-instance variables access

> I try to understand the difference between 'class variables' and 'class
> instance variables', following a post by Guy Decoux a few days ago.
>

If you've ever worked with C or Java, a class variable is like a variable
declared 'static'

class A
  def intialize(y)
    @x = y
    @@x = y
  end
  def test
    puts "@x: #{@x}"
    puts "@@x: #{@@x}"
  end
end

foo = A.new("foo")
bar = A.new("bar")

foo.test
bar.test

- You get:
@x: foo
@@x: bar
@x: bar
@@x: bar

@x is an instance variable that each instance stores it's own version of
@@x is a class variable that is stored in the class definition

@x can be different from instance to instance, @@x is the same for all
instances.


--

Greg Millam
walker at deafcode.com