From: Scott <bauer.mail@...>
Date: 2006-03-20T05:43:49+09:00
Subject: Re: simple ruby language question

In class B, you are attepmting to use an instance variable as if it
were a class variable.  To set @blah to a value when its instantiated,
you'll need to stick that line in the constructor:

class B
  include A
  extend A

  def initialize
    @blah = 'YES!'
  end
end

Also, you dont need to both include and extend A inside B.  Use extend
when you want to use the modules methods as class methods:

module X
  def classy
    puts "Yup, I'm classy"
  end
end

class Y
  extend X
end

Y.classy
=>  Yup, I'm classy

You can also extend an instance of an object:

s = "Holy shniekes"
s.extend(X)
s.classy
=>  Yup, I'm classy

Use include when you want to "mix-in" the modules methods with the
instance methods defined in the class:

module X
  def classy
    puts "Yup, I'm classy"
  end
end

class Y
  include X
end

Y.new.classy
=>  Yup, I'm classy

Hope that helps :)

- Scott