From: me@...
Date: 2007-04-10T23:25:06+09:00
Subject: What happens to instance variables in modules when they are extended into classes

Hi,

Please take a look at the code pasted at this URL (I will include the
code in the body of this message (below) for future readers, but the
rafb.net post will give readers for the next 24 hours something better
to look at): http://rafb.net/p/9MkY3H79.html

Why is it that an instance method of the module gets mixed into the
class, but instance variables of the module do not get mixed in?

Whats the best strategy for writing instance methods in a module that
depend on some state in the mixee?

Thanks very much,
Mike.

And now here is the code snippet:

module M
  @module_instance_variable = 'miv'

  def module_instance_method
    @module_instance_variable
  end
end


class C
  extend M
end


puts "Is module_instance_method in the methods of the class?
#{C.methods.include?('module_instance_method')}"
puts "Is @module_instance_variable in the instance variables of the
class? #{C.instance_variables.include?('@module_instance_variable')}"
puts "Is @module_instance_variable in the class variables of the
class? #{C.class_variables.include?('@module_instance_variable')}"