From: Gary Wright <gwtmp01@...>
Date: 2011-05-29T11:06:29+09:00
Subject: Re: Method that mutates object


On May 28, 2011, at 8:51 PM, Chad Perrin wrote:
> . . . and I haven't even tried adding an instance variable to that module
> yet.  How should I add an instance variable to my fixnum object if not
> with extend?

We are talking about two different things.  You are talking about modifying the singleton class, which you can't do.  It is prohibited because it would kill performance to dispatch through singleton classes for some of the core data types.

But you can manually add instance variables:

3.instance_variable_set("@english", "three")


Or you can modify the Fixnum class:

class Fixnum
	attr_accessor :english
end

4.english = "four"

In either case you've got fixnum objects with state that can change.

Gary Wright