From: matz@... (Yukihiro Matsumoto)
Date: 2004-03-08T12:58:45+09:00
Subject: Re: proposal:  class<<obj to invoke extend_object

Hi,

In message "Re: proposal:  class<<obj to invoke extend_object"
    on 04/03/08, Simon Strandgaard <neoneye@adslhome.dk> writes:

|> Describe yourself deeper.  What exactly is your proposal? 
|
|When 'class<<obj' is seen by Ruby, then an init method should be invoked.
|I propose to reuse #extend_object and #extended for this.
|
|> And why do you think it's needed?
|
|Its difficult to add an new instance variable to obj.
|Its inflexible compared to obj.extend(Mod), because there isn't
|invoked an #extend_object method when the extension occurs.

You didn't explain why you need "extended" for singleton class
definition.  Why don't you use extend for your purpose, before
changing the language?

|> Remember, since singleton class always exists for each object
|> (virtually), 'class <<obj' is rather corresponds to class re-opening.
|
|I am only little familiar with class re-opening..

I want you to take a break and learn about Ruby before claiming apples
and oranges are similar.  Yes, they are.  But not the same.  Besides
that, singleton class definition is a kind of class re-opening, so
that they should remain same.

Class re-opening is a class definition whose target is an existing
class, for example:

  class String
    def foo     # String#foo become available
    end
  end

there's no hook for class re-opening.

							matz.