From: Christoph <chr_mail@...>
Date: 2003-11-06T09:03:04+09:00
Subject: Re: Managing metadata about attribute types

dblack wrote:
...

> Of course the thing one probably wants to do is to modify classes and
> *not* break things :-) which is what singleton classes allow 
> you to do.  (See?  Matz thought of it already :-)  #extend is 
> lovely, because it sandboxes things rather effectively and 
> lets you do nice modular design.  For example, I've got a 
> program where I need a CGI object with extra capabilities.  
> Originally I subclassed CGI, but that broke something (I 
> think CGI must be particular about the return value of 
> #class, or something -- I didn't dig deeply to find it).  So 
> now I've got a module with which I extend my CGI object, and 
> I actually like that better.  It's nice and clean, and keeps 
> things tailored closely to the immediate needs of the objects.
 
H'm you are closet type-ist after all:-)

---
o = Object.new

module M
  def first_mth
  end
  def second_mth
  end
end

o.extend(M)

p o.is_a?(M)  # true
---

/Christoph