From: Florian Gross <flgr@...>
Date: 2005-01-20T04:16:02+09:00
Subject: Re: value by reference

Mark Hubbart wrote:

> when you call Ref.new(obj), you get back a Ref object, which will
> appear in every way to be the "obj" that you passed to Ref.new. It
> will give the same id, behave the same, respond to the same methods,
> etc.
> 
> Only two differences (that I see):
> First, it responds to two extra methods: __value__ and become. become
> replaces the object that is being referenced, and returns the old
> value. __value__ returns the object being referenced, without the Ref
> wrapper. You should use this method any time you want to serialize or
> Marshal the value.
> Second, it circumvents the public/private method checks, so you can
> call private methods directly on the reference. Sorry. Don't have the
> time to figure out how to fix that without eval.

Third:

Ref.new(false) or Ref.new(nil) do not act like you would expect them to 
in conditional contexts:

do_something if ref # always done
x = ref || y # x is always ref

Fourth:

Some of Ruby's C methods want their arguments to be instances of a 
particular class. They won't even call the usual #to_x methods. 
str.scan(ref) is one example of that.

Fifth:

Object.instance_method(:inspect).bind(ref).call calls the #inspect 
method of the ref, not of the Object it refers to.