From: Martin DeMello <martindemello@...>
Date: 2010-03-31T18:30:50+09:00
Subject: Re: Pop Quiz: aliasing versus wrapping

On Wed, Mar 31, 2010 at 10:01 AM, Phrogz <phrogz@mac.com> wrote:
> Below are two files that differ only in the 2nd line of code in each.
> Can you guess what difference they will reveal? I must admit I was
> surprised when I ran into this.

It's pretty clear if you think of it in terms of message handlers and
method objects

>  class Object
>    alias_method :to_js, :inspect
>  end

This binds the message handler Object#to_js to the method object
Object#inspect. This should be illustrative:

$ cat test.rb
class Object
   alias_method :to_js, :inspect
   alias_method :inspect, :hash
end

a = Object.new
puts a.inspect
p a
puts a.to_js

$ ruby test.rb
67266180
67266180
#<Object:0x804cd08>

> $ cat wrapped.rb
>  class Object
>    def to_js; inspect; end
>  end

This creates a new method object, which contains a thunk that sends
the message "inspect" to self when it is invoked, and binds the
Object#to_js message handler to that method object.

martin