From: Navindra Umanee <navindra@...>
Date: 2005-01-30T14:59:23+09:00
Subject: Re: Ten Things Every Java Programmer Should Know About Ruby

Joao Pedrosa <joaopedrosa@gmail.com> wrote:
> > An object in Ruby may even change its type from one moment to the
> > other.  A Socket object may suddenly become a File object.
> 
> dewd@heaven:~ $ irb
> irb(main):001:0> a = b = "ccc"
> => "ccc"
> irb(main):002:0> a = 1
> => 1
> irb(main):003:0> a == b
> => false
> irb(main):004:0> b
> => "ccc"

Why give an uninteresting fake example, when I already gave a concrete
real example where an object changes its type from Socket to File?

irb(main):001:0> require 'socket'
=> true
irb(main):002:0> file = File.new("/dev/full")
=> #<File:/dev/full>
irb(main):003:0> socket = TCPSocket.new("www.ruby-lang.org", 80)
=> #<TCPSocket:0x402c86e8>
irb(main):005:0> mutant_object_pointer = socket
=> #<TCPSocket:0x402c86e8>

irb(main):006:0> mutant_object_pointer
=> #<TCPSocket:0x402c86e8>
irb(main):007:0> mutant_object_pointer.class
=> TCPSocket

irb(main):008:0> socket.reopen(file)
=> #<File:/dev/full>

irb(main):009:0> mutant_object_pointer
=> #<File:/dev/full>
irb(main):010:0> mutant_object_pointer.class
=> File

Cheers,
Navin.