Ruby `dup` vs. `clone`. For http://www.arnab-deka.com/posts/2009/07/ruby-dup-vs-clone/

clone_and_dup.rb

the_clone = p.clone
the_dup = p.dup

dup_vs_clone.rb

irb(main):018:0> the_clone.name
=> "The Man"
irb(main):019:0> the_dup.name
=> "The Man"
irb(main):020:0> the_clone.say_hi
=> "'sup"
irb(main):021:0> the_dup.say_hi
NoMethodError: undefined method `say_hi' for 
(Person :0xb7e83340 @name="The Man")
        from (irb):21
        from :0
irb(main):022:0> 

person.rb

class Person
  attr_accessor :name
end

person_say_hi.rb

p = Person.new
p.name = "The Man"

# now add a singleton method on p:
def p.say_hi
  "'sup"
end

validate.rb

irb(main):014:0> puts p.inspect
#<person :0xb7e83340 @name="The Man">
=> nil
irb(main):015:0> puts p.say_hi
'sup
=> nil