Quick demo of overloading unary, binary operators.

gistfile1.rb

############################
#
#  The world is your oyster.  Unless you overload it.
#  Then it can be anything your heart desires.
#
#  Very few operators can't be overloaded:  and, or, not, &&, ||
#
class Person

  attr_reader   :my_bag
  attr_accessor :name
  
  def initialize(name = 'John Doe')
    @name = name
  end

  # Binary
  def +(person)
    "#@name: Hello #{person.name}"
  end

  def -(person)
    "#@name: Goodbye #{person.name}"
  end

  # Unary
  def +@
    "#@name: Hello world."
  end

  def -@
    "#@name: Peace world."
  end

  #  NOTE: I can overload ! but NOT 'not'...hinky.
  def !
    "#@name: What the fudge?!"
  end

  # Other
  def []=(key, value)
    @my_bag = "#@name found a #{key}, it reads: '#{value}'"
  end
end

dude  = Person.new "Ted"
dude1 = Person.new "John"


puts dude + dude1
# => Ted: Hello John

puts +dude
# => Ted: Hello world.

puts dude1 - dude
# => John: Goodbye Ted

puts -dude1
# => John: Peace world.

puts !dude
# => Ted: What the fudge?!

dude[:note] = "Booty on tap."
puts dude.my_bag
# => Ted found a note, it reads: 'Booty on tap.'