array_trick.rb

# A sample class...
class Person
  attr_accessor :name, :gender, :born_on

  def initialize(name, age, born_on)
    self.name    = name
    self.gender  = gender
    self.born_on = born_on
  end

  def <=>(other)
    # Even though this is a protected method, members of the same class can 
    # access each other's protected methods. I bet you thought you'd never 
    # need to know that!
    sortable_attributes <=> other.sortable_attributes
  end

  protected

  def sortable_attributes
    [name, gender, born_on]
  end
end

# Some data...

p1 = Person.new("Jimmy", :male,   "1982-5-16")
p2 = Person.new("Sonya", :female, "1986-2-4")
p3 = Person.new("Beth",  :female, "1990-10-4")
p4 = Person.new("Beth",  :female, "1970-2-14")

# Now sort!

[p1, p2, p3, p4].sort #=> [p4, p3, p1, p2]