"class" methods in Ruby

gistfile1.rb

class Book
  # This is a "class" method
  def Book.catch_em_all
    "I'm sorry, you can't do that Dave"
  end

  # This is also a "class" method, since "self" right now is the
  # Class object instance for this "class"
  def self.bind_it(spell)
    "We're still working on binding books with spell."
  end

  class << self
    # This is another "class" method, now we have changed into the
    # eigen-"class" of this "Book" Class object instance.
    def my_mind_hurts
      "Stop gulping frozen water!"
    end

    def delegate_to_secret
      only_the_book_knows
    end

  private

    # This is a private "class" method!!
    def only_the_book_knows
      "Yep only me!"
    end
  end
end

# One last one for your. Add directly to the eigen-"class"
def Book.oh_my
  "（╯°□°）╯︵( .o.)"
end

p Book.catch_em_all
# => "I'm sorry, you can't do that Dave"
p Book.bind_it("(ﾉ◕ヮ◕)ﾉ*:･ﾟ✧")
# => "We're still working on binding books with spell."
p Book.my_mind_hurts
# => "Stop gulping frozen water!"
#p Book.only_the_book_knows
# => NoMethodError: private method `only_the_book_knows' called for Book:Class
p Book.delegate_to_secret
# => "Yep only me!"
p Book.oh_my
# => "（╯°□°）╯︵( .o.)"