alias_method_example.rb

class MyClass

  def say_hello
    puts 'Hello Nick!'
  end

end

# Reopen the class to override the say_hello method
MyClass.class_eval do
  # alias_method creates a *copy* of the method object, it is not really a pointer (or alias)
  alias_method :say_hello_original, :say_hello
  # here we override and then call original method
  def say_hello
    puts 'I am the evil Nick!'
    say_hello_original
  end
end

x = MyClass.new
x.say_hello
# I am the evil Nick!
# Hello Nick!         <- proof that the alias_method is making a copy