How does one - without inheritance - override a class method and call the original from within the new method?

Question

I found one source which successfully overrode Time.strftime like this:

class Time
  alias :old_strftime :strftime
  def strftime
    #do something
    old_strftime
  end
end

The trouble is, strftime is an instance method. I need to override Time.now - a class method - in such away that any caller gets my new method, while the new method still calls the original .now method. I've looked at alias_method and have met with no success.

Answer 1

This is kinda hard to get your head around sometimes, but you need to open the "eigenclass" which is the singleton associated with a specific class object. the syntax for this is class << self do...end.

class Time
  alias :old_strftime :strftime

  def strftime
    puts "got here"
    old_strftime
  end
end

class Time
  class << self
    alias :old_now :now
    def now
      puts "got here too"
      old_now
    end
  end
end

t = Time.now
puts t.strftime