acts_as_paranoid for Rails 2.1

paranoid.rb

module Acts
  module Paranoid
    def acts_as_paranoid
      named_scope :not_deleted, :conditions => ["(deleted_at < ? OR deleted_at is null)", Time.now]
      class << self
        alias_method :find_with_deleted, :find
      end
      alias_method :destroy!, :destroy
      extend ClassMethods
      include InstanceMethods
    end
  end
  module ClassMethods
    def find(*args)
      not_deleted.find_with_deleted(*args)
    end    
  end
  module InstanceMethods
    def destroy
      update_attribute(:deleted_at, Time.now)
    end    
  end
end
ActiveRecord::Base.extend(Acts::Paranoid)