Deletable attachment module for Paperclip

has_deletable_attachment.rb

module TheWebFellas
  module HasDeletableAttachment

    def self.included(base)
      base.extend(ClassMethods)
    end

    module ClassMethods
      def has_deletable_attachment(*attr_names)
        attr_names.each do |name|
          attr_accessible "delete_#{name}"
          before_validation "delete_#{name}_before_validation"

          define_method("delete_#{name}=") do |value|
            instance_variable_set("@delete_#{name}", value.respond_to?(:to_i) ? !value.to_i.zero? : value)
          end

          define_method("delete_#{name}") do
            !!instance_variable_get("@delete_#{name}")
          end
          alias_method "delete_#{name}?", "delete_#{name}"

          define_method("delete_#{name}_before_validation") do
            attachment = send(name)
            attachment.clear if send("delete_#{name}?") && !attachment.dirty?
            true
          end
          protected("delete_#{name}_before_validation")
        end
      end
    end

  end
end

modules.rb

ActiveRecord::Base.send(:include, TheWebFellas::HasDeletableAttachment)