ActiveRecord::Suppressor prevents the receiver from being saved during a given block.

For example, here's a pattern of creating notifications when new comments are posted. (The notification may in turn trigger an email, a push notification, or just appear in the UI somewhere):

class Comment < ActiveRecord::Base
  belongs_to :commentable, polymorphic: true
  after_create -> { Notification.create! comment: self,
    recipients: commentable.recipients }
end

That's what you want the bulk of the time. New comment creates a new Notification. But there may well be off cases, like copying a commentable and its comments, where you don't want that. So you'd have a concern something like this:

module Copyable
  def copy_to(destination)
    Notification.suppress do
      # Copy logic that creates new comments that we do not want
      # triggering notifications.
    end
  end
end