publishes_post.rb

class PublishesPost

  def self.call(*args)
    new(*args).call
  end

  attr_reader :post, :user

  def initialize(post, user)
    @post, @user = post, user
  end

  def call
    post.publish(user)
    send_notifications
  end

  private

  def send_notification
    # ...
  end

end

publishes_post2.rb

class PublishesPost

  def self.call(post, user)
    post.publish(user)
    PublicationMailer.deliver(post) # or whatever was inside .send_notifications
  end

end