Creating a DSL inspired by the rspec assertions but with a conversion method thrown in for added semantic measure.

invite.rb

module Invite
  module_function
 
  def Invite(people)
    Invitees.new(people)
  end
 
  class Invitees
    attr_reader :recipients
    def initialize people
      @recipients = people.to_a
    end
 
    def to(event)
      recipients.each do |recipient|
        InvitationMailer.rsvp(event, recipient).deliver
      end
    end
  end
end
 
# You could use the long format:
Invite::Invitess.new(people).to(event)
 
# But the DSL is clearer
Invite(people).to(event)

# INTEGRATION POINT
class InvitationsController < ApplicationController
  include Invite

  # ...

  def create
    invitees = invitables.where(id: params[:invite_member_ids])
    event = events.first_by(id: params[:event_id])
    Invite(invitees).to(event)
    redirect_to event
  end
end