presents.rb

class ApplicationController < ActionController::Base
  def self.present as, from, klass
    if from.to_s.singularize == from.to_s
      expose(as) { klass.new send(from) }
    else
      expose(as) { send(from).map { |orig| klass.new(orig) } }
    end
  end
end

# In another controller...

expose(:people)
present(:pretty_people, :people, PrettyPeoplePresenter)

# In your view

- pretty_people.each do |pretty|
  render :pretty_pretty, pretty