My try at a good presenter pattern with rails

application_helper.rb

module ApplicationHelper

  def present(model, items = {})
    name = model.is_a?(String) ? model : model.class.model_name.underscore

    items.merge!(name.to_sym => model) unless model.is_a?(String)

    "#{name.classify}Presenter".constantize.new(controller, items) do |presenter|
      yield(presenter) if block_given?
    end
  end

end

application_presenter.rb

class ApplicationPresenter
  include ActionView::Helpers
  include Rails.application.routes.url_helpers

  class << self
    delegate :model_name, :to => :model
  end

  def self.model
    @model ||= model_klass
  end
  
  def self.model_klass
    self.name.gsub(/Presenter/, '').constantize
  end

  attr_reader :controller
  
  def initialize(con, items = {})
    @controller = con

    items.each do |item_name, item|
      send(:"#{item_name}=", item)
    end

    yield(self) if block_given?
  end

end

index.html.erb

<ul>
  <% @posts.each do |post_model| %>
    <% present(post_model) do |post| %>
      <li><%= post.title_link %></li>
    <% end %>
  <% end %>
</ul>

post_presenter.rb

class PostPresenter < ApplicationPresenter
  attr_accessor :post
  delegate :id, :to_param, 
           :to => :post

  def title_link
    raw link_to(h(post.title), post)
  end

end