The Rails Edge Day 1 - Sean Mountcastle

Recently, I attended The Rails Edge conference run by The Pragmatic Studio. It was a single track event with some of the best and brightest folks in the Rails and Ruby community. The speaker line-up was as follows:

Read on for a description of the first day’s sessions. After a brief welcome from Mike Clark, Dave Thomas launched the conference with his first session entitled “Metaprogramming Ruby: Extending Ruby for Fun and Profit.” He showed how classes were open by re-opening the String class and adding a method to encrypt the contents of the string and then he reimplemented the Rails modifications to Fixnum (so that 3.days.from_now works). He showed how code could be executed in the context of a class as that class was loaded (i.e. we could conditionally include/exclude methods in the class). Adding macros to Rails controllers was achieved using the Module.included method to detect when the Module was included in a controller and then perform some actions on that controller (such as adding methods to it). Next the power of eval and instance_eval was displayed—though he cautioned that eval’ing user input could be very dangerous. Finally, he showed how define_method could be used to create new methods on a controller like so:

~~~~ {lang=“ruby”} class ApplicationController < ActionController::Base def self.search_action_for(table_name)

model = table_name.to_s.classify.constantize
define_method("search_for_#{table_name}") do
  @title = "Your #{Inflector.humanize(table_name)}"
  @results = model.find(:all, :conditions => ["name like ?", "%#{params[:term]}%"])
  render :template => '/shared/search_results'
end

end end ~~~~

and you would use it like this:

~~{lang=“ruby”} class UsersController < ApplicationController search_action_for :users end~~

Following a short break, Mike Clark gave an overview of what’s new in Rails 1.2. Mike started off by listing the various virtual machines that are under development for Ruby, such as YARV, JRuby, Rubinius, RubyCLR, Cardinal, and smalltalk.rb. Then he went on to discuss migrations, plugins, rich models, parameter filtering, deprecations, integration test (a testing DSL), running Rails in headless mode (via the console), form_for, RJS, serialization, respond_to, named routes, CRUD/REST, syndication, ActiveResource, Mongrel, Capistrano, full-featured scaffold, Amazon S3, and Rinda/DRB. Next Stu gave his talk on Ruby Idioms for Rails Programmers. He covered the explicit API (which was Java code) and the implict API of today and how the implict API is implemented as many small modules included into big classes. Personalized Object Models (POM) were next, this is done by augmenting other people’s code, implementing DSLs with method-on-demand, using method_missing sparingly, and being domain specific. His presentation is available at CodeCite. Chad was up next with his talk on The Meaning of CRUD. This presentation went into the meaning of CRUD (Create, Read, Update, Destroy), RESTful routes and the SimplyHelpful plugin. This topic has been discussed at length elsewhere so I won’t go into the details. But Chad is always a great speaker and I enjoyed his presentation immensely. Following lunch there was a switch to the schedule as Jim Weirich hadn’t arrived yet. So Justin stepped up and gave his talk on Rails and Ajax. This presentation is also available online at CodeCite. Justin started off with a discussion of the Prototype JavaScript library with some simple examples, then launched into the various effects possible with Script.aculo.us. To wrap up, RJS was described along with JSON. This led nicely into Marcel’s talk on Reusing RJS. He started off by showing some duplicated RJS code into two actions within the same controller. For the first pass he tried extracting out a new private method with the duplicate code, but unfortunately it didn’t work since it was in the wrong scope. So he extracted it out to a helper and ensured that it could be passed the page object. This worked, but calling the new method looked really ugly (Marcel called this Pythonic). His next approach was to monkey patch JavaScriptGenerator right in Rails — invoking the new methods looked great, but he decided it wasn’t worth it to abuse method_missing plus it became a maintenance headache. So Marcel went back to the origins of RJS and explained some of the design choices that he and Sam made and reminded us that << just adds raw JavaScript to the stream. So he decided just to wrap update_page in the helper and then reuse the code with << like so:

~~~~ {lang=“ruby”} module ArticlesHelper def replace_article(article)

update_page do |page|
  page[article].replace :partial => article
  page.replace_html :controls, :partial => 'shared/controls'
end

end ~~~~

and then he reused it:

~~~~ {lang=“ruby”} def show

render :update do |page|
  page << replace_article(@article)
end

end def update

@article.update_attributes(params[:article])
render :update do |page|
  page << replace_article(@article)
  page.visual_effect :highlight, dom_id(@article)
end

end ~~~~

The great thing about this is that you can also reuse that JavaScript in your views as well:

{lang=“html”} Edit Article <% article_form(article) do |form| %> <%= render :partial => ‘articles/form’, : object => form %> <%= submit_tag ‘Save changes’ %> or <%= link_to_function ‘Cancel’, replace_article(article) %> <% end %>

After a short break, several conference attendees came up and demo’ed their apps. Some of the presenters were: Erik Hatcher who presented on his Solr.rb project (the acts_as_solr.rb plugin) and his work at UVA categorizing literature; Ryan Garver spoke about the AWS Console which makes it really easy to setup your server on Amazon Web Services EC2; Ken Collins spoke about Homemarks, simple project-based bookmarking, which he is open sourcing; Finally, someone from the FiveRuns team demo’ed their hosted systems management solution. While it certainly looks nice, I know my employer would never use it as it requires installing their software on your systems so it can report back to them. After dinner, Dave Thomas gave the opening keynote, entitled Fear of Flying. It was very good and I believe it was the same as the EuroRailsConf keynote that he gave, which is available online. Overall, the first day of The Rails Edge went very well and got me re-energized to work on my projects with several new ideas and a fresh perspective. I don’t think you can put a price on that.