First I looked at the Gemfile.lock. Had I known the format I would have found out my answer more quickly. I didn’t, though, and so when I found my first result for treetop, I stopped. It showed treetop below specs in the hierarchy.

GEM
  remote: http://rubygems.org/
  specs:
    # ...snip...
    thor (0.14.6)
    tilt (1.3.3)
    treetop (1.4.10)
      polyglot
      polyglot (>= 0.3.1)
    tzinfo (0.3.30)
    uglifier (1.0.3)

The next thing I did was run find . -iname '*.treetop' in ~/.rbenv. It found the following results:

(mbp) ~/.rbenv/versions/1.9.2-p290 $ find . -iname '*.treetop'
./lib/ruby/gems/1.9.1/gems/erector-0.8.3/lib/erector/erect/rhtml.treetop
./lib/ruby/gems/1.9.1/gems/mail-2.3.0/lib/mail/parsers/address_lists.treetop
./lib/ruby/gems/1.9.1/gems/mail-2.3.0/lib/mail/parsers/content_disposition.treetop
./lib/ruby/gems/1.9.1/gems/mail-2.3.0/lib/mail/parsers/content_location.treetop
./lib/ruby/gems/1.9.1/gems/mail-2.3.0/lib/mail/parsers/content_transfer_encoding.treetop
./lib/ruby/gems/1.9.1/gems/mail-2.3.0/lib/mail/parsers/content_type.treetop
./lib/ruby/gems/1.9.1/gems/mail-2.3.0/lib/mail/parsers/date_time.treetop
./lib/ruby/gems/1.9.1/gems/mail-2.3.0/lib/mail/parsers/envelope_from.treetop
./lib/ruby/gems/1.9.1/gems/mail-2.3.0/lib/mail/parsers/message_ids.treetop
./lib/ruby/gems/1.9.1/gems/mail-2.3.0/lib/mail/parsers/mime_version.treetop
./lib/ruby/gems/1.9.1/gems/mail-2.3.0/lib/mail/parsers/phrase_lists.treetop
./lib/ruby/gems/1.9.1/gems/mail-2.3.0/lib/mail/parsers/received.treetop
./lib/ruby/gems/1.9.1/gems/mail-2.3.0/lib/mail/parsers/rfc2045.treetop
./lib/ruby/gems/1.9.1/gems/mail-2.3.0/lib/mail/parsers/rfc2822.treetop
./lib/ruby/gems/1.9.1/gems/mail-2.3.0/lib/mail/parsers/rfc2822_obsolete.treetop
./lib/ruby/gems/1.9.1/gems/treetop-1.4.10/examples/lambda_calculus/arithmetic.treetop
./lib/ruby/gems/1.9.1/gems/treetop-1.4.10/examples/lambda_calculus/lambda_calculus.treetop
./lib/ruby/gems/1.9.1/gems/treetop-1.4.10/lib/treetop/compiler/metagrammar.treetop
./lib/ruby/gems/1.9.1/gems/treetop-1.4.10/spec/compiler/test_grammar.treetop
./lib/ruby/gems/1.9.1/gems/treetop-1.4.10/spec/compiler/test_grammar_do.treetop
./lib/ruby/gems/1.9.1/gems/treetop-1.4.10/spec/composition/a.treetop
./lib/ruby/gems/1.9.1/gems/treetop-1.4.10/spec/composition/b.treetop
./lib/ruby/gems/1.9.1/gems/treetop-1.4.10/spec/composition/c.treetop
./lib/ruby/gems/1.9.1/gems/treetop-1.4.10/spec/composition/d.treetop
./lib/ruby/gems/1.9.1/gems/treetop-1.4.10/spec/composition/f.treetop
./lib/ruby/gems/1.9.1/gems/treetop-1.4.10/spec/composition/subfolder/e_includes_c.treetop
(mbp) ~/.rbenv/versions/1.9.2-p290 $

Aha, so there are numerous treetop files in actionmailer! I have my answer. Seems like a good use of a parser, plus those may be worth using as examples.

Then I took another look at a Gemfile.lock from a rails project, and saw that it was plainly listed there. I just didn’t see it and didn’t keep looking after I found one.

GEM
  remote: http://rubygems.org/
  specs:
    XMLCanonicalizer (1.0.1)
      log4r (>= 1.0.4)
    actionmailer (3.1.1)
      actionpack (= 3.1.1)
      mail (~> 2.3.0)
  # ...snip...

I noticed something: Gemfile.lock doesn’t show an arbitrarily nested hierarchy; instead it shows a list of gems and their dependencies, where the list of gems includes all gems. Then, separately at the end of the file, it shows the top-level gems from the Gemfile.

To see a deeply nested, a graph could be constructed from the Gemfile.lock, using the two nesting levels under specs as an adjacency list.

While the JSON class has the two required methods, it doesn’t allow specifying a default. So I created a custom coder. I don’t know where the best file and module locations to put the class in are, so I won’t include them here. This is the class, though:

class JSONColumn
  def initialize(default={})
    @default = default
  end

  # this might be the database default and we should plan for empty strings or nils
  def load(s)
    s.present? ? JSON.load(s) : @default.clone
  end

  # this should only be nil or an object that serializes to JSON (like a hash or array)
  def dump(o)
    JSON.dump(o || @default)
  end
end

Since load and dump are instance methods, an instance of JSONColumn needs to be passed rather than the class. Here’s an example that works for me inside of the rails console:

class Person < ActiveRecord::Base
  validate :name, :pets, :presence => true
  serialize :pets, JSONColumn.new([])
end

Update: Added .clone to the load method. HT @miyagawa.

PeepCode

Pricing: Starts at $12 for one screencast; Twitter: @peepcode and @topfunky

I bought my first PeepCode screencast back in 2008, before Rails and Merb merged. It’s been around for a while, but Geoffrey Grosenbach does a great job of keeping it up-to-date. There are now a number of screencasts about current topics of interest to the Ruby on Rails community, including Rails 3, Backbone.js, PostgreSQL, CoffeeScript, and John Barnette.

Railscasts

Pricing: Free weekly episodes, additional weekly episodes and revised episodes for $9/mo (RailsCasts Pro); Twitter: @railscasts

Railscasts is great for keeping up on Ruby On Rails, and because it’s free, it’s also great for recommending to people who are curious about Rails but not ready to spend money to help them learn it. Ryan Bates is great at explaining things. He covers a wide variety of topics in his screencasts and presents them in a nice format with code snippets.

Update: since I posted this Ryan Bates released Railscasts Pro, which is fantastic!

Ruby on Rails Tutorial

Pricing: $26 (book), $85 (screencasts), $95 (both); Twitter: @railstutorial

Michael Hartl is a physicist who does a number of other things (see his about page) including Web Development with Ruby On Rails. I’ve watched all of his screencasts; they’re fantastic. He builds a web application TDD-style and teaches many different concepts including MVC and how TDD can help with authorization (which is trickier than authentication IMO).

Rails Apps

Pricing: Free; Twitter: @rails_apps

I always thought that the Rails Starter App templates were cool, but they were missing something: in-depth tutorials and a comparison between the many different templates and quick-start tools. Daniel Kehoe has provided both and many more useful resources in his Rails Apps GitHub account.

Code School

Pricing: Free (one substantial free product), $45-55 (single paid products); Twitter: @codeschool

Code School is a set of tutorials designed to help developers to quickly get up to speed building web applications. Gregg Pollack and Envy Labs have been doing podcasts and screencasts for quite some time, and it’s not surprising that they still do it, because they’re very enthusiastic in front of a camera and a microphone.

Today I went back to working without scaffolds. Since I’ve been trying to read the documentation as little as possible while developing, I had to figure some things out for myself. One thing I had to think of was the list of actions to type when generating a controller. Here is what I came up with:

script/generate controller Planets index new show edit create update destroy

I’m obsessive-compulsive, so not only did I try to remember what actions are used in scaffolds, I tried to put them in an order that makes sense to me. I put index first because index is special. After that, there were two sensible approaches I could think of to order the remaining actions. I could either order by CRUD or order by whether or not the actions have views. Either way, I would use the other ordering technique within groups. I went with ordering first by whether or not actions have views, and then by CRUD. I started with the actions that have views because it’s nice to have them at the top when jumping from a view to its controller.

Here’s my thought process in a tabular format:

Notice that there are a couple of holes in the table. The first one (*) is missing because the interface for deleting is built into the index. It doesn’t have to be this way, and in fact varies widely on the web. It could have its own page, or it could be on the show or even edit page (Side note: I think it’s bad UI to put the delete button on the edit page because the edit form doesn’t fit into the workflow of deleting an item. The user may want to look at an item before deleting it to make sure it’s something they don’t need, but they’re unlikely to want to edit an item). The second one (**) is missing because in the simple case reading is achieved entirely through GET requests.

One thing that’s convenient about having the ones without views at the end is that it makes it easy for me to remember which skeleton views to delete after running the generate command. It’s the last three.

It used to take me a minute or a few to remember what actions I need, but now that I have this mnemonic it should only take a few seconds.

Now, I place a certain level of importance on conventions. After I came up with this mnemonic I looked at a scaffold to see how rails orders things. The only difference between my ICRUDCRUD ordering (index, CRUD with views, CRUD without) or ICRUCUD ordering and the standard scaffold ordering is that the show and new actions are swapped. So rails uses the RCUD ordering. Fair enough. I have pontificated on whether the ordering in CRUD makes sense or is a bacronym. Create and read are pretty useless without eachother. Below is the table with the RCUD ordering. I threw index into the empty cell. If you read the first line left to right, then move down, like a book, the order is the same as it is in a scaffold:

Now, how to remember RCUD? Well, remembering to swap C and R is one way, but I prefer to think of a Rails cow chewing its CUD.

Original image from cerulean5000 on flickr. Used by Creative Commons license.

First, I asked them what would happen with slices in Rails 3. They explained that slices are going away in future versions of Rails and Merb, but the functionality will still be there. Instead of having slices, applications will simply be “mountable” within other applications.

I then asked if components such as models could be shared between slices. Yehuda said that their goal was to give all applications a namespace by default. He then went on to say that hopefully there will be no need to refer to an application’s namespace from within the application.

This sounds great! With a few contributions from the community, it should be at least as easy to install multiple apps into a site and get them sharing stuff as it currently is in Django.