peter

# 0. Make sure you have Ruby 1.9.3 installed, and optionally RVM and PostgreSQL

# 0.2 If you are on the Mac, make sure you have a c compiler by installing XCode Command Line Tools or gcc4.2 with homebrew
# https://github.com/mxcl/homebrew/wiki/Custom-GCC-and-cross-compilers

# 0.5 Make sure you have bundler version ~> 1.2 as Rails depends on it
gem install bundler

# 1. Get edge Rails source (master branch)
git clone https://github.com/rails/rails.git

peter

def counts_from_dice(dice)
  dice.inject({}) do |hash, value|
    hash[value] ||= 0
    hash[value] += 1
    hash
  end
end

def score(dice)
  counts_from_dice(dice).inject(0) do |sum, (number, count)|    

peter

# Traditional idiom
total = 1
[2, 3, 5].each do |value|
  total = total * value
end
puts total

# Ruby idiom
puts [2, 3, 5].inject { |mult, value| mult * value }

peter

module NullifyTextAttributes
  def self.included(base)
    base.class_eval do
      before_validation :nullify_text_attributes

      private
      def nullify_text_attributes
        self.class.columns.select { |c| [:text, :string].include?(c.type) }.each do |column|
          send("#{column.name}=", nil) if read_attribute(column.name).blank?
        end

peter

class ImportLegacyDevices < ActiveRecord::Migration
  def self.up
    return unless Rails.env.production?

    legacy_devices.each do |device_id, issue|
      if device = Device.find_by_hardware_id(device_id)
        unless InclusiveIssue.exists?(:issue_id => issue.id, :device_id => device.id)
          InclusiveIssue.create!(
            :issue => issue,
            :device => device,

peter

require 'rubygems'
require 'debug_log'

my_list = [:a, :b, :c]
my_number = 5
debug.log("after variable initialization", "my_number", "my_list")
# => DebugLog | after variable initialization | my_number="5" (Fixnum), my_list="[:a, :b, :c]" (Array) | /Users/peter/tmp/debug-example.rb:6:in `foo'

peter

# In spec_helper.rb or test_helper.rb:
Mocha::Configuration.prevent(:stubbing_non_existent_method)

module MochaExtensions
  module ObjectMethods
    def expects_message(*args, &block)
      Mocha::Configuration.allow(:stubbing_non_existent_method) { expects(*args, &block) }
    end

    def stubs_message(*args, &block)

peter

# Notes on migrating from the RSpec builtin mocking framework to the Mocha framework

# 1. Comment in this line in spec_helper.rb:
config.mock_with :mocha

# 2. Specify your gem dependency (optional) in config/environments/test.rb:
config.gem "mocha", :version => "0.9.8"

# 3. Use query-replace to do most but not all of the DSL conversion
# should_receive -> expects

peter

-- Order by one indexed column (FAST)
newsdesk_production=# explain analyze select * from pressreleases order by published_at DESC limit 100;
                                                                                   QUERY PLAN                                                                                    
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=0.00..249.91 rows=100 width=1207) (actual time=26.070..716.453 rows=100 loops=1)
   ->  Index Scan Backward using pressreleases_published_at_index on pressreleases  (cost=0.00..964766.62 rows=386042 width=1207) (actual time=26.067..716.343 rows=100 loops=1)
 Total runtime: 716.709 ms
(3 rows)

- Order by two separately indexed columns (SLOW)

peter

# => SELECT "posts".* FROM "posts" ORDER BY published DESC, id DESC LIMIT 1
Post.send(:with_scope, {:find => {:order => "id DESC"}}) do
  Post.first(:order => "published DESC")
end