Fractal Design

Given at the 2011 Ruby Hoedown

Transcript

1. Fractal Design Ben Scofield / @bscofield / bscofield@gmail.com 27 Aug 2011 / Ruby Hoedown
4. Fractals
5. Self-similarity
7. Simple, Repeated Rules
8. z = z + c n+1 n 2
9. z = z + c n+1 n 2
10. z = z + c n+1 n 2
12. Software
13. Methods def add_messages
 delivery_lists.each do |list_id|
 ponies = ponies_in_batches(:list_id => list_id)
 
 while ponies.any?
 create_messages_for_ ponies(ponies).each { |message| add_message(message) }
 ponies = ponies_in_batches(:last_id => ponies.last.id, :list_id => list_id)
 end
 end
 end

14. Classes class Pony
 def initialize(options = {})
 # ...
 end
 
 def prance
 # ...
 end
 
 # ...
 end

15. Libraries Gem::Specification.new do |s|
 s.name = %q{brohoof}
 s.version = "0.3.0"
 
 s.required_rubygems_version = Gem::Requirement.new(">= 0") if s.respond_to? ... s.authors = ["Rainbow Dash"]
 s.date = %q{2011-08-27}
 s.description = %q{Brohoof gives hoof-fives to your fellow bronies.}
 s.email = %q{brony@turrean.com}
 s.extra_rdoc_files = [
 "LICENSE.txt",
 "README.md"
 ]
 
 # ...
 end
16. Libraries Frameworks Tools
17. Applications # This file is used by Rack-based servers to start the application.
 
 require ::File.expand_path('../config/environment', __FILE__)
 run Celestia::Application

18. Applications Standalone Ecosystems
19. Data CREATE TABLE `cities` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `name` varchar(255) DEFAULT NULL,
 `created_at` datetime DEFAULT NULL,
 `updated_at` datetime DEFAULT NULL,
 `latitude` double DEFAULT NULL,
 `longitude` double DEFAULT NULL,
 `seo_name` varchar(255) DEFAULT NULL,
 `country_id` int(11) DEFAULT NULL,
 `inhabitants` int(11) NOT NULL DEFAULT '0',
 PRIMARY KEY (`id`),
 UNIQUE KEY `index_cities_on_seo_name` (`seo_name`),
 KEY `index_cities_on_country_id` (`country_id`),
 ) ENGINE=InnoDB AUTO_INCREMENT=100 DEFAULT CHARSET=utf8;
20. Tests class UnicornTest < ActiveSupport::TestCase
 test "unicorns should have magic" do
 trixie = Unicorn.new
 
 assert trixie.magical?
 end
 end
21. Insanity is doing the same thing over and over again but expecting different results
22. Context!
23. Principles
24. Examples
28. Test-Driven Design
29. Methods Unit testing
30. Systems Integration testing
31. Applications Acceptance testing
32. Database Changes class AddVelocityToPonies
 def self.up
 add_column :ponies, :max_velocity, :float
 end
 
 def self.down
 remove_column :ponies, :max_velocity
 end
 end
33. Single Responsibility Principle
34. Methods def plan_party(date)
 if is_a_good_day_for_a_party?(date)
 possible_venues = Venue.available_on(date)
 venue = possible_venues.first
 
 bands = Band.order('awesome DESC').all
 bands.each do |band|
 break if band.book(date)
 end
 
 buy_food
 
 invite_ponies(date, venue)
 end
 end
35. ActiveRecord::Base Persistence Business logic
36. Applications $ cat config/routes.rb | grep -c namespace
 7

37. Bitfields class AddPowersToPonies
 def self.up
 add_column :ponies, :powers, :int
 end
 
 def self.down
 remove_column :ponies, :powers
 end
 end Pony.powers << :magic
 Pony.powers << :flight
 
 # Time passes
 
 Pony.powers << :likes_to_plan_parties
 Pony.powers << :pink_mane
38. Interface Segregation Principle
39. Modules module PonyUtilities
 def comb_mane
 # ...
 end
 
 def cleanse_parasprites
 # ...
 end
 
 def expose_impostor
 # ...
 end
 end
40. Helpers $ ls app/helpers
 application_helper.rb
 authors_helper.rb
 categories_helper.rb
 comments_helper.rb
 posts_helper.rb
 tags_helper.rb
41. ActiveSupport require 'active_support/time'
 require 'active_support/ordered_hash' require 'active_support/core_ext/array'
 require 'active_support/core_ext/string'

42. JavaScript $ cat public/javascripts/application.js | wc -l
 7333
43. CSS $ cat public/stylesheets/base.css | wc -l
 1740
44. Dependency Inversion Principle
45. Mocks and Stubs test "a unicorn should be able to ask her friends for advice" do
 spike = stub(:name => 'Spike', :advice => "Keep trying!")
 twilight_sparkle = Unicorn.new
 twilight_sparkle.friends << spike
 
 assert_equal ['Spike: Keep trying!'], twilight_sparkle.ask_for_advice
 end
46. Libraries Context of use
47. App Ecosystems Services
48. Resource Orientation
49. Web Applications REST
50. Classes and Methods OOP
51. ...
52. Single Level of Abstraction
53. Methods def right_pony_for_the_job(pony, job)
 case job.class.name
 when 'Party': pony == PINKIE_PIE
 when 'Magic': pony.is_a?(Unicorn)
 when 'AnimalSoothing': pony == FLUTTERSHY
 when 'Flight': pony.can_fly?
 else false
 end
 end

54. Tests Behavior vs. implementation
55. Law of Demeter
56. Classes Fluttershy.pets.first.feed
 Fluttershy.pets.select { |pet| pet.devotion > 10 }.map(&:adopted_at)
57. App Ecosystems Enforced by APIs
58. Don’t Repeat Yourself
59. Methods Extract method
60. Classes Extract module
61. Libraries $ jeweler ponyville-police
62. Markup Generation Handlebars.js
63. Applications $ rails new friendship-magic
64. Asynchronicity
65. AJAX $.ajax('/friendship-lessons', {
 error: function(xhr, status, err) {
 // ...
 },
 success: function(data, status, xhr) {
 alert("Here's what I learned...");
 }
 });
66. Queuing
67. EventMachine class Orchard
 def initialize(owner)
 request = EM::HttpRequest.new('http://orchards.com').get
 
 request.callback {
 if request.response_header.status == 200
 data = JSON.parse(request.response)["responseData"]
 self.succeed data['ripe_apple_count']
 else
 self.fail("Orchard retrieval error")
 end
 }
 end
 end
 
 EM.run {
 orchard = Orchard.new('Applejack')
 orchard.callback { |count| puts "We’ve got #{count} ripe apples!" }
 }
68. On-Site Customer
69. Applications On-site customer
70. Libraries Client code Developers
71. RubyGems Library developers End developers
72. JavaScript Your mom
73. Can a given design principle be applied usefully at other levels of software design?
74. Questions?
75. Thank you! Ben Scofield / @bscofield / bscofield@gmail.com 27 Aug 2011 / Ruby Hoedown
76. Thank you! Ben Scofield / @bscofield / bscofield@gmail.com 27 Aug 2011 / Ruby Hoedown