Don't Repeat Yourself, Repeat Others

Transcript

1. Ordered List John Nunemaker RailsConf Baltimore, MD June 8, 2010 Repeat Others Don’t Repeat Yourself
2. Why?
3. Why? I am obsessed with improving
4. Why? I am obsessed with improving I have learned a lot of late
5. Why? I am obsessed with improving I have learned a lot of late I love sharing what I learn
6. Steal Think Create
7. Steal Think Create
8. “ Aristotle What we have to learn to do, we learn by doing.
9. Don’t Reinvent the Wheel.
10. Don’t Reinvent the Wheel.
11. “ Jason Sage Reinventing the wheel is as important to a developer’s education and skill as weightlifting is to a body builder. 97 Things Every Programmer Should Know
13. “ John Nunemaker The lessons learned and deeper appreciation for ActiveRecord and DataMapper alone was enough to make it worth it. RailsTips.org Comment
14. What Lessons? I am glad you asked.
15. Dynamic language is dynamic
16. autoload
17. # person.rb class Person; end # some_other_ruby_file.rb autoload Person, 'path/to/person' # as soon as Person class is used, # ruby requires the file person = Person.new # if it is not used, it is not required
18. module MongoMapper autoload :Document, 'mongo_mapper/document' autoload :EmbeddedDocument, 'mongo_mapper/embedded_document' autoload :Plugins, 'mongo_mapper/plugins' autoload :Version, 'mongo_mapper/version' module Plugins autoload :Associations, 'mongo_mapper/plugins/associations' autoload :Callbacks, 'mongo_mapper/plugins/callbacks' autoload :Clone, 'mongo_mapper/plugins/clone' autoload :Descendants, 'mongo_mapper/plugins/descendants' autoload :Dirty, 'mongo_mapper/plugins/dirty' end end
19. method missing
20. dynamic finders find_by_first_name
21. def method_missing(method, *args, &block) finder = DynamicFinder.new(method) if finder.found? dynamic_find(finder, args) else super end end
22. dirty keys name_changed?
23. def method_missing(method, *args, &block) if method.to_s =~ /(_changed\?|_change|_will_change!|_was)$/ method_suffix = $1 key = method.to_s.gsub(method_suffix, '') if key_names.include?(key) case method_suffix when '_changed?' key_changed?(key) when '_change' key_change(key) when '_will_change!' key_will_change!(key) when '_was' key_was(key) end else super end else super end end
24. class_eval, module_eval, etc.
25. class Person include MongoMapper::Document end
26. module MongoMapper module Document def self.included(model) model.class_eval do extend Plugins plugin Plugins::Associations plugin Plugins::Equality plugin Plugins::Inspect # etc... end end end end
27. class Activity include MongoMapper::Document key :source, Hash key :source_type, String key :action, String timestamps! end class Article include MongoMapper::Document key :title, String end
28. article = Article.create(:title => 'Yo Dawg') activity = Activity.create({ :source => article.to_mongo, :source_type => 'Article', :action => 'create' })
29. class Activity include MongoMapper::Document key :source, Hash key :source_type, String key :action, String timestamps! def source=(value) self.source_type = value.class.name super value.to_mongo end end
30. article = Article.create(:title => 'Yo Dawg') activity = Activity.create({ :source => article, :action => 'create' })
31. class Activity module MongoMapperKeys def source read_key :source end def source=(value) write_key :source, value end def source? read_key(:source).present? end end include MongoMapperKeys end
32. def create_accessors_for(key) accessors_module.module_eval <<-end_eval def #{key.name} read_key(:#{key.name}) end def #{key.name}_before_typecast read_key_before_typecast(:#{key.name}) end def #{key.name}=(value) write_key(:#{key.name}, value) end def #{key.name}? read_key(:#{key.name}).present? end end_eval include accessors_module end
33. def accessors_module if key_accessors_module_defined? const_get 'MongoMapperKeys' else const_set 'MongoMapperKeys', Module.new end end
34. Dynamic language is dynamic
35. Objects can do more than #new and #save
36. Equality
37. class Person attr_accessor :name def initialize(name) @name = name end end puts Person.new('John') == Person.new('John') # false puts Person.new('John').eql?(Person.new('John')) # false
38. class Person attr_accessor :name def initialize(name) @name = name end def eql?(other) self.class.eql?(other.class) && name == other.name end end puts Person.new('John') == Person.new('John') # false puts Person.new('John').eql?(Person.new('John')) # true
39. class Person attr_accessor :name def initialize(name) @name = name end def eql?(other) self.class.eql?(other.class) && name == other.name end alias :== :eql? end puts Person.new('John') == Person.new('John') # true puts Person.new('John').eql?(Person.new('John')) # true
40. Clone/dup
41. class OptionsHash attr_reader :source def initialize(source) @source = source end def [](key) @source[key] end def []=(key, value) @source[key] = value end end
42. hash1 = OptionsHash.new({:foo => 'bar'}) hash2 = hash1.clone puts hash1[:foo] # 'bar' hash2[:foo] = 'surprise' puts hash1[:foo] # 'surprise' puts hash1.source.equal?(hash2.source) # true
43. class OptionsHash def initialize_copy(other) super @source = @source.clone end end
44. class OptionsHash def initialize_copy(other) super @source = @source.clone end end hash1 = OptionsHash.new({:foo => 'bar'}) hash2 = hash1.clone puts hash1[:foo] # 'bar' hash2[:foo] = 'surprise' puts hash1[:foo] # 'bar' puts hash1.source.equal?(hash2.source) # false
45. Hooks
46. class Item def self.inherited(subclass) puts self.inspect puts subclass.inspect end end class Page < Item end # Item # Page
47. module MongoMapper module Plugins module Sci module ClassMethods def inherited(subclass) key :_type, String unless key?(:_type) unless subclass.embeddable? subclass.set_collection_name(collection_name) end super end end end end end
48. module Heyooooooooo def self.included(base) puts "Heyooooooooo!" end end class User include Heyooooooooo end # Heyooooooooo!
49. module MongoMapper module Document def self.included(model) model.class_eval do extend Plugins plugin Plugins::Associations plugin Plugins::Equality plugin Plugins::Inspect # etc... end end end end
50. Excercises for the Listener Validations, Callbacks, Comparable, Enumerable
51. Objects can do more than #new and #save
52. Patterns are not just for the enterprise
53. Proxy A class that is an interface to another class
54. class Proxy def initialize(source) @source = source end private def method_missing(method, *args, &block) @source.send(method, *args, &block) end end
55. class Proxy def initialize(source) @source = source end private def method_missing(method, *args, &block) @source.send(method, *args, &block) end end results = [1, 2, 3, 4] proxy = Proxy.new(results) puts proxy.size # 4 puts results.size # 4 puts proxy[2] # 3 puts results[2] # 3
56. Decorator New behavior to object dynamically
57. query = Plucky::Query.new(collection) docs = query.paginate(:per_page => 1) puts docs.class # Array puts docs.total_entries # 2 puts docs.total_pages # 2 puts docs.current_page # 1 puts [].total_pages # NoMethodError!
58. module Pagination def total_entries 50 end def total_pages 5 end end result = [1, 2, 3, 4] result.extend(Pagination) puts result.total_entries # 50 puts result.total_pages # 5
59. module Plucky class Query def paginate(opts={}) # some stuff paginator = Pagination::Paginator.new(total, page, limit) query[:limit] = paginator.limit query[:skip] = paginator.skip query.all.tap do |docs| docs.extend(Pagination::Decorator) docs.paginator(paginator) end end end end
60. require 'forwardable' module Plucky module Pagination module Decorator extend Forwardable def_delegators :@paginator, :total_entries, :total_pages, :current_page, :per_page, :previous_page, :next_page, :skip, :limit, :offset, :out_of_bounds? def paginator(p=nil) return @paginator if p.nil? @paginator = p self end end end end
61. Identity Map A man with two watches never knows the time
62. Excercises for the Listener Read Ruby Design Patterns
63. Patterns are not just for the enterprise
64. APIs or how to eat your own dog food
65. Powered by Plugins MongoMapper is associations, callbacks, clone, descendants, dirty, equality, identity_map, inspect, keys, logger, modifiers, pagination, persistence, protected, rails, serialization, timestamps, userstamps, validations
66. module MongoMapper module Plugins def plugins @plugins ||= [] end def plugin(mod) extend mod::ClassMethods if mod.const_defined?(:ClassMethods) include mod::InstanceMethods if mod.const_defined?(:InstanceMethods) mod.configure(self) if mod.respond_to?(:configure) plugins << mod end end end
67. module MongoMapper module Document def self.included(model) model.class_eval do extend Plugins plugin Plugins::Document plugin Plugins::Associations plugin Plugins::Clone plugin Plugins::Equality plugin Plugins::Indexes plugin Plugins::Keys # etc end super end end end
68. module ActsAsListFu module ClassMethods def reorder(ids) # reorder ids... end end module InstanceMethods def move_to_top # move to top end end def self.configure(model) model.key :position, Integer, :default => 1 end end
69. class Foo include MongoMapper::Document plugin ActsAsListFu end Foo.reorder(...) Foo.new.move_to_top
70. APIs or how to eat your own dog food
71. “ Mike Taylor I want to make things, not just glue things together. Whatever Happened to Programming
72. Steal Think Create
73. “ Pablo Picasso Good artists copy, great artists steal.
74. What Have I Stolen? I am glad you asked.
75. httparty
76. class Twitter include HTTParty base_uri 'twitter.com' end
77. module Scrobbler module REST class Connection def initialize(base_url, args = {}) @base_url = base_url @username = args[:username] @password = args[:password] end def get(resource, args = nil) request(resource, "get", args) end def post(resource, args = nil) request(resource, "post", args) end # removed to shorten... end end end
78. happymapper
79. class Status include HappyMapper element :id, Integer element :text, String element :created_at, Time element :source, String element :truncated, Boolean element :in_reply_to_status_id, Integer element :in_reply_to_user_id, Integer element :favorited, Boolean has_one :user, User end
80. August 9, 2008
81. November 17, 2008
82. mongomapper
83. plucky
84. gem whois
85. canable
86. “ John Nunemaker I steal.
87. What have I not stolen?
88. What have I not stolen?
89. Steal Think Create
90. Make decisions
91. class Account def add_user(user) user = user.is_a?(User) ? user : User.find(user) self.memberships << user.id end end
92. class Account def add_user(user) self.memberships << user.id end end
93. Extraction vs Prediction
94. Refactor
97. Write
99. Steal Think Create
100. Ordered List Thank you! john@orderedlist.com John Nunemaker RailsConf Baltimore, MD June 8, 2010 @jnunemaker