Don't.

We all know that intelligent species learn from mistakes, right?

There’s just one problem: Life is too short to make every possible mistake! Also, some mistakes are more costly than others. What’s the ambitious learner to do? I’m glad you asked! I’m an expert at making mistakes, and I’m happy to share as many of them as I can possibly fit into a 45-minute time slot with you, my dear conference attendee!

We’ll discuss a variety of exciting mistakes, ranging from the misapplication of metaprogramming techniques to letting emotions become barriers to new technologies to why it’s a horrible idea to stretch a gel keyboard wrist rest across a room, even if it seems like an awesome plan at the time.

Transcript

1. Don’t. @erniemiller Ernie Miller http://erniemiller.org
4. I HAVE DONE A LOT OF STUPID THINGS
5. Real Talk
6. Real Talk
7. Real Talk
8. Real Talk
12. …overestimate how much time you have Don’t...
18. …overestimate how much time you have Don’t...
25. Potential Energy
26. Potential Energy FOR BUSINESS!
35. …forget your choices have consequences Don’t...
36. Metaprogramming
40. DERP
41. Rules for Class Macros What, not how! Idempotent! Order independent! Straightforward! Free of branching 1 2 3 4 5
42. def self.included(base) base.extend ClassMethods ! base.class_eval do class_attribute :_metasearch_include_attributes, :_metasearch_exclude_attributes class_attribute :_metasearch_include_associations, :_metasearch_exclude_associations class_attribute :_metasearch_methods self._metasearch_include_attributes = self._metasearch_exclude_attributes = self._metasearch_exclude_associations = self._metasearch_include_associations = {} self._metasearch_methods = {} end end
43. def attr_unsearchable(*args) if table_exists? opts = args.extract_options! args.flatten.each do |attr| attr = attr.to_s unless self.columns_hash.has_key?(attr) raise(ArgumentError, "No persisted attribute (column) named #{attr} in #{self}”) end self._metasearch_exclude_attributes = self._metasearch_exclude_attributes.merge( attr => { :if => opts[:if] } ) end end end
44. def attr_searchable(*args) if table_exists? opts = args.extract_options! args.flatten.each do |attr| attr = attr.to_s unless self.columns_hash.has_key?(attr) raise(ArgumentError, "No persisted attribute (column) named #{attr} in #{self}”) end self._metasearch_include_attributes = self._metasearch_include_attributes.merge( attr => { :if => opts[:if] } ) end end end
45. def assoc_unsearchable(*args) opts = args.extract_options! args.flatten.each do |assoc| assoc = assoc.to_s unless self.reflect_on_all_associations.map {|a| a.name.to_s}.include?(assoc) raise(ArgumentError, "No such association #{assoc} in #{self}”) end self._metasearch_exclude_associations = self._metasearch_exclude_associations.merge( assoc => { :if => opts[:if] } ) end end
46. def assoc_searchable(*args) opts = args.extract_options! args.flatten.each do |assoc| assoc = assoc.to_s unless self.reflect_on_all_associations.map {|a| a.name.to_s}.include?(assoc) raise(ArgumentError, "No such association #{assoc} in #{self}”) end self._metasearch_include_associations = self._metasearch_include_associations.merge( assoc => { :if => opts[:if] } ) end end
47. class Article < ActiveRecord::Base attr_searchable :some_public_data, :some_more_searchable_stuff assoc_searchable :search_this_association_why_dontcha end
48. def ransackable_attributes(auth_object = nil) column_names + _ransackers.keys end ! def ransackable_associations(auth_object = nil) reflect_on_all_associations.map { |a| a.name.to_s } end
49. …fall in love with metaprogramming Don’t...
50. …fall in love with metaprogramming Don’t...
51. …fall in love with metaprogramming Don’t...
52. YOU CAN NOT HAS BUCKET OF METHODS if Class < Module puts 'That goes for you too, Class.' end
53. module MetaSearch module Utility #:nodoc: ! TRUE_VALUES = [true, 1, '1', 't', 'T', 'true', 'TRUE'].to_set FALSE_VALUES = [false, 0, '0', 'f', 'F', 'false', 'FALSE'].to_set ! private ! def preferred_method_name(method_id) method_name = method_id.to_s where = Where.new(method_name) rescue nil return nil unless where where.aliases.each do |a| break if method_name.sub!(/#{a}(=?)$/, "#{where.name}\\1") end method_name end ! def array_of_strings?(o) o.is_a?(Array) && o.all?{|obj| obj.is_a?(String)} end ! def array_of_arrays?(vals) vals.is_a?(Array) && vals.first.is_a?(Array) end ! def array_of_dates?(vals) vals.is_a?(Array) && vals.first.respond_to?(:to_time) end ! def cast_attributes(type, vals) if array_of_arrays?(vals) vals.map! {|v| cast_attributes(type, v)} # Need to make sure not to kill multiparam dates/times elsif vals.is_a?(Array) && (array_of_dates?(vals) || !(DATES+TIMES).include?(type)) vals.map! {|v| cast_attribute(type, v)} else cast_attribute(type, vals)
54. when :integer val.blank? ? nil : val.to_i when :float val.blank? ? nil : val.to_f when :decimal if val.blank? nil elsif val.class == BigDecimal val elsif val.respond_to?(:to_d) val.to_d else val.to_s.to_d end else raise TypeCastError, "Unable to cast columns of type #{type}" end end ! def collapse_multiparameter_options(opts) opts.keys.each do |k| if k.include?("(") real_attribute, position = k.split(/\(|\)/) cast = %w(a s i).include?(position.last) ? position.last : nil position = position.to_i - 1 value = opts.delete(k) opts[real_attribute] ||= [] opts[real_attribute][position] = if cast (value.blank? && cast == 'i') ? nil : value.send("to_#{cast}") else value end end end opts end end end
55. …put your code in “buckets” Don’t...
57. …hitch your cart to someone else’s horse Don’t...
58. MediaWiki schema, image by Nick Jenkins
60. …think of your app as “a Rails app” Don’t...
61. require 'delegate' ! class Auditor < SimpleDelegator attr_reader :user, :record ! def initialize(user, record) @user, @record = user, record super(record) end ! def class @record.class end ! def update_attributes(attributes, options = {}) with_transaction_returning_status do assign_attributes(attributes, options) save end end ! def save(*) action = @record.persisted? ? 'update' : 'create' super.tap { |success| success && log_action(action) } end ! def destroy super.tap { |record| record && log_action('destroy') } end ! # ... ! end
62. require 'delegate' ! class Auditor < SimpleDelegator attr_reader :user, :record ! def initialize(user, record) @user, @record = user, record super(record) end ! def class @record.class end ! def update_attributes(attributes, options = {}) with_transaction_returning_status do assign_attributes(attributes, options) save end end ! def save(*) action = @record.persisted? ? 'update' : 'create' super.tap { |success| success && log_action(action) } end ! def destroy super.tap { |record| record && log_action('destroy') } end ! # ... ! end
63. def render(&block) options = @options.stringify_keys tag_value = options.delete("value") name_and_id = options.dup ! if name_and_id["for"] name_and_id["id"] = name_and_id["for"] else name_and_id.delete("id") end ! add_default_name_and_id_for_value(tag_value, name_and_id) options.delete("index") options.delete("namespace") options["for"] = name_and_id["id"] unless options.key?("for") ! if block_given? content = @template_object.capture(&block) else content = if @content.blank? @object_name.gsub!(/\[(.*)_attributes\]\[\d+\]/, '.\1') method_and_value = tag_value.present? ? "#{@method_name}.#{tag_value}" : @method_name ! if object.respond_to?(:to_model) key = object.class.model_name.i18n_key i18n_default = ["#{key}.#{method_and_value}".to_sym, ""] end ! i18n_default ||= "" I18n.t("#{@object_name}.#{method_and_value}", :default => i18n_default, :scope => "helpers.label").presence else @content.to_s end ! content ||= if object && object.class.respond_to?(:human_attribute_name) object.class.human_attribute_name(@method_name) end ! content ||= @method_name.humanize end ! label_tag(name_and_id["id"], content, options) end action_view/helpers/tags/label.rb
64. def render(&block) options = @options.stringify_keys tag_value = options.delete("value") name_and_id = options.dup ! if name_and_id["for"] name_and_id["id"] = name_and_id["for"] else name_and_id.delete("id") end ! add_default_name_and_id_for_value(tag_value, name_and_id) options.delete("index") options.delete("namespace") options["for"] = name_and_id["id"] unless options.key?("for") ! if block_given? content = @template_object.capture(&block) else content = if @content.blank? @object_name.gsub!(/\[(.*)_attributes\]\[\d+\]/, '.\1') method_and_value = tag_value.present? ? "#{@method_name}.#{tag_value}" : @method_name ! if object.respond_to?(:to_model) key = object.class.model_name.i18n_key i18n_default = ["#{key}.#{method_and_value}".to_sym, ""] end ! i18n_default ||= "" I18n.t("#{@object_name}.#{method_and_value}", :default => i18n_default, :scope => "helpers.label").presence else @content.to_s end ! content ||= if object && object.class.respond_to?(:human_attribute_name) object.class.human_attribute_name(@method_name) end ! content ||= @method_name.humanize end ! label_tag(name_and_id["id"], content, options) end action_view/helpers/tags/label.rb
65. if object.respond_to?(:to_model) key = object.class.model_name.i18n_key i18n_default = ["#{key}.#{method_and_value}".to_sym, ""] end
66. if object.respond_to?(:to_model) key = object.class.model_name.i18n_key i18n_default = ["#{key}.#{method_and_value}".to_sym, ""] end (more like LOL of Demeter, amirite?)
67. class PostsController < ApplicationController ! # ... ! def edit @post = Auditor.new(current_user, Post.find(params[:id])) end ! # ... ! end <%= link_to 'Comments', post_comments_path(@post) %>
68. class PostsController < ApplicationController ! # ... ! def edit @post = Auditor.new(current_user, Post.find(params[:id])) end ! # ... ! end <%= link_to 'Comments', post_comments_path(@post) %> /posts/1/comments/?post_id=1
69. def generate key, name, options, recall = {}, parameterize = nil constraints = recall.merge options ! match_route(name, constraints) do |route| data = constraints.dup ! keys_to_keep = route.parts.reverse.drop_while { |part| !options.key?(part) || (options[part] || recall[part]).nil? } | route.required_parts ! (data.keys - keys_to_keep).each do |bad_key| data.delete bad_key end ! parameterized_parts = data.dup ! if parameterize parameterized_parts.each do |k,v| parameterized_parts[k] = parameterize.call(k, v) end end ! parameterized_parts.keep_if { |_,v| v } ! next if !name && route.requirements.empty? && route.parts.empty? ! next unless verify_required_parts!(route, parameterized_parts) ! z = Hash[options.to_a - data.to_a - route.defaults.to_a] ! return [route.format(parameterized_parts), z] end ! raise Router::RoutingError end
70. def generate key, name, options, recall = {}, parameterize = nil constraints = recall.merge options ! match_route(name, constraints) do |route| data = constraints.dup ! keys_to_keep = route.parts.reverse.drop_while { |part| !options.key?(part) || (options[part] || recall[part]).nil? } | route.required_parts ! (data.keys - keys_to_keep).each do |bad_key| data.delete bad_key end ! parameterized_parts = data.dup ! if parameterize parameterized_parts.each do |k,v| parameterized_parts[k] = parameterize.call(k, v) end end ! parameterized_parts.keep_if { |_,v| v } ! next if !name && route.requirements.empty? && route.parts.empty? ! next unless verify_required_parts!(route, parameterized_parts) ! z = Hash[options.to_a - data.to_a - route.defaults.to_a] ! return [route.format(parameterized_parts), z] end ! raise Router::RoutingError end
71. …assume too much about how others will use your objects Don’t...
72. def eql?(other) self.class == other.class && self.user == other.user && self.record == other.record end alias :== :eql?
74. …use ActiveRecord callbacks, if you can help it Don’t...
75. …use ActiveRecord callbacks, if you can help it Don’t... (you can almost always help it)
76. before_save!!! class User < ActiveRecord::Base def create_or_update say_my_name && super end ! def say_my_name puts "My name is #{name}"; true end end
77. before_save!!! class User < ActiveRecord::Base def create_or_update say_my_name && super end ! def say_my_name puts "My name is #{name}"; true end end
78. after_save!!! class User < ActiveRecord::Base def create_or_update super && final_stuff or raise ActiveRecord::Rollback end ! def final_stuff puts "IMPORTANT FINAL STUFF" end end
79. after_save!!! class User < ActiveRecord::Base def create_or_update super && final_stuff or raise ActiveRecord::Rollback end ! def final_stuff puts "IMPORTANT FINAL STUFF" end end
80. around_save!!! class User < ActiveRecord::Base def create_or_update puts "GET READY" unless sneak_attack? super puts "WASN'T THAT EXCITING?" if awesome? end end
81. around_save!!! class User < ActiveRecord::Base def create_or_update puts "GET READY" unless sneak_attack? super puts "WASN'T THAT EXCITING?" if awesome? end end
84. Me (sort of)
85. …mistake the illusion of accomplishment for the real thing Don’t...
86. Photo by Tim Baker http://www.flickr.com/photos/timmygunz/
87. …accept! counter-offers Don’t...
89. …take a job for the money Don’t...
92. Photo by Robbert van der Steeg
93. …assume it’s too late Don’t...
95. …get comfortable Don’t...
99. Not me.
100. Not me. Also not me.
101. Stepdaughter, clearly acknowledging my coolness.
104. …try to be someone you’re not Don’t...
106. …be afraid Don’t...
108. …be afraid to say no Don’t...
109. Philippe Faraut, “La Fille du Marin”
111. Employee.where(:slacker => true).values_of :first_name, :last_name, :hired_at # => [["Ernie", "Miller", 2009-09-21 08:00:00 -0400], ...] ! class Animal < ActiveRecord::Base serialize :extra_info end ! Animal.where(:genus => 'felis').values_of :species, :extra_info # => [["catus", {:domestic => true}], ["lolcatus", {:can_has_cheezburger => true}], ...] Valium https://github.com/ernie/valium
112. “I've had times where I would just fork off a child process, do all the memory-intensive stuff inside the child process (1000+ AR objects would be instantiated) and then kill off the child when it was finished to remove potential memory leaks.” — A commenter
118. …be afraid to share Don’t...
120. …be afraid to speak Don’t...
122. SEEK ACCOUNTABILITY
124. …be afraid to stretch Don’t...
125. THANKS!
126. ❤️ THANKS!