Rails Magic Exposed - Speaker Deck

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Rails magic Saturday, August 11, 12

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(PPHMF 3FTVMUT Saturday, August 11, 12

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Framework Magic Total php (1994) 132000 2.527E+10 java (1995) 45900 960000000 .net (2002) 4400 250000000 django (2004) 9370 44300000 rails (2005) 7040 20300000 Saturday, August 11, 12

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.BHJD3BUJP w1)1 w+BWB w/&5 Saturday, August 11, 12

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.BHJD3BUJP w%KBOHP w3BJMT Saturday, August 11, 12

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0 1 2 3 4 php (1994) java (1995) .net (2002) django (2004) rails (2005) 0.052 0.478 0.176 2.115 3.468 Magic over Time Frequency / 10000 Saturday, August 11, 12

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0 1 2 3 4 php (1994) java (1995) .net (2002) django (2004) rails (2005) Node 0.052 0.478 0.176 2.115 3.468 2.031 A Step Back Saturday, August 11, 12

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0 100 200 300 400 php (1994) .net (2002) rails (2005) Meteor.js 0.052 0.478 0.176 2.115 3.468 2.031 345.810 MAGIC of Meteor Saturday, August 11, 12

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l"OZTVGpDJFOUMZ BEWBODFE UFDIOPMPHZJT JOEJTUJOHVJTIBCMF GSPNNBHJDz "SUIVS$$MBSL Saturday, August 11, 12

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dynamic finders Saturday, August 11, 12

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id = params[:customer_id] YourModel.find_by_customer_id id Saturday, August 11, 12

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def method_missing(method_id, *arguments) if match = /find_(all_by|by)_([_a-zA-Z]\w*)/. match(method_id.to_s) # find... elsif match = /find_or_create_by_([_a-zA-Z] \w*)/. match(method_id.to_s) # find_or_create... else super end end Saturday, August 11, 12

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magic columns Saturday, August 11, 12

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created_at and updated_at counter_caches type Saturday, August 11, 12

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def apply_it(items) items.map do |item| item.apply! if item.respond_to? (:apply!) end end Saturday, August 11, 12

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Active Record definition Saturday, August 11, 12

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class User < ActiveRecord::Base has_many :posts has_many :comments, through: :posts validates_presence_of :email end Saturday, August 11, 12

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class SuperWo 20.times {|i| puts "This is the #{i}”} def wat! puts "hi" end end SuperWo.new.wat! Try it out: http://rubyfiddle.com/riddles/a63dd Saturday, August 11, 12

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auto loading Saturday, August 11, 12

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Dir.glob('./app/models/*').each do |file| require file end require_relative 'db/setup' require_relative 'models/page' require_relative 'models/book' Saturday, August 11, 12

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# Extremely simple autoloading implementation class Module alias const_missing_without_autoloading const_missing def const_missing(const) path = “./#{name.gsub('::', '/')}/#{const}" path.gsub!(/([a-z\d])([A-Z])/,'\1_\2') require path.downcase const_defined?(const) ? const_get(const) : super rescue LoadError => error warn(error.message) super end end Saturday, August 11, 12

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class Foo @@foo ||= 42 puts @@foo # 42 end # reload... class Foo @@foo ||= 23 puts @@foo # 42 end Saturday, August 11, 12

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# reload... Object.send(:remove_const, :Foo) class Foo @@foo ||= 23 puts @@foo # 23 end Saturday, August 11, 12

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custom ruby Saturday, August 11, 12

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numbers = (1..100).to_a numbers.first numbers.last numbers.forty_two Saturday, August 11, 12

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def forty_two self[41] end "MTPLOPXOBTBDDFTTJOHUIF SFEEJU Saturday, August 11, 12

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class Enumerable def standard_dev Math.sqrt(sample_variance) end def sample_variance mean = sum.to_f / size.to_f sum{|i| (i-mean)**2} / size end end Saturday, August 11, 12