Intro To Advanced Ruby

Intro to Advanced Rubytwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

What makes Ruby special?twitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Its expressive 5.times do puts "Hello World" endtwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Its dynamic class Person [:first_name, :last_name, :gender].each do |method| attr_accessor method end endtwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Its extendable module KeywordSearch def find_all_by_keywords(keywords) self.where(["name like ?", "%" + keywords + "%"]) end end class Project < ActiveRecord::Base extend KeywordSearch end class Task < ActiveRecord::Base extend KeywordSearch endtwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Its ﬂexible def add(*args) args.reduce(0){ |result, item| result + item} end add 1,1,1,1twitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Its dangerous! class String def nil? self == "" end endtwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Our roadmap for today • Requiring ﬁles • Testing • Message passing • Classes vs Instances • Blocks and Lambdas • Monkeypatching • Modulestwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

requiretwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

require more functionality Date.today.to_s NoMethodError: undefined method today for Date:Class require date => true Date.today.to_s => "2011-04-09"twitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Testingtwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

A simple Unit test require test/unit class PersonTest < Test::Unit::TestCase def test_person_under_16_cant_drive p = Person.new p.age = 15 assert !p.can_drive? end endtwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Make it fail ﬁrst... Loaded suite untitled Started E Finished in 0.000325 seconds. 1) Error: test_person_under_16_cannot_drive(PersonTest): NameError: uninitialized constant PersonTest::Person method test_person_under_16_cannot_drive in untitled document at line 6 1 tests, 0 assertions, 0 failures, 1 errorstwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Now write the code class Person attr_accessor :age def can_drive? self.age >= 16 end endtwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

And pass the test! Loaded suite untitled Started . Finished in 0.00028 seconds. 1 tests, 1 assertions, 0 failures, 0 errorstwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Classes and Objects • A Ruby Class is an object of type Class • An Object is an instance of a Class • Classes can have methods just like objects • These are often used as static methods.twitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Instance vs class methods class Person class Person def sleep def self.sleep puts "ZZZZZZ" puts "ZZZZZZ" end end end end p = Person.new Person.sleep p.sleep "ZZZZZZ" "ZZZZZZ" => nil => niltwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Message passingtwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

.send class Person p = Person.new def name @name p.send(:name) end def name=(input) p.send(:name=, "Homer") @name = input end endtwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

We reduce complexity with this. class Sorter class Sorter def move_higher def move_higher puts "moved one higher" puts "moved one higher" end end def move_lower def move_lower puts "moved lower" puts "moved lower" end end def move(type) def move(type) case type self.send "move_" + type when "higher" then move_higher end when "lower" then move_lower end end end endtwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Then we can add more methods. class Sorter def move_higher puts "moved one higher" end def move_lower puts "moved lower" end def move_top puts "moved to the top" end def move_bottom puts "moved to the bottom" end def move(type) self.send "move_" + type end endtwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Send and respond_to class Person attr_accessor(:name) end p = Person.new p.send(:name) if p.respond_to?(:name) p.send(:age) if p.respond_to?(:age)twitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Blocks and Lambdastwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Blockstwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Encapsulation result = wrap(:p) do "Hello world" end puts result => "<p>Hello world</p>” def wrap(tag, &block) output = "<#{tag}>#{yield}</#{tag}>" endtwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

yield can bind objects! navbar = Navbar.create do |menu| menu.add "Google", "http://www.google.com" menu.add "Amazon", "http://www.amazon.com" end class Menu class Navbar def self.create(&block) def add(name, link) menu = Menu.new @items ||= [] yield menu @items << "<li><a href=#{link}>#{name}</a></li>" menu.to_s(options) end end end def to_s(options) menu = @items.join("n") "<ul>n#{menu}n</ul>" end endtwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Procs and Lambdastwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Delayed Execution a = lambda{|phrase| puts "#{phrase} at #{Time.now}" } puts a.call("Hello") sleep 1 puts a.call("Goodbye") Hello at Sat Apr 09 13:34:07 -0500 2011 Goodbye at Sat Apr 09 13:34:08 -0500 2011twitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Monkeypatchingtwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Reopen a class! class Object def blank? self.nil? || self.to_s == "" end def orelse(other) self.blank? ? other : self end endtwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Monkeypatching is an evil process!twitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Instead, we use Modulestwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Modules module OrElseMethods def blank? self.nil? || self.to_s == "" end def orelse(other) self.blank? ? other : self end endtwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

In Ruby, we don’t care about the type... we care about how the object works.twitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Including modules on objects module NinjaBehaviors def attack puts "Youve been killed silently!" end end class Person include NinjaBehaviors end p = Person.new p.attacktwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Extending classes with modules module NinjaCreator def new_ninja puts "Ive created a new Ninja" end end class Person extend NinjaCreator end Person.new_ninjatwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Person vs PersonNinjaRockStarAdmintwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Extending objects with modules module NinjaBehaviors def attack puts "Youve been killed silently!" end end module RockStarBehaviors def trash_hotel_room puts "What a mess!" end endtwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Extending objects with modules ninja = Person.new ninja.extend NinjaBehaviors ninja.attack rockstar = Person.new rockstar.extend RockStarBehaviors rockstar.trash_hotel_room rockstar.extend NinjaBehaviors rockstar.attacktwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Inject code without reopening! module OrElseMethods def blank? self.nil? || self.to_s == "" end def orelse(other) self.blank? ? other : self end end Object.send :include, OrElseMethodstwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

self.included class access module UserValidations def self.included(base) base.validates_presence_of :email, :login base.valudates_uniqueness_of :email, :login base.validates_confirmation_of :password end end class User < ActiveRecord::Base include UserValidations endtwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Modules can’t contain methods that overwrite existing methods!twitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

self.included + class_eval class Person module NoSave def save puts "Original save" def self.included(base) true base.class_eval do end def save end puts "New save" false end end end end Person.send :include, NoSavetwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Yes, that’s weird.twitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Putting it all together • Implement “before save” behavior - when we call “save” on our object, we want to declare other methods we want to hook in. class Person before_save, :foo, lambda{|p| p.name = "test"}, SuperFilter endtwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Demo https://github.com/napcs/intro_to_advanced_rubytwitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

Questions?twitter: bphoganemail: brianhogan at napcs.comhttp://spkr8.com/t/7114

http://speakerrate.com	27
http://coderwall.com	3
http://twitter.com	1

Intro To Advanced Ruby

by Brian Hogan on Apr 11, 2011

Accessibility

Categories

Tags

Upload Details

Usage Rights

3 Embeds 31

Statistics

Intro To Advanced Ruby — Presentation Transcript