The Joy Of Ruby

The Joy of Ruby Clinton R. Nixon, Viget Labs

Ruby is designed to make programmers happy. – Yukihiro Matsumoto

Simplicity

a = "hello world" class String def no_vowels self.gsub(/[aeiou]/, '') end end p a.no_vowels # "hll wrld" Openness

Natural Language case year when 1800...1900 then "19th century" when 1900...2000 then "20th century" else "21st century" end "word".include? "a" 5.times do paint.stir! end color "orange blossom" do red 224 yellow 147 blue 22 end

An IntroducDon to Ruby

The Ruby Language Object-oriented Imperative Functional Dynamic Reﬂective

Basic Types Integer (Fixnum, Bignum) 8192 Float 3.14159 String "3.14159" Symbol :corndog Array ["gala", "fuji"] Hash {:plums => 2, :pears => 7} Boolean false

Object-‐Oriented 1.8.class # Float Array.new(["a", "b", "c"]) # ["a", "b", "c"] true.is_a?(Object) # true true.class # TrueClass true.methods # ["==", "===", "instance_eval", "freeze", "to_a",

Modules, Classes, and Objects module Authentication def valid_api_keys Database.retrieve_all_keys end def authenticated?(api_key) valid_api_keys.include? api_key end end class PublicAPI include Authentication def initialize(api_key) @api_key = api_key end def act if authenticated?(@api_key) do_a_thing end end end

Inheritance class PrivateAPI end include Authentication class PublicAPI def initialize(id, api_key) include Authentication @client = DB.get_client (id) def act @api_key = api_key if authenticated?(@api_key) end do_a_thing end def valid_api_keys end @client.api_keys end end class NewAPI < PublicAPI def act def act if authenticated? if authenticated?(@api_key) (@api_key) do_a_new_thing @client.do_a_thing end end end end end

The Inheritance Chain superclass Self Class Modules

Dynamic & Duck Typing It’s not what type of object you have It’s what that object can do

Duck Typing in AcDon class Rectangle < Struct.new(:width, :height) include Comparable def <=>(other) (self.width * self.height) <=> (other.width * other.height) end end r1 = Rectangle.new(4, 10) r2 = Rectangle.new(5, 7) r1 > r2 # => false

FuncDonal Ruby has broad support for functional programming But it’s not a functional language You could say it’s pragmatically functional

Blocks numbers = (1..10) numbers.map { |n| n * n } # => [1, 4, 9, 16, 25, 36, 49, 64, 81, 100] numbers.reduce { |total, n| total += n } # => 55 odd_test = proc { |n| n % 2 == 1 } numbers.select(&odd_test) # => [1, 3, 5, 7, 9] def before_save(&block) @before_callbacks << block end

First-‐class FuncDons def counter(x = 0) proc { x += 1 } end next_num = counter next_num.call # => 1 next_num.call # => 2 next_num.call # => 3 next_num.call # => 4 another_seq = counter(10) another_seq.call # => 11

First-‐class FuncDons def is_prime?(x) is_prime = proc do |n, m| if m > (n / 2) true elsif n % m == 0 false else is_prime.call(n, m + 1) end end is_prime.call(x, 2) if x >= 2 end (1..23).select { |n| is_prime?(n) } # => [2, 3, 5, 7, 11, 13, 17, 19, 23]

ReﬂecDon Struct.new (:AC, :THAC0).new.local_methods # => ["AC", "AC=", "THAC0", "THAC0=", # "[]", "[]=", "all?", "any?", ...] a = Rational(1, 2) a.instance_variables # => ["@denominator", "@numerator"] a.instance_variable_get("@numerator") # => 1

Metaprogramming module Accessors def access(var) define_method(var) do instance_variable_get("@#{var}") end define_method("#{var}=") do |val| instance_variable_set("@#{var}", val) end end end

Metaprogramming class Monster extend Accessors access :damage def initialize(damage) @damage = damage end end wampa = Monster.new("2d6") wampa.damage # => "2d6" wampa.damage = "1d12"

The Ruby Ecosystem

Rails, Rack, and Passenger

Merb Sinatra Ramaze Waves others Other Web Frameworks

Web deployment set :application, 'listy' set :repository, "git@github.com:viget/listyapp.git" set :scm, 'git' role :web, "listyapp.com" role :app, "listyapp.com" role :db, "listyapp.com", :primary => true set :user, "listy" set :deploy_to, "/home/listy/rails"

RubyGems Standard package management tool More like apt than CPAN Included with Ruby 1.9

Open Source The Ruby License is much like the MIT License. Most Ruby gems are under the Ruby license or MIT License. GitHub is the hub of most Ruby OS activity.

Other ImplementaDons JRuby IronRuby MacRuby and others

Ruby Shared Values

TesDng Rails was the ﬁrst framework I used that came with testing built in. Community has exploded in the last few years with testing tools. It’s rare I see a project without tests.

ConvenDon over ConﬁguraDon “The three chief virtues of a programmer are: Laziness, Impatience and Hubris.” – Larry Wall, who is not a Ruby programmer

Version Control Everyone should use version control, so this isn’t really a value. But Ruby programmers are fanatics for their VCS. Git is the VCS of choice. Being distributed, it allows for easy public forks of projects, which has helped OS in Ruby.

Sharing Ruby programmers have been chastised as self-promoters. I don’t see that as a bad thing. We share everything: open source code, discoveries, tips and tricks. Talk, talk, talk Blog, blog, blog

Passion I don’t know any Ruby programmers who aren’t excited about programming.

Why Ruby Was Right For Us (and Might Be Right For You)

O"en people, especially computer engineers, focus on the machines. They think, "By doing this, the machine will run faster. By doing this, the machine will run more eﬀec>vely. ..." They are focusing on machines. But in fact we need to focus on humans, on how humans care about doing programming or opera>ng the applica>on of the machines. – Matz TranslaDon: Ruby is not so fast.

ProducDvity Conventions and dynamism speed development. There are ridiculous quotes about “3-10x.” Personal observation: as a project goes on, it doesn’t get any harder, unlike other languages. Will testing slow you down?

Morale Anecdotally: people like to program in Ruby. Productive people are happier. Seeing instant results is very rewarding.

Broad UDlity Text processing Cross-platform GUI development: Monkeybars, Limelight, and Shoes Server conﬁguration management: Chef, Puppet, and Sprinkle Web servers: Mongrel, Unicorn, and Thin Testing other languages and anything else that isn’t matheletic

PlaYorm AgnosDc MRI runs on Windows, OS X, Linux, and most other Unixes. JRuby runs anywhere Java will run. IronRuby is going to make .NET awesome. Passenger works with Apache. But you can proxy through or use FastCGI from any web server, even IIS.

QuesDons

The Joy Of Ruby

by Clinton R. Nixon on Dec 29, 2009

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