The  Joy  of  Ruby

Clinton  R.  Nixon,  Viget  Labs

Ruby  is  designed  to  make  programmers  

happy.  –  Yukihiro  Matsumoto

Simplicity

Openness

a = "hello world"

class String def no_vowels self.gsub(/[aeiou]/, '') endend

p a.no_vowels # "hll wrld"

Natural  Language

case yearwhen 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 22end

An  IntroducDon  to  Ruby

The  Ruby  Language

Object-oriented

Functional Dynamic

Reflective

Imperative

Basic  TypesInteger (Fixnum, Bignum)

Float

String

Symbol

Array

Hash

Boolean

8192

3.14159

"3.14159"

:corndog

["gala", "fuji"]

{:plums => 2, :pears => 7}

false

Object-­‐Oriented

1.8.class # Float

Array.new(["a", "b", "c"]) # ["a", "b", "c"]

true.is_a?(Object) # truetrue.class # TrueClasstrue.methods # ["==", "===", "instance_eval", "freeze", "to_a",

Modules,  Classes,  and  Objectsmodule Authentication def valid_api_keys Database.retrieve_all_keys end def authenticated?(api_key) valid_api_keys.include? api_key endend

class PublicAPI include Authentication def initialize(api_key) @api_key = api_key end def act if authenticated?(@api_key) do_a_thing end endend

Inheritanceclass PrivateAPI include Authentication def initialize(id, api_key) @client = DB.get_client(id) @api_key = api_key end def valid_api_keys @client.api_keys end def act if authenticated?(@api_key) @client.do_a_thing end end

end

class PublicAPI include Authentication def act if authenticated?(@api_key) do_a_thing end endend

class NewAPI < PublicAPI def act if authenticated?(@api_key) do_a_new_thing end endend

The  Inheritance  Chain

Self Class Modules

superclass

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

Blocksnumbers = (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 << blockend

First-­‐class  FuncDonsdef counter(x = 0) proc { x += 1 }end

next_num = counternext_num.call # => 1next_num.call # => 2next_num.call # => 3next_num.call # => 4

another_seq = counter(10)another_seq.call # => 11

First-­‐class  FuncDonsdef 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 >= 2end (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 endend

Metaprogramming

class Monster extend Accessors access :damage def initialize(damage) @damage = damage endend

wampa = Monster.new("2d6")wampa.damage # => "2d6"wampa.damage = "1d12"

The  Ruby  Ecosystem

Rails,  Rack,  and  Passenger

Other  Web  Frameworks

Merb

Sinatra

Ramaze

Waves

others

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

JRubyIronRubyMacRubyand 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.

ProducDvityConventions 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  UDlityText 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