the ruby idiom

The Ruby Idiom

Ben Hughes@rubiety

http://benhugh.es

Friday, April 22, 2011

“Ruby is designed to make

programmers happy” - Matz

Aesthetic EleganceVery IdiomaticLoose Syntax

Extremely DynamicExpressive

Blocks

people.each do |person| puts person.nameend

1.upto(10) do |i| puts "Counting #{i}"end

5.times { puts "Hello" }

open "people.txt" do |file| file.each_line do |line| puts line.split(",").first endend

users.select {|u| u.age >= 21}.map(&:name).sort

class Personend

Person.class # => Class

nil.class # => NilClasstrue.class # => TrueClass

Open Classes

class String def blank? self == "" endend

class Numeric def seconds self end def minutes self * 60 end def hours self * 3600 end def from_now Time.now + self endend

12.hours.from_now

2.minutes + 30.seconds

4 + 2 # => 2

# Yes, Be Evil:class Numeric def +(another) self - another endend

Executable Declarations

zsh$Friday, April 22, 2011

class Person def name @name end if Superpowers.enabled? def give_superpowers @ability = "Fly" end endend

class Model def self.acts_as_tree define_method :parent do find(parent_id) end define_method :children do where(:parent_id => self.id) end endend

class Category < Model acts_as_treeend

@category.parent@category.children

Module Mix-ins

module Jazz class Chord end class Scale endend

Jazz::Chord.newJazz::Scale.new

module FilePersistence def load_from(path) endend

class MusicCollection include Enumerable include FilePersistenceend

@collection = FileCollection.new@collection.load_from "songs"@collection.each do |song| song.playend

Isn’t too much freedom a bad thing?

In Theory? Yes.

In Practice? It’s not as bad as you

would think...

Greater Good vs. Greater Evil

Solution Space (Good)

Greater Good vs. Greater Evil

Solution Space (Good)

Pitfalls (Evil)

Overlapping Safety

Safety/Confidence from Static

Typing

Overlapping Safety

Safety from Static Typing

Safety/Confidence from Test Suite

Domain-Specific Languages

• Sub-Languages of Ruby for particular purposes

• High-Level Abstractions

• Captures Knowledge in an Extremely Readable Way

Markaby::Builder.new.html do head { title "Boats.com" } body do h1 "Boats.com has great deals" ul.specials do li "$49 for a canoe" li "$39 for a raft" li "$29 for a huge boat" end endend

<html> <head><title>Boats.com</title></head> <body> <h1>Boats.com has great deals</h1> <ul class="specials"> <li>$49 for a canoe</li> <li>$39 for a raft</li> <li>$29 for a huge boat</li> </ul> </body></html>

class Payment state_machine :state, :initial => :new do event :authorize do transition :new => :authorized end event :capture do transition :authorized => :captured end before_transition any => :authorize, :do => :authorize_card before_transition any => :capture, :do => :capture_card endend

@payment = Payment.new@payment.state # => "new"@payment.authorize!@payment.capture!

@payment.captured? # => trueFriday, April 22, 2011

class Comment < ActiveRecord::Base belongs_to :article validates :name, :email, :comment, :presence => true def approve! update_attribute :approved, true endend

class Article < ActiveRecord::Base has_many :comments scope :published, where(published: true) validates :title, :presence => true validates :content, :length => { minimum: 50 }end

class User < ActiveRecord::Base has_attached_file :avatar, styles: { medium: "300x300>", thumb: "100x100>" }end

@user.avatar.url(:medium)

<% form_for(@user) do |f| %> <%= f.file_field :avatar %><% end %>

Chord['Ebmaj7'].notesChord['maj7'].in_key_of('Eb').notes# => ['Eb', 'G', 'Bb', 'D']

Scale['Whole Tone'].notes# => ['C', 'D', 'E', 'F#', 'G#', 'Bb']

Scale['Major'].in_key_of('Eb').modes['Dorian'].notes# => ['F', 'G', 'Ab', 'Bb', 'C', 'D', 'Eb']

Scale['Major']['Dorian'].chords.symbols# => ['min7', 'min6']

Chord['Amin7'].modes.names# => ['A Dorian']

every 3.hours do command "/usr/bin/my_great_command"end

every 1.day, :at => ['4:30 am', '10:30 am'] do runner "MyModel.task_to_run"end

every :hour do runner "SomeModel.ladeeda"end

every :sunday, :at => '12pm' do runner "Task.do_something_great"end

Person.joins { articles.comments }.where {{ articles.comments => ( id.in([1,2,3]) | body.matches('First post!%') )}}.to_sql

=> SELECT "people".* FROM "people" INNER JOIN "articles" ON "articles"."person_id" = "people"."id" INNER JOIN "comments" ON "comments"."article_id" = "articles"."id" WHERE (("comments"."id" IN (1, 2, 3) OR "comments"."body" LIKE 'First post!%'))

C mmunity

Cohesive & ActiveCommon Style/IdiomFocuses on Quality

Passionate About ToolsTesting Your Software

Test Your Damn Software

describe User do before do @user = User.create(:login => "joe", :password => "pw") end it "should be invalid without username" do @user.username = "" @user.should_not be_valid @user.should have(1).error_on(:username) end it "should destroy" do expect { @user.destroy }.to change { User.count }.by(-1) endend

describe Key do it "should default to C" do Key.default.name.should == "C" end it "should expose 12 primary keys" do Key.should have(12).primaries end it "should treat Eb and D# as enharmonic" do Key['Eb'].should be_enharmonic_with(Key['D#']) endend

It’s a great time to learn Ruby

• Rails 3 recently released - very solid!

• Ruby 1.9 - Runs on a proper VM and very fast

• Bundler / RVM for Ruby and Gem dependencies

• Other Rubies maturing: JRuby, MacRuby, Rubinius

• Deployment easy with mod_rails or Heroku

• Strong community with resources/help

“Ruby fits my brain like a glove”

- David Heinemeier Hansson

“Power with clarity and choice”

- Glenn Vanderburg

Resources

• http://tryruby.org

• http://rubykoans.com

• http://sdruby.org

Ben Hughes@rubiety

http://benhugh.es

the ruby idiom

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