Intro to Ruby

intro to ruby brian hogan New Auburn Personal Computer Services LLC twitter: bphogan email: brianhogan at napcs.com

programming is fun. twitter: bphogan email: brianhogan at napcs.com

you just don’t know it yet. twitter: bphogan email: brianhogan at napcs.com

I was a designer. I hated programming. twitter: bphogan email: brianhogan at napcs.com

my clients wanted interactive websites... twitter: bphogan email: brianhogan at napcs.com

and I started to hate my life. twitter: bphogan email: brianhogan at napcs.com

I learned Ruby in 2005 and fell in love... twitter: bphogan email: brianhogan at napcs.com

twitter: bphogan email: brianhogan at napcs.com

So what can kinds of things can you do with Ruby? twitter: bphogan email: brianhogan at napcs.com

Shoes.app do para "Item name" @name = edit_line button "Add to list" do @names.append do para @name.text end @name.text = "" end button("Clear the list") {@names.clear} @names = stack :width=>"100%", :height=>"90%" end twitter: bphogan email: brianhogan at napcs.com

require 'sinatra' require 'pathname' get "/" do dir = "./files/" @links = Dir[dir+"*"].map { |file| file_link(file) }.join erb :index end helpers do def file_link(file) filename = Pathname.new(file).basename "<li><a href='#{file}' target='_self'>#{filename}</a></li>" end end use_in_file_templates! __END__ @@ index <html> <head> <meta name="viewport" content="width=320; initial-scale=1.0; maximum-scale=1.0; user-scalable=0;"/> <style type="text/css" media="screen">@import "/stylesheets/iui.css";</style> <script type="application/x-javascript" src="/javascripts/iui.js"></script> </head> <body> <div class="toolbar"> <h1 id="pageTitle"></h1> </div> <ul id="home" title="Your files, sir." selected="true"> <%= @links %> </ul> </body> </html> twitter: bphogan email: brianhogan at napcs.com

!the_border = 1px !base_color = #111 #header { #header color: #333333; color = !base_color * 3 border-left: 1px; border-left= !the_border border-right: 2px; border-right = !the_border * 2 color: red; } color: red #header a { font-weight: bold; a text-decoration: none; } font-weight: bold text-decoration: none twitter: bphogan email: brianhogan at napcs.com

got a great idea and want to get it out there quickly? twitter: bphogan email: brianhogan at napcs.com

got a big site that’s hard to maintain? twitter: bphogan email: brianhogan at napcs.com

So, what is Ruby? • Highly dynamic • Very high level • 100% object oriented • 100% open-source • Really easy to learn

History Smalltalk C++ Ruby Java VB 6 C# (1983) (1989) (1993) (1995) (1996) (2000) twitter: bphogan email: brianhogan at napcs.com

Ruby follows the Principle of Least Surprise. twitter: bphogan email: brianhogan at napcs.com

consistent API "Brian".length ["red", "green", "blue"].length [:first_name => "Brian", :last_name => "Hogan"].length User.find_all_by_last_name("Hogan").length

and a simple syntax age = 42 first_name = "Homer" start_date = Date.new 1980, 06, 05 annual_salary = 100000.00

Basic Ruby twitter: bphogan email: brianhogan at napcs.com

Standard operators 5 + 5 10 * 10 "Hello" + "World" 25 / 5

Arrays colors = ["Red", "Green", "Blue"]

Hashes (Dictionaries) attributes = {:age => 25, :first_name => "Homer", :last_name => "Simpson"}

:foo twitter: bphogan email: brianhogan at napcs.com

Simple control logic if on_probation(start_date) puts "Yes" else puts "no" end

Unless if !current_user.admin? redirect_to "/login" end unless current_user.admin? redirect_to "/login" end

Conditionals as statement sufﬁxes redirect_to "/login" unless current_user.admin?

Methods (functions) are simple too. # if start date + 6 months is > today def on_probation?(start_date) (start_date >> 6) > Date.today end

Classes are easy too. class Person @started_on = Date.today @name = "" def started_on=(date) @started_on = date end def started_on @started_on end end

Class instance variables are private class Person @started_on = Date.today Expose them through @name = "" accessor methods that def started_on=(date) @started_on = date resemble C# and VB end Property members. def started_on @started_on end person = Person.new person.age = 32 def name=(name) person.name = "Brian" @name = name end person.age => 32 def name person.name @name => "Brian" end end

Let Ruby write code for you! class Person @started_on = Date.today @name = "" def started_on=(date) class Person @started_on = date end attr_accessor :name attr_accessor :started_on def started_on @started_on end end def name=(name) @name = name end def name @name end end

Ruby is a loaded gun. twitter: bphogan email: brianhogan at napcs.com

So, write good tests. twitter: bphogan email: brianhogan at napcs.com

TATFT twitter: bphogan email: brianhogan at napcs.com

def test_user_hired_today_should_be_on_probation person = Person.new person.hired_on = Date.today assert person.on_probation? end test_user_hired_last_year_should_not_be_on_probation person = Person.new person.hired_on = 1.year.ago assert !person.on_probation? end

Implement the method class Person attr_accessor :name, :start_date def on_probation? (start_date >> 6) > Date.today end end

And the tests pass. twitter: bphogan email: brianhogan at napcs.com

Testing ﬁrst helps you think about your design AND your features. twitter: bphogan email: brianhogan at napcs.com

Every professional Ruby developer writes tests ﬁrst for production code. twitter: bphogan email: brianhogan at napcs.com

Ten Simple Rules For Programming in My Favorite Language.

1. Everything is an object twitter: bphogan email: brianhogan at napcs.com

25.class Fixnum "brian".class String [1,2,3].class Array

2. Everything evaluates to true except nil or false twitter: bphogan email: brianhogan at napcs.com

x = 0 0 puts x if x x = -1 -1 puts x if x x = false nil puts x if x x = nil nil puts x if x

3. Variables are dynamically typed but DATA is strongly typed! twitter: bphogan email: brianhogan at napcs.com

age = 32 name = "Brian" TypeError: can't convert Fixnum into String name + age age = 32 name = "Brian" “Brian32” name + age.to_s

4. Every method returns the last evaluation implicitly twitter: bphogan email: brianhogan at napcs.com

def limit_reached? self.projects.length > 0 end def welcome_message if current_user.anonymous? "You need to log in." else "Welcome!" end end

5. Every expression evaluates to an object twitter: bphogan email: brianhogan at napcs.com

result = if current_user.anonymous? "You need to log in." else "Welcome!" end

It is very easy to accidentally return false! def before_save if self.status == "closed" self.closed_on = Date.today end end

6. Classes are objects twitter: bphogan email: brianhogan at napcs.com

WRONG! person = new Person RIGHT! person = Person.new

7. You need to use and understand blocks. twitter: bphogan email: brianhogan at napcs.com

Blocks can iterate roles.each do |role| puts "<li>" + role.name + "<li>" end

They can also encapsulate code. ActiveRecord::Schema.define do create_table :pages do |t| t.string :name t.text :body t.timestamps end end

Every method can take a block! 5.times do puts "Hello!" end

8. Favor modules over inheritance twitter: bphogan email: brianhogan at napcs.com

module SharedValidations def self.included(base) base.validates_presence_of :name base.validates_uniqueness_of :name end end class Project class Task include SharedValidations include SharedValidations end end

Do not use type, use behaviors. twitter: bphogan email: brianhogan at napcs.com

module Doctor module Ninja def treat_patient def attack puts "All better!" puts "You’re dead!" end end end end module Musician def play_guitar puts "meedily-meedily-meedily-meeeeeeeeee!" end end

person = Person.new person.extend Ninja "You're dead!" person.attack person.extend Doctor "All better!" person.treat_patient person.extend Musician "meedily-meedily- person.play_guitar meedily-meeeeeeeeee!"

9. Embrace Reﬂection twitter: bphogan email: brianhogan at napcs.com

person.respond_to?(:name) true person.respond_to?(:age) false person.send(:name) “Brian”

10. Write code that writes code. twitter: bphogan email: brianhogan at napcs.com

class User ROLES = ["admin", "superadmin", "user", "moderator"] ROLES.each do |role| class_eval <<-EOF def #{role}? self.roles.include?("#{role}") end EOF end end user = User.new user.admin? user.moderator?

haml and sass twitter: bphogan email: brianhogan at napcs.com

HAML !!! #wrapper.container_12 #header.grid_12 %h1 The awesome site %ul#navbar.grid_12 %li %a{:href => "index.html"} Home %li %a{:href => "products"} Products %li %a{:href => "services"} Services #middle.grid_12 %h2 Welcome #footer.grid_12 %p Copyright 2009 SomeCompany

HTML <div class='container_12' id='wrapper'> <div class='grid_12' id='header'> <h1>The awesome site</h1> </div> <ul class='grid_12' id='navbar'> <li> <a href='index.html'>Home</a> </li> <li> <a href='products'>Products</a> </li> <li> <a href='services'>Services</a> </li> </ul> <div class='grid_12' id='middle'> <h2>Welcome</h2> </div> <div class='grid_12' id='footer'> <p>Copyright 2009 SomeCompany</p> </div> </div>

SASS !the_border = 1px !base_color = #111 #header color = !base_color * 3 border-left= !the_border border-right = !the_border * 2 color: red a font-weight: bold text-decoration: none

CSS #header { color: #333333; border-left: 1px; border-right: 2px; color: red; } #header a { font-weight: bold; text-decoration: none; }

StaticMatic demo twitter: bphogan email: brianhogan at napcs.com

sinatra twitter: bphogan email: brianhogan at napcs.com

Hello Sinatra! require 'rubygems' require 'sinatra' get "/" do "Hello Sinatra!" end

Sinatra demo twitter: bphogan email: brianhogan at napcs.com

cucumber twitter: bphogan email: brianhogan at napcs.com

Feature: creating a new page in the wiki As an average anonymous user I want to create a page about Ruby So that I can tell everyone how awesome it is. Scenario: Creating a new page and editing its content Given I go to "/ruby" Then I should see "Edit this page" When I click "Edit this page" And I fill in "body" with "Ruby is the best programming language in the whole world!" And I press "Save" Then I should see "Ruby is the best programming language in the whole world!" twitter: bphogan email: brianhogan at napcs.com

Testing the Wiki with Webrat and Cucumber twitter: bphogan email: brianhogan at napcs.com

Ruby will make you productive. twitter: bphogan email: brianhogan at napcs.com

And happy. twitter: bphogan email: brianhogan at napcs.com

Resources: Try Ruby in your browser! http://tryruby.sophrinix.com/ Try SASS online: http://sass-lang.com/try.html Try HAML online: http://haml-lang.com/try.html http://staticmatic.rubyforge.org/ Sinatra: http://www.sinatrarb.com/ Sinatra Wiki source: http://github.com/napcs/sinatriki Cucumber: http://cukes.info/ WATIR: http://watir.com/ twitter: bphogan email: brianhogan at napcs.com

Questions? Twitter: bphogan brianhogan at napcs.com twitter: bphogan email: brianhogan at napcs.com

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Intro to Ruby

by Brian Hogan

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