Intro to Ruby - Twin Cities Code Camp 7

intro to ruby brian hogan New Auburn Personal Computer Services LLC

programming is fun.

you just don’t know it yet.

I was a designer. I hated programming.

my clients wanted interactive websites...

and I started to hate my life.

I learned Ruby in 2005 and fell in love...

So what can kinds of things can you do with Ruby?

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

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>

!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

got a great idea and want to get it out there quickly?

got a big site that’s hard to maintain?

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)

Ruby follows the Principle of Least Surprise.

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

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"}

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.

So, write good tests.

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.

Testing ﬁrst helps you think about your design AND your features.

Every professional Ruby developer writes tests ﬁrst for production code.

Ten Simple Rules For Programming in My Favorite Language.

1. Everything is an object

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

2. Everything evaluates to true except nil or false

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!

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

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

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

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

7. You need to use and understand blocks.

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

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.

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

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

10. Write code that writes code.

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

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

sinatra

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

Sinatra demo

cucumber

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!"

Testing the Wiki with Webrat and Cucumber

Ruby will make you productive.

And happy.

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/

Questions? Twitter: bphogan bphogan at gmail

http://www.napcsweb.com	38
http://www.slideshare.net	3
http://coderwall.com	3

Intro to Ruby - Twin Cities Code Camp 7

by Brian Hogan on Oct 25, 2009

Accessibility

Categories

Tags

Upload Details

Usage Rights

3 Embeds 44

Statistics

Intro to Ruby - Twin Cities Code Camp 7 — Presentation Transcript