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Intro to Ruby

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Chippew Valley Code Camp 2009 talk. Very similar to the slides from Twin Cities Code Camp 7.

Chippew Valley Code Camp 2009 talk. Very similar to the slides from Twin Cities Code Camp 7.

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  • Hi everyone. I’m Brian. I do Ruby and Rails training and consulting.
  • Maybe you do... but it can be even more fun.
  • I hated programming. I did some when I was a kid, but it wasn’t what I wanted to do. I liked the web. And I started building sites in 1995 for small businesses.
  • so I started learning to program in ASP and eventually PHP. Even did some Java and some Oracle DBA stuff in there.
  • I was getting burned out, spending hours fighting with the languages while writing the same kind of applications over again.
  • A consultant who was working with me on a Java project introduced me to Rails
    and now, four years later,
  • I get to work on fun projects, work with amazing people, I’m excited about what I do, and I even got to write some books.
  • I want to get you excited about this language. I want to you to ask me any questions you have, and I want you to run home and start coding! So the best way to do that is to show you what you can do.
  • We can make a desktop application that works on Windows, Mac, and Linux using Shoes.
  • We can make a very simple iPhone-enabled website with Sinatra. This one serves files to you in around 50 lines of code.
  • We can use Sass to generate stylesheets for our applications. We can use variables for our colors and widths!
  • Use Rails. Rails is a great framework for building web applications. And despite what you’ve heard, it scales exceptionally well, as long as you know how to scale a web application and you’ve written good code.
  • Use Rails to kickstart a CMS.
  • Highly dynamic, high level, 100% object oriented, 100% open source, and really easy to learn.
  • Ruby was created by Yukihiro Matsumoto (Matz) in 1993. It’s built on C, and has many implementations, including JRuby, which runs on the JVM, and IronRuby, which runs on the .Net platform.
  • “How you feel is more important than what you do. “
    The entire language is designed for programmer productivity and fun.
  • Principle of Least Surprise - This means The language should behave in a way that is not confusing to experienced developers. It doesn’t mean that it works like your current favorite language! But as you get used to Ruby, you’ll find that you ramp up quickly.
  • Ruby achieves this through a consistant API. You won’t find yourself guessing too much what methods are available to you.
  • It also helps that the syntax is simple. There are no unnecessary semicolons or curly braces. The interpreter knows when lines end.
  • We have numbers, strings, multiplication, addition, subtraction, and division, just like everyone else.
  • The square brackets denote an array.
  • This is the hash symbol, or the hash rocket. Whenever you see this, you’re dealing with a hash.
  • When you see these, you’re looking at Symbols. They represent names and some strings. They conserve memory, as repeating a symbol in your code uses the same memory reference, whereas repeating a string creates a new object on each use.
  • Unless is an alias for “if not”. Subtle, but sometimes much more readable.
  • You can append these suffixes to statements to prevent them from firing. This is a great space saver and it’s easy to read
  • The two arrows (>>) is actually a method on the Date object that adds months. So here, we’re adding six months to the start date and comparing it to today

    Notice here that the input parameter is assumed to be a date. There’s no type checking here.
  • The = is part of the method name. And Ruby’s interpreter doesn’t mind you putting a space in front of it to make it easier to read!
  • Making getters and setters is so common that Ruby can do it for you.
  • It assumes you are an intelligent person who wants to get things done. It will not try to protect you from your own stupidity.
  • In fact,
  • Test All The Effing Time! Let’s go through adding our “on_probation?” method to our Person class. A person is on probation for the first six months of employment.
  • Here we have two tests, one using a person hired today, and another using a person last year.
  • Did we miss any cases?
  • Everything is an object in Ruby. There are no primitive types. Strings, integers, floats, everything. Even Nil, True, and False!
  • Everything. Even 0 and -1.
  • I’m not here to tell you that dynamically typed languages are better than statically typed languages. I prefer dynamic typing. I am more productive with it. And most of the claims against it are false.
  • We don’t need to specify a “return” keyword.
  • In this example, if the status is not closed, this method will return false. In Rails, if a before_save method returns false, the record won’t save to the database.
  • There are methods on arrays and hashes to iterate over the elements stored within.
  • Blocks let you pass code as a parameter, so that the code may be run within the method. If you’ve used closures or anonymous functions, you already understand this. But this is how Ruby developers work every day.
  • We can create modules of code that we can mix in to our classes.
  • In this example, we’re using modules to replace inheritence. However, since classes are objects, we can also apply modules to instances of objects at runtime.
  • If it walks like a duck, and talks like a duck, it’s a duck. Even if it’s not.
  • Declare modules that encapsulate behavior. Here we have a doctor, a ninja, and a musician.
  • We can then mix in the behaviors to the instance of the class. Its type doesn’t really matter. We can ask the instance if it has the methods we want and we can call them.
  • Reflection is built into the core language. It’s not a tacked on library, and it’s meant to be used to improve your code.
  • We can ask our model all sorts of questions, and even actually send messages dynamically.
  • We can loop over an array and generate methods on the object.
  • Sinatra is a simple web framework that basically maps incoming requests to backend code that produces responses.
  • That little bit of code gets us a working web application that handles requests.
  • We write stories using plain text, that describes what we want to do.

Transcript

  • 1. intro to ruby brian hogan New Auburn Personal Computer Services LLC twitter: bphogan email: brianhogan at napcs.com
  • 2. programming is fun. twitter: bphogan email: brianhogan at napcs.com
  • 3. you just don’t know it yet. twitter: bphogan email: brianhogan at napcs.com
  • 4. I was a designer. I hated programming. twitter: bphogan email: brianhogan at napcs.com
  • 5. my clients wanted interactive websites... twitter: bphogan email: brianhogan at napcs.com
  • 6. and I started to hate my life. twitter: bphogan email: brianhogan at napcs.com
  • 7. I learned Ruby in 2005 and fell in love... twitter: bphogan email: brianhogan at napcs.com
  • 8. twitter: bphogan email: brianhogan at napcs.com
  • 9. So what can kinds of things can you do with Ruby? twitter: bphogan email: brianhogan at napcs.com
  • 10. 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
  • 11. 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
  • 12. !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
  • 13. got a great idea and want to get it out there quickly? twitter: bphogan email: brianhogan at napcs.com
  • 14. twitter: bphogan email: brianhogan at napcs.com
  • 15. got a big site that’s hard to maintain? twitter: bphogan email: brianhogan at napcs.com
  • 16. twitter: bphogan email: brianhogan at napcs.com
  • 17. So, what is Ruby? • Highly dynamic • Very high level • 100% object oriented • 100% open-source • Really easy to learn
  • 18. History Smalltalk C++ Ruby Java VB 6 C# (1983) (1989) (1993) (1995) (1996) (2000) twitter: bphogan email: brianhogan at napcs.com
  • 19. twitter: bphogan email: brianhogan at napcs.com
  • 20. Ruby follows the Principle of Least Surprise. twitter: bphogan email: brianhogan at napcs.com
  • 21. consistent API "Brian".length ["red", "green", "blue"].length [:first_name => "Brian", :last_name => "Hogan"].length User.find_all_by_last_name("Hogan").length
  • 22. and a simple syntax age = 42 first_name = "Homer" start_date = Date.new 1980, 06, 05 annual_salary = 100000.00
  • 23. Basic Ruby twitter: bphogan email: brianhogan at napcs.com
  • 24. Standard operators 5 + 5 10 * 10 "Hello" + "World" 25 / 5
  • 25. Arrays colors = ["Red", "Green", "Blue"]
  • 26. Hashes (Dictionaries) attributes = {:age => 25, :first_name => "Homer", :last_name => "Simpson"}
  • 27. =>
  • 28. :foo twitter: bphogan email: brianhogan at napcs.com
  • 29. Simple control logic if on_probation(start_date) puts "Yes" else puts "no" end
  • 30. Unless if !current_user.admin? redirect_to "/login" end unless current_user.admin? redirect_to "/login" end
  • 31. Conditionals as statement suffixes redirect_to "/login" unless current_user.admin?
  • 32. Methods (functions) are simple too. # if start date + 6 months is > today def on_probation?(start_date) (start_date >> 6) > Date.today end
  • 33. 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
  • 34. 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
  • 35. 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
  • 36. Ruby is a loaded gun. twitter: bphogan email: brianhogan at napcs.com
  • 37. So, write good tests. twitter: bphogan email: brianhogan at napcs.com
  • 38. TATFT twitter: bphogan email: brianhogan at napcs.com
  • 39. 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
  • 40. Implement the method class Person attr_accessor :name, :start_date def on_probation? (start_date >> 6) > Date.today end end
  • 41. And the tests pass. twitter: bphogan email: brianhogan at napcs.com
  • 42. Testing first helps you think about your design AND your features. twitter: bphogan email: brianhogan at napcs.com
  • 43. Every professional Ruby developer writes tests first for production code. twitter: bphogan email: brianhogan at napcs.com
  • 44. Ten Simple Rules For Programming in My Favorite Language.
  • 45. 1. Everything is an object twitter: bphogan email: brianhogan at napcs.com
  • 46. 25.class Fixnum "brian".class String [1,2,3].class Array
  • 47. 2. Everything evaluates to true except nil or false twitter: bphogan email: brianhogan at napcs.com
  • 48. 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
  • 49. 3. Variables are dynamically typed but DATA is strongly typed! twitter: bphogan email: brianhogan at napcs.com
  • 50. age = 32 name = "Brian" TypeError: can't convert Fixnum into String name + age age = 32 name = "Brian" “Brian32” name + age.to_s
  • 51. 4. Every method returns the last evaluation implicitly twitter: bphogan email: brianhogan at napcs.com
  • 52. def limit_reached? self.projects.length > 0 end def welcome_message if current_user.anonymous? "You need to log in." else "Welcome!" end end
  • 53. 5. Every expression evaluates to an object twitter: bphogan email: brianhogan at napcs.com
  • 54. result = if current_user.anonymous? "You need to log in." else "Welcome!" end
  • 55. It is very easy to accidentally return false! def before_save if self.status == "closed" self.closed_on = Date.today end end
  • 56. 6. Classes are objects twitter: bphogan email: brianhogan at napcs.com
  • 57. WRONG! person = new Person RIGHT! person = Person.new
  • 58. 7. You need to use and understand blocks. twitter: bphogan email: brianhogan at napcs.com
  • 59. Blocks can iterate roles.each do |role| puts "<li>" + role.name + "<li>" end
  • 60. They can also encapsulate code. ActiveRecord::Schema.define do create_table :pages do |t| t.string :name t.text :body t.timestamps end end
  • 61. Every method can take a block! 5.times do puts "Hello!" end
  • 62. 8. Favor modules over inheritance twitter: bphogan email: brianhogan at napcs.com
  • 63. 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
  • 64. Do not use type, use behaviors. twitter: bphogan email: brianhogan at napcs.com
  • 65. twitter: bphogan email: brianhogan at napcs.com
  • 66. 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
  • 67. 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!"
  • 68. 9. Embrace Reflection twitter: bphogan email: brianhogan at napcs.com
  • 69. person.respond_to?(:name) true person.respond_to?(:age) false person.send(:name) “Brian”
  • 70. 10. Write code that writes code. twitter: bphogan email: brianhogan at napcs.com
  • 71. 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?
  • 72. haml and sass twitter: bphogan email: brianhogan at napcs.com
  • 73. 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
  • 74. 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>
  • 75. 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
  • 76. CSS #header { color: #333333; border-left: 1px; border-right: 2px; color: red; } #header a { font-weight: bold; text-decoration: none; }
  • 77. StaticMatic demo twitter: bphogan email: brianhogan at napcs.com
  • 78. sinatra twitter: bphogan email: brianhogan at napcs.com
  • 79. Hello Sinatra! require 'rubygems' require 'sinatra' get "/" do "Hello Sinatra!" end
  • 80. Sinatra demo twitter: bphogan email: brianhogan at napcs.com
  • 81. cucumber twitter: bphogan email: brianhogan at napcs.com
  • 82. 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
  • 83. Testing the Wiki with Webrat and Cucumber twitter: bphogan email: brianhogan at napcs.com
  • 84. Ruby will make you productive. twitter: bphogan email: brianhogan at napcs.com
  • 85. And happy. twitter: bphogan email: brianhogan at napcs.com
  • 86. 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
  • 87. Questions? Twitter: bphogan brianhogan at napcs.com twitter: bphogan email: brianhogan at napcs.com