Ruby 101

An introduction to the Ruby programming language, presented at Rails Girls Dallas 2012.

Transcript

1. 101 Rails Girls Dallas — Cameron Desautels
2. About Me (Ruby) Software Developer at OrgSync @camdez  
3. What is Ruby? •A programming language — a precise way of telling the computer what we want it to do. •Optimized for developer happiness.
4. What is Ruby? 3.times { print “I love Ruby! ” }
5. What is Ruby? 3.times { print “I love Ruby! ” } I love Ruby! I love Ruby! I love Ruby!
6. What can we do with Ruby? 
7. Make a Desktop Application Bowline, a framework for making cross platform desktop applications in Ruby, HTML and JavaScript.
8. Make an iPhone App +
9. Revolutionize Fashion Amisha Gadani’s Porcupine Dress: “hand-painted quills prick up when the wearer detects a threat” http://amishagadani.com/Work/porcupine/index.html
10. Build a Robot http:// playground.arduino.cc/ Interfacing/Ruby Photo courtesy of Randomskk on Flickr.
11. Make a Webapp
12. Make a Webapp
13. Ruby & Rails •Ruby on Rails is a framework for writing web applications in Ruby. •Rails is written in Ruby and so are our Rails applications.
14. Ruby & Rails •Ruby is the foundation.
15. http://tryruby.org Enough talk, let’s code.
16. Let’s learn the basics. 
17. Objects •Things in Ruby are objects. •These things come in types called classes. •e.g. Strings, Integers, Arrays, ActiveRecord::Models, etc.
18. Methods •Methods are verbs—actions and operations on objects (things). "Rails Girls".reverse => "slriG sliaR" 3.even? => false
19. Methods •Sometimes methods take parameters (a.k.a arguments). •Parameters are (optionally) surrounded by parentheses. "I like broccoli".sub("broccoli", "candy") => "I like candy"
20. Kernel Methods •A small set of basic methods available everywhere. gets # read a string from the terminal puts "somethings" # put (print) a string to terminal exit # exit the program
21. Methods •It’s fun and easy to define our own: class String def praise self + " is wonderful" end end "chunky bacon".praise => "chunky bacon is wonderful"
22. Evaluation "slrig sliar".reverse.sub("rails", "ruby").capitalize
23. Evaluation "rails girls".sub("rails", "ruby").capitalize
24. Evaluation "ruby girls".capitalize
25. Evaluation "Ruby girls"
26. Evaluation "slrig sliar".reverse.sub("rails", "ruby").capitalize "rails girls".sub("rails", "ruby").capitalize "ruby girls".capitalize => "Ruby girls"
27. Variables •Names we give to things. •Places to store things we’ll want later. name = "Cameron" => "Cameron" greeting = "Hello, " + name => "Hello, Cameron" SPEED_OF_LIGHT = 299792458 # m/s
28. Strings •Bits of text (words, sentences, paragraphs, etc.). "rail".length => 4 "rail".reverse => "liar" "rail".capitalize => "Rail" "rail" + "s girls" => "rails girls" "rails girls".split(" ") => ["rails", "girls"]
29. Arrays •Lists of things. orgsync_devs = ["Cameron", "Kevin", "Clifton", "Aaron", "Cody", "Sonny", "Taylor", "Justin"] => ["Cameron", "Kevin", "Clifton", "Aaron", "Cody", "Sonny", "Taylor", "Justin"] orgsync_devs.count => 8 orgsync_devs.sort.join(", ") => => "Aaron, Cameron, Clifton, Cody, Justin, Kevin, Sonny, Taylor" orgsync_devs[2] => "Clifton"
30. Hashes •Key / value associations. book = { "title" => "Harry Potter and the Sorcerer's Stone", "author" => "J.K. Rowling", "page_count" => 320} book["author"] => "J.K. Rowling" book["isbn"] = "0439708184" => "0439708184" book => {"title"=>"Harry Potter and the Sorcerer's Stone", "author"=>"J.K. Rowling", "page_count"=>320, "isbn"=>"0439708184"}
31. Conditionals •Do something if certain conditions are true. •Possibly something else otherwise. def analyze_book(book) if book["page_count"].even? puts "This book has an even number of pages." else puts "This book has an odd number of pages." end end
32. Truthiness •Everything in Ruby has a “truth value”. •Things that are considered false: false, nil •Things that are considered true: everything else. (1, -10,“Hello”, [], true) if true puts "This code will always run." else puts "This book will never run." end
33. Truthiness 2.even? => true 3.even? => false 3 > 2 => true puts "Will this get printed?" if "something"
34. Loops •Do something repeatedly. 3.times { print “I love Ruby! ” } => I love Ruby! I love Ruby! I love Ruby!
35. Loops •Do something repeatedly. 3.times do print “I love Ruby! ” end I love Ruby! I love Ruby! I love Ruby!
36. Loops •Do something repeatedly—for each item in an array. ["snozberries", "raspberries", "schnitzel"].each do |food| print "Let's eat " + food + "! " end Let's eat snozberries! Let's eat raspberries! Let's eat schnitzel!
37. Identification Exercise def greet(person) greeting = "Hello, " + person puts greeting end ["Shufen", "Inez", "Kevin"].each do |name| if name.length > 4 greet name end end # Hello, Shufen # Hello, Kevin
38. Ruby & Its Environment
39. irb / rails console •Interactive evaluation of Ruby code in our terminal. •Great for testing things out.
40. Running Ruby Programs •ruby yourfile.rb
41. The Ruby Community •Open source — unrestricted access to other people’s code •GitHub(.com) — a central location where Rubyists (and others) share code •Gems — prepackaged, reusable bits of Ruby functionality
42. GET EXCITED AND MAKE THINGS!