Old presentation updated for Geek Camp Baguio May 2012

1. Ruby and Rails
by example

3. Ruby is simple in appearance,
but is very complex inside,
just like our human body.
- Yukihiro "matz" Matsumoto,
creator of Ruby

4. Example 0:
Hash / Dictionary

5. // Using C#
using System;
using System.Collections;
...
Hashtable openWith = new Hashtable();
openWith.Add("txt", "notepad.exe");
openWith.Add("bmp", "paint.exe");
openWith.Add("dib", "paint.exe");
openWith.Add("rtf", "wordpad.exe");

6. # Using Ruby
openWith = { "txt" => "notepad.exe",
"bmp" => "paint.exe",
"dib" => "paint.exe",
"rtf" => "wordpad.exe" }

7. # Using Ruby 1.9
openWith = { txt: "notepad.exe",
bmp: "paint.exe", dib: "paint.exe",
rtf: "wordpad.exe" }

9. DO MORE
with
LESS CODE

10. // Using C#
using System;
using System.Collections;
...
Hashtable openWith = new Hashtable();
openWith.Add("txt", "notepad.exe");
openWith.Add("bmp", "paint.exe");
openWith.Add("dib", "paint.exe");
openWith.Add("rtf", "wordpad.exe");

11. Example 1:
Hello World

12. puts "Hello World!"

13. Example 2:
Create a Binary Tree

14. class Node
attr_accessor :value
def initialize(value = nil)
@value = value
end
attr_reader :left, :right
def left=(node); @left = create_node(node); end
def right=(node); @right = create_node(node); end
private
def create_node(node)
node.instance_of? Node ? node : Node.new(node)
end
end

15. Example 2.1:
Traverse the
Binary Tree

16. def traverse(node)
visited_list = []
inorder(node, visited)
puts visited.join(",")
end
def inorder(node, visited)
inorder(node.left, visited) unless node.left.nil?
visited << node.value
inorder(node.right, visited) unless node.right.nil?
end

17. def traverse(node)
visited_list = []
inorder node, visited
puts visited.join ","
end
def inorder(node, visited)
inorder node.left, visited unless node.left.nil?
visited << node.value
inorder node.right, visited unless node.right.nil?
end

18. Example 3:
Create a Person →
Student →
College Student
class hierarchy

19. class Person
attr_accessor :name
end
class Student < Person
attr_accessor :school
end
class CollegeStudent < Student
attr_accessor :course
end
x = CollegeStudent.new
x.name = "John Doe"
x.school = "ABC University"
x.course = "Computer Science"

20. Example 4:
Call a method in a
"primitive"

21. nil.methods
true.object_id
1.upto(10) do |x|
puts x
end

22. Example 5:
Find the sum of the
squares of all numbers
under 10,000 divisible
by 3 and/or 5

23. x = 1
sum = 0
while x < 10000 do
if x % 3 == 0 or x % 5 == 0
sum += x * x
end
end
puts sum

24. puts (1..10000).
select { |x| x % 3 == 0 or x % 5 == 0}.
map {|x| x * x }.
reduce(:+)

25. Example 6:
Find all employees
older than 30 and sort
by last name

26. oldies = employees.select { |e| e.age > 30 }.
sort { |e1, e2| e1.last_name <=> e2.last_name }

27. Example 7:
Assign a method to a
variable

28. hello = Proc.new { |string| puts "Hello #{string}" }
hello.call "Alice"

29. Example 8:
Add a "plus" method to
all numbers

30. class Numeric
def plus(value)
self.+(value)
end
end

31. Example 9:
Define different
behavior for different
instances

32. alice = Person.new
bob = Person.new
alice.instance_eval do
def hello
puts "Hello"
end
end
def bob.hello
puts "Howdy!"
end

33. Example 10:
Make Duck and
Person swim

34. module Swimmer
def swim
puts "This #{self.class} is swimming"
end
end
class Duck
include Swimmer
end
class Person
include Swimmer
end
Duck.new.swim
Student.new.swim

37. Example 0:
Make a Twitter Clone

38. $ rails new twitclone
$ cd twitclone
$ rails generate scaffold tweet message:string
$ rake db:migrate
$ rails server

39. $ rails new twitclone
$ cd twitclone
$ rails generate scaffold tweet message:string
$ rake db:migrate
$ rails server

40. Ruby on Rails
ISN'T MAGIC

42. Ruby Features

43. Dynamic
Object Oriented
Functional
Metaprogramming

44. +

45. Software
Engineering
"Best Practices"

46. MVC CoC
DRY
TDD REST

47. = Productivity

48. = Magic?

49. DO MORE
with
LESS CODE

50. Rails Example:
Demo a Twitter Clone

51. https://github.com/bryanbibat/microblog31
Authentication – Devise
Attachments – Paperclip
Pagination – Kaminari
Template Engine – Haml
UI – Twitter Bootstrap

52. Ruby Resources
main site
http://www.ruby-lang.org
tutorials
http://tryruby.org
http://ruby.learncodethehardway.org/
http://mislav.uniqpath.com/poignant-guide/

53. Rails Resources
main site
http://rubyonrails.org/
tutorials
http://ruby.railstutorial.org/
http://railsforzombies.org/
Windows Installer
http://railsinstaller.org/

54. Thank You For
Listening!
Philippine Ruby Users Group:
http://pinoyrb.org
https://groups.google.com/forum/#!forum/ruby-phil
me: http://bryanbibat.net | @bry_bibat