My slides for DevCon @ Y4iT 2011 lightning talk

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. Bonus Example:
Scale the
Twitter Clone

53. Thank You For
Listening!
Philippine Ruby Users Group:
http://pinoyrb.org
me: http://bryanbibat.net | @bry_bibat