The document outlines why the author started using Ruby and provides an overview of the Ruby programming language and Ruby on Rails web application framework. It discusses how Ruby is a dynamic, object-oriented language designed to be elegant and efficient. Ruby on Rails makes it easy to build database-backed web applications according to the MVC pattern. The document also covers the Ruby ecosystem including interpreters, frameworks, libraries and tools, and discusses the future of Ruby and Rails.

1. Why Ruby?
{
my story how I started learning and using Ruby

2. Plan
1. About me
2. Why Ruby?
3. What is Ruby?
4. Ruby on Rails
5. Ruby-world Ecosystem
6. Future
7. Questions

3. About me
Igor Kasyanchuk
Education: National University of Oil and Gas, PZ-01-1
Worked at: Eleks, SoftServe, freelancing, own projects
Completed projects: 20+
Used: Java, Visual C++, C++ Builder
Using: Ruby, Ruby on Rails, HTML/CSS/JS/etc
Working now: in SoftServe as Ruby, Ruby on Rails Team/Tech Lead

4. Why Ruby?
I was tired of …
... and many other things

5. Why Ruby?
And I met Ruby …
say = "I love Ruby"
puts say
say['love'] = "*love*"
puts say.upcase
5.times { puts say }

6. What is Ruby?
Ruby is a dynamic, reflective, object-oriented,
general-purpose programming
language. It was designed and developed in
the mid-1990s by Yukihiro "Matz"
Matsumoto in Japan.
… from Wikipedia
Q: What other dynamic languages do you know?

7. What is Ruby?
Ruby is a dynamic, reflective, object-oriented,
general-purpose programming
language. It was designed and developed in
the mid-1990s by Yukihiro "Matz"
Matsumoto in Japan.
… from Wikipedia
What other dynamic languages do you
know? – PHP, Python, Node.JS

8. Ruby is
• Dynamic programming language
• Less is more, efficient code, easy to read, elegant
• One of the best language for creating startups (Twitter,
Groupon, Airbnb, Slideshare)
• Companies using it: HP, Twitter, Intel, NASA, HULU, Groupon,
Airbnb, Github, Slideshare
• Has ~90K libraries, which were downloaded ~3.8M times
• Killer app: Ruby on Rails

9. Also, Ruby is
http://hyperpolyglot.org/scripting
PHP
$a = [1, 2, 3]
min($a)
max($a)
Python
min([1, 2, 3])
max([1, 2, 3])
Ruby
[1, 2, 3].min
[1, 2, 3].max
Java
import java.util.Arrays;
import java.util.Collections;
import org.apache.commons.lang.ArrayUtils;
public class MinMaxValue {
public static void main(String[] args) {
char[] a = {'3', '5', '1', '4', '2'};
List b = Arrays.asList(ArrayUtils.toObject(a));
System.out.println(Collections.min(b));
System.out.println(Collections.max(b));
}
}

10. Syntax
1. Overview
2. Loops
3. Blocks
4. Classes, Mixins
5. OOP in Ruby
6. “Dynamicity”

11. Overview
puts "Hello World"
"LOREM".downcase
"lorem".length
"abcd".split("")
if /1999/.match(s)
puts "party!"
end
t = Time.now
a = [1, 2, 3, 4]
a[-1]
Time.now.strftime("%Y-%m-%d %H:%M:%S")
role = :admin
ROLES = [‘admin’, ‘user’]
(1..1_000_000).each do |i|
…
end
x = 1000
user = user.new unless user

12. Loops
i=0
while i < 3
print i, " whilen”
i += 1
end
for ss in 0..2
print ss, " for doubledotn”
end
array=['zero', 'one', 'two', 'three', 'four', 'five']
array.each{|ss| print ss, " array.eachn"}
array[0,3].each{|ss| print ss, " array_first_three.eachn”}

13. Blocks
def simple
puts 'Here comes the code block!’
yield
puts 'There was the code block!’
end
Now:
simple { puts 'Hooray! The code block is here!' }
Result:
Here comes the code block!
Hooray! The code block is here!
There was the code block!

14. Classes, Mixins
class Greeter
def initialize(name)
@name = name.capitalize
end
def salute
puts "Hello #{@name}!"
end
end
# Create a new object
g = Greeter.new("world")
# Output "Hello World!"
g.salute
# Creating mixin
module Log
def log(message)
puts message
end
end
# Creating class
class User
include Log
end
user = User.new
user.log “hello user”

15. OOP in Ruby
1. Everything is an object (numbers, strings, classes, everything…)
2. Class can inherit only from one parent (single inheritance)
3. You can use mixins (in other languages eq. to interfaces + implementation)
5.times do |e|
puts “hello world”
end
[1,0,6,9,3,5].select{|e| e > 3}.collect{|e| e*2}.min.times do |e|
puts e
end

16. “Dynamicity”
class Greeter
def initialize(name)
@name = name
end
def method_missing(e)
greeting = e.to_s.capitalize
"#{greeting} #{@name}"
end
end
g = Greeter.new("Igor")
puts g.hello
=> Hello Igor
1. Strong reflection
2. eval
3. method_missing
4. send
5. overload, override anything
6. modify, remove, add methods on the fly

17. Ruby on Rails
Ruby on Rails, or simply Rails, is an open
source web application framework written
in Ruby. Rails is a full-stack framework that
emphasizes the use of well-known software
engineering patterns and paradigms,
including convention over configuration
(CoC), don't repeat yourself (DRY), the active
record pattern, and model–view–controller
(MVC).
… Wikipedia
Author:
David Heinemeier Hansson
Since 2004
From Denmark

18. Ruby on Rails
1. Built on Ruby
2. Web Application Framework
3. Blog in 15 minutes
4. MVC, CoC, DRY

19. Built on Ruby
To work with Ruby on Rails you just need to
install Ruby our your computer and then
install ”rails” as gem.
gem install rails

20. Web Application Framework
• HTML/HAML/SLIM…
• CSS/SCSS/SASS…
• JS/CoffeeScript….
• MySQL/Postgres/Mongo….
• REST/API
• Testing
• Java, C, Resque, Sphinx, ElasticSearch, etc

21. Blog in 15 minutes
Check it!

22. Blog in 15 minutes
Check it!

23. MVC
• Object Relation Mapping
• Database Agnostic
• CRUD simple
• Class to Table, Row to Object
class User < ActiveRecord::Base
has_many :photos
end
User.first => SELECT `users`.* FROM `users` ORDER BY `users`.`id` ASC LIMIT 1
User.find(2) => SELECT `users`.* FROM `users` WHERE `users`.`id` = 2 LIMIT 1
User.find_by(first_name: "igor") =>
SELECT `users`.* FROM `users` WHERE `users`.`first_name` = 'igor' LIMIT 1
user = User.find(1)
user.photos => SELECT photos.* from photos where user_id = 1

24. MVC
Connecting view and model
сlass UsersController < ApplicationController
def index
@users= User.all
end
end

25. MVC
Generating HTML (using SLIM)
table
- @users.each do |user|
tr
td= user.first_name
td= user.last_name

26. CoC
Convention over Configuration

27. DRY
# def easy_ui
# self.easy.presence || 'EASY'
# end
# def medium_ui
# self.medium.presence || 'MEDIUM'
# end
# def hard_ui
# self.hard.presence || 'HARD'
# end
[:easy, :medium, :hard].each do |field|
define_method "#{field}_ui" do
[field].presence || field.to_s.upcase
end
end

28. Ruby-world Ecosystem
Interpreters: MRI, jRuby, Rubinius, …
Frameworks: Ruby on Rails, Sinatra, E, …
Editors: Sublime, RubyMine, VIM, …
Tests: Rspec, Selenium, Capybara, minitest
Servers: Passenger, Unicorn, Puma, Thin, …
Libraries (gems): for any tasks … xml, video, image, data processing,
API, ….
Mobile App: RubyMotion – create native iOS apps in Ruby
Community: Google groups, stackoverflow, rubyclub.com.ua, …
And more …. Github, BitBucket, CoffeeScript, SASS/SCSS,
HAML/SLIM,
OAuth, Emails, Ajax, Books(30+), integration with Backbone (and
other JS frameworks), payments (PrivatBank has gem), …

29. Future
• Ruby 2.2 is coming
• Rails 4.2 is coming + Rails 5 branch is created
• Many job offers
• New Projects, challenges, startups

30. Questions?
skype: igorkasyanchuk
feel free to contact me 

31. Thank you
and welcome to Ruby world