A brief introduction to Ruby programming language using some modern programming techniques and concepts.

1. Introduction to Ruby & Modern
Programming
Christos Sotirelis
www.sotirelischristos.com
December 2015

2. What am I doing here?

3. Our goal
 Meet Ruby and modern programming
 See how to benefit from Ruby
 Learn some Ruby basics
 Prepare to dive in Rails and modern web applications
 Keep the journey going

4. What is Ruby?

5. What is Ruby?
o Dynamic, interpreted, object-oriented programming
language written in C
o Expressive and declarative
o Invented by Yukihiro “Matz” Matsumoto in 1996 but
was popularized by Ruby on Rails in 2005
o Influenced by Perl, Python, Smalltalk, Eiffel, Ada, Lisp
o Designed to make programmers happy
o Open source

6. Why another language?

7. Why Ruby?
o Very well documented
o Highly readable
o Multi-paradigm
o Memory-managed and garbage-collected
o Built-in data structures
o Many more..

8. Getting on Cloud9
 https://c9.io/
 “SIGN UP” or “TRY IT NOW”
 Create a new workspace
 “Ruby on Rails Tutorial” template

9. The IRB
On Cloud9’s terminal: irb
Alternatively, save your Ruby code with .rb
extension and run with: ruby <file.rb>

10. Ruby is multi-paradigm

11. Procedural

12. Procedural + Object-Oriented

13. OO Ruby
 In a website, a User is a class
 It has fields, such as an email and a password
 It also has methods, such as register() and login()
 We can create objects (or instances) of a class, such
as user1, user2 and so on
 We can also access their fields, like user1.email and
user1.password
 Most importantly, we can use class methods on our
objects, like user2.register() or user2.login()
 In a traditional, non-OO system, we would have to use
many different variables and methods for every user
we had (too much space)

14. OO Ruby

15. Procedural + Object-Oriented + Functional

16. Functional?

17. Chained methods

18. Java VS. Ruby
In Ruby, everything is an object!

19. is actually that:
So this..

20. Tell me 10 random methods of you
Hey 10, what are you?

21. More (expressive) Ruby..

22. Syntactic sugar

23. Parentheses and semicolons are optional

24. Dynamic typing

25. Duck typing
“If it walks like a duck and quacks like a duck, then
it must be a duck.”

26. Ruby conditionals

27. Ruby conditionals

28. Ruby loops
..much better this way!
Too old style..

29. Ranges :D
Homemade alphabet

30. Methods
Multiple returns plus
syntactic sugar

31. Arrays & hashes

32. Arrays & hashes
 Arrays and hashes in Ruby are more like collections
 They respond to same methods
 We can think of arrays as dynamic lists
 Arrays are also type-agnostic

33. Arrays

34. Hashes
 Hashes are pairs of unique keys and values
 Hashes (and arrays) include the Enumerable mixin

35. Advanced concepts

36. Open classes
 In Ruby, classes are never closed: methods can always
be added to an existing class
 Applies to all classes, including the standard, built-in
classes
 If not cautious, bad things are bound to happen

37. Metaprogramming & reflection
 In Ruby, code can be programmatically modified at
runtime
 Writing code that writes code
 Classes and methods know about themselves

38. Metaprogramming & reflection

39. Ruby gems
 Libraries in Ruby are called gems
 Can be installed with “gem install capistrano”
 View locally installed gems with “gem list”

40. Simple deck with cards
Save as cards.rb and run with “ruby cards.rb”

41. Look up on your own
 method_missing
 Mixins
 Introspection
 Exceptions
 Procs & lambdas
 Multithreading
 File I/O
 Sockets
 Regular expressions
 (Unit) Testing

42. More about Ruby
 https://www.ruby-lang.org
 https://www.codecademy.com
 http://www.tryruby.org
 http://www.ruby-doc.org
 http://www.sitepoint.com/ruby

43. Thank you!
you.ask(me) or you.email(me) if any_questions?
you.applause
www.sotirelischristos.com