An overall approach of Ruby. Presentation given at a paradigm programming course at FEUP ’12.

1. RUBY Felipe Schmitt
an overall approach PPRO@FEUP 2012

2. @schmittfelipe

3. CONTENTS
• Ruby’s history
• What is Ruby?
• Programming paradigms insight
• How it works?
• Ruby’s usage
• Where can I learn more?

4. RUBY’S HISTORY

5. Timeline: 1993 - 2000
Yukihiro Matsumoto
• Created in 1993
• Popular only in Japan
• All documentation written in Japanese

6. Timeline: 2000 - 2004
• First english language book published in
2000
• Ruby has gained a lot of interest in Agile
Development community but still
unknown elsewhere

7. Timeline: 2004 - Today
• Ruby on Rails, the framework that
allowed ruby to step up to the spotlight
• Ruby v1.9
• Core 100% documented
• 96 standard libraries

8. WHAT IS RUBY?

9. “I wanted a scripting language that was more powerful than Perl, and more object-
oriented than Python. That's why I decided to design my own language.”
-Yukihiro Matsumoto

10. INFLUENCES
Lisp
Python
Ruby
CLU Perl
Smalltalk

11. WHAT IS RUBY?
•A dynamic, open source programming language with a focus on simplicity
and productivity. It has an elegant syntax that is natural to read and easy to
write.

12. PROGRAMMING PARADIGMS

13. Multi-paradigm programming language
• Functional
• Object oriented
• Imperative
• Reflective
It also has a dynamic type system and automatic memory management;

14. HOW IT WORKS?

15. VS

16. Getting Started
HelloWorld.java
class HelloWorldApp {
public static void main(String[] args) {
System.out.println("Hello World!");
}
}

17. Getting Started
HelloWorld.rb
puts “Hello World!”
No main statement
No semicolons
( )’s are optional

18. Object
Java
String s = String.ValueOf(1);

19. Object
Java
String s = String.ValueOf(1);
Ruby
s = 1.to_s

20. Object
Java
String s = String.ValueOf(1);
Ruby
s = 1.to_s
Everything is an object!

21. Types
Java
public void foo(ArrayList list) {
list.add(“foo”);
}

22. Types
Java
public void foo(ArrayList list) {
list.add(“foo”);
}
Ruby
def foo list
list << “foo”
end

23. Types
Java
public void foo(ArrayList list) {
list.add(“foo”);
}
Ruby
(?) return
def foo list
list << “foo”
end
(?) Object type

24. Types
If list is a string: ‘foo’
If list is an array: [‘foo’]
If list is a stream: foo is written to stream
Ruby
def foo list
list << “foo”
end

25. Duck Typing
“If it walks like a duck and quacks like a duck, it must be a duck.”
- Pragmatic Dave Thomas

26. Iterators
Objects manage their own transversal
Ruby
array.each { |item|
puts item
}
No for loops:
Loops N + 1 errors

27. Open classes
Ruby
class Array
def average
inject do |sum, var|
sum + var
end / size
end
end
nums = [1,2,3,4,5]
puts nums.average #prints: 3
Existing classes can be modified at any time.

28. WHO’S USING RUBY?

30. RECAP
Influences Style Overall
• Perl’s syntax • Simplicity • Everything is an object
• Smalltalk’s semantics • Productivity • Flexible
• Python’s design philosophy • Elegant syntax • Large standard library
“Actually, I'm trying to make Ruby natural, not simple.”
- Matz

31. MORE STUFF
Books
Beginning Ruby: From Novice to Professional (2009)
The Expert’s Voice by Peter Cooper
The Ruby Programming Language (2008)
O’reilly by David Flanagan and Yukihiro Matsumoto
Agile Web Development with Rails (2011) 4th edition
Pragmatic Programmers by Sam Ruby, Dave Thomas and David Heinemeier Hansson
Web
http://www.ruby-lang.org/
http://www.slideshare.net/mbowler/ruby-for-java-programmers
http://www.slideshare.net/vishnu/the-top-10-reasons-the-ruby-programming-language-sucks
http://www.fincher.org/tips/Languages/Ruby/