RUBYan overall approach

Felipe Schmitt PPRO@FEUP 2012

@schmittfelipe

CONTENTS

• Ruby’s history

• What is Ruby?

• Programming paradigms insight

• How it works?

• Ruby’s usage

• Where can I learn more?

RUBY’S HISTORY

Yukihiro Matsumoto

Timeline: 1993 - 2000

• Created in 1993

• Popular only in Japan

• All documentation written in Japanese

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

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

WHAT IS RUBY?

“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

INFLUENCES

Smalltalk

Perl

Python

CLU

Lisp

Ruby

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.

PROGRAMMING PARADIGMS

• Functional

• Object oriented

• Imperative

• Reflective

It also has a dynamic type system and automatic memory management;

Multi-paradigm programming language

HOW IT WORKS?

VS

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

HelloWorld.java

Getting Started

puts “Hello World!”

HelloWorld.rb

No main statement

No semicolons

Getting Started

( )’s are optional

Object

String s = String.ValueOf(1);Java

Object

s = 1.to_sRuby

String s = String.ValueOf(1);Java

Everything is an object!

Object

String s = String.ValueOf(1);Java

s = 1.to_sRuby

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

Java

Types

Types

def foo listlist << “foo”

end

Ruby

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

Java

Types

(?) return

(?) Object type

def foo listlist << “foo”

end

Ruby

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

Java

If list is a string: ‘foo’

If list is an array: [‘foo’]

If list is a stream: foo is written to stream

Types

def foo listlist << “foo”

end

Ruby

Duck Typing

“If it walks like a duck and quacks like a duck, it must be a duck.”

- Pragmatic Dave Thomas

Loops N + 1 errors

Iterators

No for loops:

array.each { |item| puts item }

Ruby

Objects manage their own transversal

Open classes

class Array def average inject do |sum, var|

sum + varend / size

endend

nums = [1,2,3,4,5]puts nums.average

Ruby

Existing classes can be modified at any time.

#prints: 3

WHO’S USING RUBY?

RECAP

• Perl’s syntax

• Smalltalk’s semantics

• Python’s design philosophy

Influences• Everything is an object

• Flexible

• Large standard library

Overall• Simplicity

• Productivity

• Elegant syntax

Style

“Actually, I'm trying to make Ruby natural, not simple.”- Matz

http://www.fincher.org/tips/Languages/Ruby/

MORE STUFF

http://www.slideshare.net/vishnu/the-top-10-reasons-the-ruby-programming-language-sucks

http://www.slideshare.net/mbowler/ruby-for-java-programmers

http://www.ruby-lang.org/

Agile Web Development with Rails (2011) 4th edition Pragmatic Programmers by Sam Ruby, Dave Thomas and David Heinemeier Hansson

Books

Web

The Ruby Programming Language (2008)O’reilly by David Flanagan and Yukihiro Matsumoto

Beginning Ruby: From Novice to Professional (2009)The Expert’s Voice by Peter Cooper