Ruby

Programming Lan-guage

Introduction28 Jun 2015

Kwangshin Oh

kwangshin@gmail.com

http://kwangshin.pe.kr

Seven Languages in Seven WeeksA PragmaticGuide toLearningProgrammingLanguages

By Bruce A. Tate

Why New Programming Lan-guage?“Learning a new programming language will show you

new ways of thinking, and new approaches to problem solving

that will help you be a better programmer in any language.”

- Pragmatic Bookshelf

“Ultimately, programming is about understanding, and understanding is about ideas. So, exposure to new ideas is essential to a deeper understanding of what

programming is all about.”

- Foreword By Joe Armstrong, creator of Erlang

Agenda Ruby is… History & Why?

With a Spoonful of Sugar So, Ruby is… Ruby: Interpreted Language

Ruby: Interpreted Language – Example Compare: Compiled Language - Java

Ruby: Object-Oriented Language Ruby: Pure Object-Oriented Language

Ruby: Dynamically Typed Language What is Duck Typing? Ruby: Duck Typing Code Example

Download & Installation Ruby Code Reference

Ruby is…Programming Language!

DynamicOpen Source

Focus on…SimplicityProductivity

Has an elegant syntaxNatural to readEasy to write

Image Source: Ruby Programming Language

History & Why?Ruby’s Creator

Yukihiro “Matz” Matsumoto

Created in about 1993Motivation

The primary motivation was to amuse himself!Just a hobby at the beginningNew object-oriented language that combines

characteristics from Lisp, Smalltalk and PerlTo enhance programmers’ productivity

“Ruby is simple in appearance, but is very complex inside, just like our human body.”- Matz, speaking on the Ruby-Talk mailing list, May 12th, 2000.

Image Source: Ruby Everywhere

With a Spoonful of SugarRuby with more syntactic sugar

Makes code easier to read and write

Focus on the efficiency of the pro-

grammers

“A spoonful of sugar makes the medicine go down.”

Mary Poppins

Image Source: Disney Wiki – A Spoonful of Sugar

So, Ruby is… Interpreted Language

Ruby code is executed by an interpreter

Object-Oriented LanguageEncapsulationInheritancePolymorphism

Dynamically Typed LanguageTypes are bound at execution time

Image Source: Skillcrush - Ruby

Interactive

Console

Ruby File (*.rb)

Ruby: Interpreted Language

Image Source: http://www.iconsdb.com, http://dryicons.com and http://findicons.com

Ruby Interpreter

Interactive

Console

Ruby File (Ha.rb)

Ruby: Interpreted Language - Example

D:\Ruby22\bin>type Ha.rb3.Times do print “Ha “endD:\Ruby22\bin>ruby Ha.rbHa Ha HaD:\Ruby22\bin>

D:\Ruby22\bin>ruby3.Times do print “Ha “end^DHa Ha HaD:\Ruby22\bin>

Compare: Compiled Language - Java Java Source

File (*.java)

JavaCompiler

Java Class File (*.class)

JRE(Java Runtime Environment)

Ruby: Object-Oriented LanguageEncapsulation

[State & Behavior] : Packaged together

Inheritance[Class Tree] : Object types are organized

Polymorphism[Many Forms]

: Objects can be shown

Image Source: What Is an Object?

Image Source: What Is Inheritance?

Image Source: Object-Oriented Concepts

Ruby: Pure Object-Oriented Language

Ruby Programming LanguageEverything is an object!

Compare: Java Programming LanguagePrimitive types (int, char, ……) are not objects!

D:\Ruby22\bin>irbirb(main):001:0> 4=> 4irb(main):002:0> 4.class=> Fixnumirb(main):003:0> 4 + 4=> 8irb(main):004:0> 4.methods=> [:to_s, :inspect, :-

@, :+, ∙∙∙∙∙∙, :__id__]irb(main):005:0>

Ruby: Dynamically Typed Lan-guage

Types are bound at execution time

FlexibilityExecution Safety

Types are bound at compile time

Flexibility Execution Safety

Dynamically Typed

Statically Typed

Java

What is Duck Typing?Quacks like a duck

Swims like a duck

Walks like a duck

Call it a duck

“When I see a bird that walks like a duck and swims like a duck and quacks like a duck, I call that bird a duck.” - James Whitcomb

RileyImage Source: https://www.iconfinder.com and http://www.vectors4all.net/

Ruby: Duck Typing Code Exam-ple

D:\Ruby22\bin>irbirb(main):001:0> i = 0=> 0irb(main):002:0> a = ['100', 100.0]=> ["100", 100.0]irb(main):003:0> while i < 2irb(main):004:1> puts a[i].to_iirb(main):005:1> i = i + 1irb(main):006:1> end100100=> nilirb(main):007:0>

We consider this to_i method as quack!

Duck typing doesn’t carewhat the underlying type might

be (whether string or float).

string

float

Download & Installation Current Stable Version

Ruby 2.2.2 (As of 28 Jun 2015)

WindowsRubyInstaller - http://rubyinstaller.org/downloads/

OS XHomebrew - http://brew.sh/

Debian GNU/Linux and Ubuntuapt – command : $ sudo apt-get install ruby-full

CentOS, Fedora, and RHELyum – command :$ sudo yum install ruby

Ruby: Sample Code

D:\Ruby22\bin>rubyproperties = ['object oriented', 'duck typed', 'productive', 'fun']properties.each {|property| puts "Ruby is #{property}."}^DRuby is object oriented.Ruby is duck typed.Ruby is productive.Ruby is fun.D:\Ruby22\bin>

Ruby Code: Hello World!

D:\Ruby22\bin>irbirb(main):001:0> puts 'Hello World!'Hello World!=> nilirb(main):002:0> language = 'Ruby'=> "Ruby"irb(main):003:0> puts "Hello, #{language}"Hello, Ruby=> nilirb(main):004:0> language = 'my Ruby'=> "my Ruby"irb(main):005:0> puts "Hello, #{language}"Hello, my Ruby=> nilirb(main):006:0>

Ruby’s Interactive Console

<One Quote String>Interpreted Literally

<Two Quotes String>

String Evaluation

Ruby Code: Comparison Opera-tors

D:\Ruby22\bin>irbirb(main):001:0> x = 4=> 4irb(main):002:0> x < 5=> trueirb(main):003:0> x > 4=> falseirb(main):004:0> false.class=> FalseClassirb(main):005:0> true.class=> TrueClassirb(main):006:0> puts 'X value is equal to 4.' if x == 4X value is equal to 4.=> nilirb(main):007:0>

Everything is an object in Ruby!

Ruby Code: Loops – until & while

D:\Ruby22\bin>irbirb(main):001:0> x = 5=> 5irb(main):002:0> x = x - 1 until x == 1=> nilirb(main):003:0> x=> 1irb(main):004:0> while x < 5irb(main):005:1> x = x + 1irb(main):006:1> puts xirb(main):007:1> end2345=> nil

Ruby Code: Expressions - true & false

D:\Ruby22\bin>irbirb(main):001:0> puts '1 is true in Ruby' if 11 is true in Ruby=> nilirb(main):002:0> puts 'String is true in Ruby' if 'Kwangshin Oh'(irb):2: warning: string literal in conditionString is true in Ruby=> nilirb(main):003:0> puts '0 is also true in Ruby' if 00 is also true in Ruby=> nilirb(main):004:0> puts 'The false is false in Ruby' if false=> nilirb(main):005:0> puts 'The nil is false in Ruby' if nil=> nilirb(main):006:0>

Everything( but nil and false ) evaluate to true!

Reference Seven Languages in Seven Weeks: A Pragmatic Guide to Learning Programming Lan-

guage by Bruce A. Tate https://pragprog.com/book/btlang/seven-languages-in-seven-weeks

Ruby Programming Language https://www.ruby-lang.org/

Ruby-Talk mailing list, May 12th, 2000 http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/2773

Disney Wiki – A Spoonful of Sugar http://disney.wikia.com/wiki/A_Spoonful_of_Sugar

Matz にっき (Matz Diary) http://www.rubyist.net/~matz/

The Java™ Tutorials - Object-Oriented Programming Concepts https://docs.oracle.com/javase/tutorial/java/concepts/index.html

Duck typing https://en.wikipedia.org/wiki/Duck_typing