Ruby An Introduction

84
Ruby – An Introduction T.Shrinivasan [email protected] Indian Linux User Group, Chennai FossConf'08

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My Ruby Presentation on FossConf 2008,

Transcript of Ruby An Introduction

Page 1: Ruby An Introduction

Ruby – An [email protected]

Indian Linux User Group, Chennai

FossConf'08

mailto:[email protected]
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Ruby is a Programming Language

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There are so many 

Programming Languages.

Why Ruby?

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Ruby is simple and beautiful

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Ruby is Easy to Learn

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Ruby is Free Open Source Software

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Ruby on Rails – Web Framework

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RAA● Ruby Application Archive● 1648 projects

● http://raa.ruby-lang.org

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Rubyforge● 5070 projects and libraries

● http://rubyforge.org/

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Can do● Text Handling● System Administration● GUI programming● Web Applications● Database Apps● Scientific Applications

● Games● NLP

● ...

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History

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RubyYukihiro “Matz” Matsumoto

JapanFebruary 24, 1993

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 Perl  Java  Python  Ruby  PHP1987       1991         1993  1995

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        What is Ruby?

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Ruby is…

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.

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Quick and Easy●      Intrepreted Scripting Language●      Variable declarations are unnecessary●      Variables are not typed●      syntax is simple and consistent●      memory management is automatic

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Object Oriented Programming●      Everything is an object●      classes, methods, inheritance, etc.●      singleton methods●      "mixin" functionality by module●      iterators and closures

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Examples!

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5.times { print “Ruby! " }

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Ruby! Ruby! Ruby! Ruby! Ruby!

5.times { print “Ruby! " }

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Everything isan object

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100.next

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100.next101

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“I love Ruby” .reverse.capitalize

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“I love Ruby”

.reverse.capitalize

“Ybur evol i”

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3.hours.from_now

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3.hours.from_now

Thu Jan 19 22:05:00 Eastern Standard Time 2006

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Conventions

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Variables

colored_index_cards

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Class Names

Person

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Symbols

:street_name

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Instance Variables

@school_name

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Constants

Kilograms_Per_Pound

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Input

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puts “What is Your name?”

name = gets

name = name.chomp

puts "Hello" + name + " .Welcome"

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            Flow

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if ( score >= 5000 ) puts “You win!”elsif ( score <= 0 ) puts “Game over.”else puts “Current score: #{score}”end

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puts “PASS” if mark > 35

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                    Loop

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count = 05.times docount += 1puts "Count =" + count.to_s

end

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Count = 1Count = 2Count = 3Count = 4Count = 5

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count = 0while count < 10puts "Count = " +count.to_scount += 1

end

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Blocks

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1.upto(5) { |x| puts x }

12345

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5.downto(1) do |time| print “#{time}... ” puts “!” if time <= 3end

5... 4... 3... !2... !1... !

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Array

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Arraynumbers = [ "zero", "one", "two", "three", "four" ]  

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Arraynumbers = [ "zero", "one", "two", "three", "four" ]  

>> numbers[0]

=> "zero"

>> numbers[4]

=> "four"

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Arraynumbers = [ "zero", "one", "two", "three", "four" ]

>> numbers[3].upcase

=> "THREE"

>> numbers[3].reverse

=> "eerht"

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Sort Arrayprimes = [ 11, 5, 7, 2, 13, 3 ]

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Sort Arrayprimes = [ 11, 5, 7, 2, 13, 3 ]

primes.sort

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Sort Arrayprimes = [ 11, 5, 7, 2, 13, 3 ]

primes.sort

=> [2, 3, 5, 7, 11, 13]

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Sort Arraynames = [ "Shrini", "Bala", "Suresh", "Arul"]

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Sort Arraynames = [ "Shrini", "Bala", "Suresh", "Arul"]

names.sort

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Sort Arraynames = [ "Shrini", "Bala", "Suresh", "Arul"]

names.sort

=>["Arul", "Bala", "Shrini", "Suresh"]

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More on Arrays● Reverse● Length● Delete● Join● Find● More than 100 methods

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Hashes

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menu = { :idly => 2.50, :dosai => 10.00, :coffee => 5.00, :ice_cream => 5.00}

menu[:idly]2.50

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Methods

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Methods

def say_hello(name) result = “Hello, #{name}!” return resultend

puts say_hello(“world”)

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Methods

def say_hello(name) “Hello, #{name}!”end

puts say_hello(“world”)

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Class

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Classesclass MathWhiz

def say_square(value) puts value * value

end

end

sam = MathWhiz.new

sam.say_square(5)

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Inheritance

class Dog < Animal @catagory = “mammal” @legs = 4end

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Module

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Modules

module Trig PI = 3.141592654 def Trig.sin(x) # .. end def Trig.cos(x) # .. endend

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Modules

require "trig"y = Trig.sin(Trig::PI/4)0.707106780551956

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Attributes

class PlainOldRubyObject attr_accessor :food, :drinks attr_reader :advice attr_writer :write_onlyend

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Scopeclass Poet #public by default def poetry end

protected def family_legacy end

private def hopes_and_dreams endend

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THE ENDof code :-)

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How to Learn?

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irb● interactive ruby● A ruby Shell● Instance response● learn as you type

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Web sites

Web Sites

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http://ruby­lang.org

www.ruby­lang.org

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www.rubyforge.net

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http://www.ruby­forum.com/

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Training Centers

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Ruby User Groups

[email protected]

● Mailing List● Meetings● Tutorial Sessions

Join Today

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Copyright (c)  2008   Permission is granted to copy, distribute and/or modify this document  under the terms of the GNU Free Documentation License, Version 1.2

  or any later version published by the Free Software Foundation.

http://www.gnu.org/copyleft/fdl.html  

We thank                         and                               for Photos


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