Ruby.new @ VilniusRB

Vilniaus Ruby bendruomenė

Ruby.newVidmantas Kabošis @ VilniusRB.new

2014-11-22

@vidmantastwitter/github

Other companies (LT)

Worldwide companies

1995

2004

2.1.5

2.1.x

2.x.x

x.x.x

Why?

Ruby is designed for expressiveness & happiness

Open source, from the heart: licensing, friction, ecosystem1

1 - http://blog.codinghorror.com/why-ruby/

One of the many

C Java

Objective-CC++

C#PHP

Python

Javascript

Perl

VBR

SQL

RubyDelphi

F#

One of the many interpreted

C Java

Objective-CC++

C#PHP

Python

Javascript

Perl

VBR

SQL

RubyDelphi

F#

Ruby

Interpreted

Dynamic

Object-oriented

General purpose

Types

0 == "0"

Dynamically but strongly typed

Types

0 == "0".to_i

Dynamically but strongly typed

Vilniaus Ruby bendruomenė

describe "WiFi" do ssid "ruby" password "vilnius"end

More warmup examples

"vilniusrb".length

[1, 2, 3].include?(3)

"vilniusrb".include?("rb")

print "YOLO" if 1 > 2

2 * 2 + 2

Method definition

def hello puts "Hello Ruby"end

Calling the method

hello

Calling the method

hello

Hello Ruby

Calling the method

hello()

Hello Ruby

Method with parameter

def hello(name) puts "Hello #{name}"end

Calling the method & param

hello("PHP")

Hello PHP

Method with default param

def hello(name = "Ruby") puts "Hello #{name}"end

Calling the method & param

hello

Hello Ruby

Calling the method & param

hello ".NET"

Hello .NET

Flow control: if

if [1, "rb", nil].count >= 3 world_peace

else depression_with_chocolateend

The truth & the lies

false

nil

Check the truth

[]

0

Iteration

s = "Vilnius Ruby community".split

Iteration

s = ["Vilnius","Ruby", "community"

]

Iteration: the classics

for (i = 0; i < s.length; i++) {// do something with s[i]

}

Iteration: the Ruby way

s.each do |word| # do something with word puts word.upcaseend

Blocks

s.each do |word| # do something with word puts word.upcaseend

Blocks: implementation

def eachsize.times do |i|

yield(self[i])end

end

Blocks: implementation

def each size.times { |i| yield(self[i]) }end

Blocks: implementation

def each(&block)size.times do |i|

block.call(self[i])end

end

Enumerable

.map .max

.inject .min

.reject .partition

.all? .select

.any? .sort

.detect .first

Enumerable in action

[10, 5, 7] .map { |n| n * 2 } .select { |n| n > 10 } .sort

.first

Enumerable in action

[10, 5, 7] .map { |n| n * 2 } # [20, 10, 14]

.select { |n| n > 10 } # [20, 14]

.sort # [14, 20]

.first # 14

Objects

Everything is an object

Really

*Everything*

Classes are instructions

Objects - real instances

Classes are instructions

class Phone def initialize(name)

@name = name end

def bends? @name == :iphone endend

Objects - real instances

iphone = Phone.new(:iphone)iphone.bends? # true

nokia = Phone.new(:3310)nokia.bends? # false

It’s about time for magic!

Classes are always open

class String def last_capitalize reverse.capitalize.reverse endend

Classes are always open

class String def last_capitalize reverse.capitalize.reverse endend

"vilniusrb".last_capitalize

"vilniusrB"

Define methods, everywhere

vrb = "vilniusrb"

def vrb.rb_capitalize gsub("rb", "RB")end

vrb.rb_capitalize

"vilniusRB"

Missing a method?

class Phone def method_missing(mname, *args, &block) puts "I don’t know about `#{mname}`" puts caller.first endend

Missing a method?

def method_missing(mname, *args, &block) puts "I don’t know about `#{mname}`" puts caller.firstend

Phone.new.flips?

I don’t know about `flips?`/my/file/path/phone.rb:42:in `<main>`

Who’s who?

class class Phone def initialize(&block) instance_eval(&block) end

def answer! puts "Howdy?" endend

Who’s who?

def initialize(&block) instance_eval(&block)enddef answer! puts "Howdy?"end

Phone.new { answer! }

The Metaprogramming

.instance_eval

.class_eval

.define_method

.send

.method_missing

.instance_variable_set / get

Ruby

Interpreted

Dynamic

Object-oriented

General purpose

Ruby

Interpreted

Dynamic

Object-oriented

General purposeFUN

And profit!

Time for fun!

house = House.new(2, 4, 5)house.floors # 2house.volume # Volume is 120 cubic meters.house.needs_elevator? # Yes

Time for fun! And magic

describe "WiFi" do ssid "ruby" password "vilnius"end

# { "WiFi": { "ssid": "ruby", "password": "vilnius" } }

“Answers”

bit.ly/vilniusrb-1

bit.ly/vilniusrb-2

Open source & gems

gem install credit_card_validator

require "credit_card_validator"number = '1111 2222 3333 4444'CreditCardValidator::Validator.valid?(number) # false

RubyA programmer’s best friend

Vilniaus Ruby bendruomenė

Questions.any?