AIESEC 26 Apr 2013

RUBY
Vlad Verestiuc
http://about.me/vvlad

“My conscience won’t let me call Ruby a computer
language. That would imply that the language works
primarily on the computer’s terms. That the
language is designed to accommodate the
computer, first and foremost. “
- Why's (poignant) Guide to Ruby
“Ruby is designed to make programmers happy”
- Matz (Yukihiro Matsumoto)

class OrderItem < ActiveRecord::Base
belongs_to :account
belongs_to :order
belongs_to :product
has_many :categories
validates :name, presence: true
validates :quantity, numericality: { greater_than_or_equal_to: 1 }
validate :price_value
before_create :ensures_items_are_in_stock
after_create :notify_the_account_manager
end

Dar totusi ce este RUBY ?
- Este un limbaj de scripting.
- Este un limbaj untyped.
- Imperativ, OOP, Functional.
- Usor extensibil.
- Garbage Collected.

Cine il foloseste:
- Twitter
- Hulu
- Groupon
- Amazon
- Github
- 37 Signals
- Heroku
- Engineyard
- Google

Lucruri notabile despre RUBY
- Orice este un obiect
- Conventii
- Obiectele Clase
- Module
- Blocuri
- Orice are o valoare
- Orice este un obiect

Conventii:
- Variable globale ( incep cu $)
- Constante ( incep cu litera mare )
- numele functiilor ( numai litere mici, numere , _, =, ? si ! )
- variable locale ( numai litere mici, numere )
- variable de instanta ( incep cu @, numai litere mici si _)
- variable de clasa ( incep cu @@, numai litere mici si _)
- functiile care returneaza true sau false ( se termina cu ? )
- functiile care modifica starea unui obiect ( se termina cu ! )

Clase:
- Mostenire ( simpla si nu numai )
- Nu este necesar ca tot codul sa fie definit intrun singur loc. ( Class reopening )
- Domenii de vizibiliate: public, private, protected.
- Contextul de clasa ( metode de clasa )

class Smurf
def walk!
start_singing
end
def start_singing; end
end
class BabySmurf < Smurf
def walk!
take_the_peacekeeper
super #se cheama Foo#foo
make_noise
end
def take_the_peacekeeper; end
def make_noise; end
end
baby = BabySmurf.new
baby.walk!
Mostenire

class Beer
def open!
puts "I how you’ll enjoy it"
end
end
class Beer
def use(compound);end
def chilled?; [true,false].sample; end
def open!
use :liquid_nitrogen unless chilled?
puts "Now it is definitely chilled!!! Have a nice drink"
end
end
beer = Beer.new
beer.open!
Class reopening

class Human
def access_background; end
def solve_issues_for(someone); someone.issues; end
def change_underwear_of(someone); someone.underwear; end
protected
def issues; end
def underwear; end
private :underwear
end
human, good_friend = Human.new, Human.new
human.access_background
human.issues # Exceptie
human.solve_issues_for good_friend # se executa ok
human.change_underwear_of good_friend
Domenii de vizibilitate

class Human
class << self
def arise!
end
end
def self.walk!
end
def Human.kill!(what)
end
end
Human.arise!
Human.walk!
Human.kill!(:all)
Contextul de clasa

class Human
class << self
def belongs_to(something_or_somewhat);end
end
def self.has(something); end
end
def Human.acts_like(someone)
end
class Man < Human
belongs_to :humanity
has :more_legs_than_a_woman
acts_like :a_moron
end
Man.acts_like :a_moron_from_time_to_time
Contextul de clasa

class Rabbit
def hole
end
def self.foot
end
end
SpecialRabbit = Class.new(Rabbit)
SpecialRabbit.method(:foot)
#<Method: SpecialRabbit(Rabbit).foot>
SpecialRabbit.new.method(:hole)
#<Method: SpecialRabbit(Rabbit)#hole>
Orice este un obiect !!!

Module:
- Colectii de functii
- Pot fi incluse in clase.
- Pot sa extinda clase.
- Se folosesc si pentru a simula mostenirea multipla.

Includere
require 'digest/md5'
module Authenticable
def password=(value)
@encryped_password = Digest::MD5.hexdigest(value)
end
def valid_password?(password)
@encryped_password == Digest::MD5.hexdigest(password)
end
end
class User
include Authenticable
end
user = User.new
user.password = 'my_password'
user.valid_password? 'my_password'
# true
user.valid_password? 'other password'
# false

Extindere
module Runnable
def perform!(id, *arguments)
User.find(id).send(*arguments)
end
def find(id)
User.new
end
end
class User
extend Runnable
def validations(options={})
end
end
class AgreeableUnicorn
end
User.perform! 10, :validations, with: AgreeableUnicorn.new

Mostenire Multipla
module Mam
def nose
puts "small"
end
end
module Dad
def hair
puts "short"
end
end
class Me
include Mam
include Dad
def hair
puts "was"; super; puts "but now is long";
end
end
me = Me.new
me.nose
me.hair

class Knight
def shiny_armour?
false
end
end
module Armour
def shiny_armour?
true
end
end
knight = Knight.new
knight.shiny_armour?
# false
knight.extend Armour
knight.shiny_armour?
# true
Orice este un obiect !!!

3.times { |i| puts "WTF is going on here?!?!" }
winner.each do |winner|
winner.award_prize!
end
3.times.map { |i| "time-#{i}" }
# ["time-0", "time-1", "time-2"]
2.upto(6).map { |i| i }
# [2, 3, 4, 5, 6]
[1, 2, 3, 4, 5, 6].select do |item|
item.odd?
end
#[1, 3, 5]
Blocuri

Blocuri ca argumente
def each_night(&block)
yield :dancing
block.call(:sleeping)
block["acting as a hash"]
end
each_night do |action|
puts "I am #{action}"
end

def inner_state(number)
my_inner_state = if number.odd?
"high"
else
"weird"
end
"I'm feeling #{my_inner_state}"
end
puts inner_state(1)
#I'm feeling high
puts inner_state(2)
#I'm feeling weird
Orice are o valoare

http://mislav.uniqpath.com/poignant-guide/
http://www.ruby-lang.org/en/documentation/
http://www.confreaks.com/

AIESEC 26 Apr 2013

More Related Content

Similar to AIESEC 26 Apr 2013 (20)

Recently uploaded (20)

AIESEC 26 Apr 2013