Transcript
“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 endend
module Armour def shiny_armour? true endend
knight = Knight.newknight.shiny_armour?# falseknight.extend Armourknight.shiny_armour?# true
Orice este un obiect !!!
Intrebari ?
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
Intrebari ?
http://mislav.uniqpath.com/poignant-guide/
http://www.ruby-lang.org/en/documentation/
http://www.confreaks.com/
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