Apresentação

• Ciência da Computação

• UFLA - Comp 2007/1

• Fila de carona gigante

• Elefantinho lotado

• Brejão

Apresentação

• Java Developer

• Ruby/Rails Developer

• JavaScript Developer

• twitter | github | fb | gtalk : jlucasps
• linkedin.com/in/jlucasps

Histórico

Histórico

Feb. 23 1993

"... object-oriented scripting language. I knew Perl (Perl4, not Perl5), but I didn't like it really, because it had smell of toy language (it still has)."

Histórico

"I knew Python then. But I didn't like it, because I didn't think it was a true object-oriented language."

Histórico

"So, I decided to make it." Matz

"It took several months to make the interpreter run. [...] I posted Ruby 0.95 to the Japanese domestic newsgroups in Dec. 1995. " Matz

Everything is a object

4.even?                     # => true
3.upto(8).to_a              # => [3, 4, 5, 6, 7, 8]
"A string literal".length()   # => 16
						

Everything is a object

[].methods
=> [:inspect, :to_s, :to_a, :to_ary, :frozen?, :==, :eql?, :hash, :[],
:[]=, :at, :fetch, :first, :last, :concat, :<<, :push, :pop, :shift,
:unshift, :insert, :each, :each_index, :reverse_each, :length, :size,
:empty?, :find_index, .... ]
						

Everything is a object

10.methods
 => [:to_s, :inspect, :-@, :+, :-, :*, :/, :div, :%, :modulo, :divmod, :fdiv,
 :**, :abs, :magnitude, :==, :===, :<=>, :>, :>=, :<, :<=, :~, :&, :|, :^,
 :[], :<<, :>>, :to_f, :size, :zero?, :odd?, :even?, :succ, :integer?,
 :upto, :downto, :times, :next, :pred, :chr, :ord, :to_i, :to_int, :floor,
 :ceil, :truncate, :round, :gcd, :lcm, :gcdlcm, :numerator, :denominator,
 :to_r, :rationalize, :singleton_method_added, :coerce, :i, :+@, :eql?, ... ]
						

Everything is a object

true.class
 => TrueClass
1.4.class
 => Float

'1+3i'.to_c.class
 => Complex
 '1+3i'.to_c.class.ancestors
 => [Complex, Numeric, Comparable, Object, Kernel, BasicObject]

'1+3i'.to_c.class.class
 => Class

Everything is a object

Ruby code conventions

class InfoCompMagazine
  # ...
end

def number_of_pages
  # some code here ...
end
def web_magazine?
  # more code ...
end
def change_folder!
  # code code code ...
end

Ruby code conventions

Ruby classes

class Book
  def initialize(title)
    @title = title
  end

  def title
    @title
  end
end

Ruby classes

book = Book.new "Eloquent Ruby"
puts book.title # "Eloquent Ruby"
puts book.send :title # "Eloquent Ruby"
 						

book = Book.new( "Eloquent Ruby" )
puts book.title() # "Eloquent Ruby"
puts book.send( :title ) # "Eloquent Ruby"
 						

Ruby classes

// Java class
public class Person {

  private int age;

  public int getAge() {
       return this.age
  }
  public void setAge(int age) {
       this.age = age;
  }
}

# Ruby class
class Person
  attr_accessor :age
end

Variáveis

class Magazine
  MAX_PAGES = 30 # contants
end

class Magazine
  def initialize
    @max_pages = 30 # instance variable
  end
end

class Magazine
  @@max_pages = 30 # class variable
  def initialize
    # ...
  end
end

Classes abertas

class Fixnum
  def +( num )
    self - num
  end
end
puts 2 + 3

=> -1

Ruby e "Modo Poesia"

Armando Fox, University of California, Berkeley

def print_user_info( info )
  puts "Info about user:"
  info.each_pair { |key, value| puts "#{key}: #{value}" }
end
print_user_info( { name: "Joao lucas", email: "jlucasps@gmail.com" } )
# Info about user:
# name: Joao lucas
# email: jlucasps@gmail.com
 						

print_user_info( name: "Joao lucas", email: "jlucasps@gmail.com" )

print_user_info name: "Joao lucas", email: "jlucasps@gmail.com"
 						

Ruby e "Modo Poesia"

Armando Fox, University of California, Berkeley

user.age.should(be() >= 18)
user.age.should be >= 18
 						

if !logged_in?() # unless logged_in?()
  ( redirect_to( login_page() ) ) and return()
end
# ...
( redirect_to( login_page() ) and return() ) unless logged_in?()
# ...
( redirect_to login_page and return ) unless logged_in?
 						

Metaprogramming

class Car

end
car = Car.new
car.run # undefined method `run' for #<Car:0x00000001c8d970> (NoMethodError)

# singleton method
def car.run
  puts "wooowww Car running now!"
end
car.run # wooowww Car running now!

car2 = Car.new
car2.run # undefined method `run' for #<Car:0x00000002292898> (NoMethodError)

Metaprogramming

class User
  attr_accessor :name, :age, :city
  def initialize name, age, city
    @name, @age, @city = name, age, city
  end
end
user = User.new "João Lucas", 25, "BH"
puts "#{user.name}, #{user.age()} years old, from #{user.city}."
puts user.move( "BH", "POA" )

# Joao Lucas, 25 years old, from BH.
# undefined method `move' for #<User:0x994cee8 @name="João Lucas", @age=25, @city="BH"> (NoMethodError)

Metaprogramming

class User
  def method_missing( method, *args, &block)
    puts "ops.. you can not call #{method}(..) with params #{args.to_a} right now."
    puts "Try again next week! :-D"
  end
end
puts user.move( "BH", "POA" )

# Joao Lucas, 25 years old, from BH.
# ops.. you can not call move(..) with params ["BH", "POA"] right now.
# Try again next week! :-D

Metaprogramming

class User
  MOVE_OPTIONS = [:trip, :travel, :move, :go]

  MOVE_OPTIONS.each do | name |
    define_method( name ) do | *args |
      puts "Method #{name}(..) called with args #{args.inspect}"
    end
  end
end
puts user.move( "BH", "POA" )

# Method move(..) called with args ["BH", "POA"]

High traffic sites built in Ruby on Rails

quora.com/What-are-some-highly-trafficked-sites-built-in-Ruby-on-Rails

• Twitter
• SlideShare
• hulu.com
• White Pages
• Shopify
• Yellow Pages

• Github
• Groupon
• JustinTV
• Basecamp
• BrowserStack
• Ask.fm

• 8tracks
• Soundcloud
• Urban Dictionary
• Scribd
• Yammer
• UserVoice

Learn Ruby

Learn Ruby