D-Talk: What's awesome about Ruby 2.x and Rails 4

RUBY 2.X
Thursday, October 10, 13

RUBY
+ berljivost
+ površinska enostavnost
+ polno objektni jezik
+ funkcijsko programiranje
+ metaprogramiranje
+ ekosistem
+ RubyGems
- metaprogramiranje
- hitrost vs. Scala, Java, C
- znanost (SciPy)

(0..10).each do |x|
puts "The number is: #{x}"
end
<?php
for ($x=0; $x<=10; $x++)
{
echo "The number is: $x";
}
?>
for x in range(0, 11):
print 'The number is:
%d' % (x)
Ruby PHP Python

(0..10).each do |x|
end
<?php
for ($x=0; $x<=10; $x++)
{
}
?>
%d' % (x)
Ruby PHP Python
for x in 0..10
puts 'The number is: %d' % [x]
end

(0..10).each do |x|
end
<?php
for ($x=0; $x<=10; $x++)
{
}
?>
%d' % (x)
Ruby PHP Python
for x in 0..10
end
0.upto(10).each { |x|
printf('The number is: %d', x)
}

(0..10).each do |x|
end
<?php
for ($x=0; $x<=10; $x++)
{
}
?>
%d' % (x)
Ruby PHP Python
for x in 0..10
end
}
11.times do |x|
end

(0..10).each do |x|
end
<?php
for ($x=0; $x<=10; $x++)
{
}
?>
%d' % (x)
Ruby PHP Python
for x in 0..10
end
}
11.times do |x|
end
puts (0..10).map{|x| "The number is: #{x}"}

(0..10).each do |x|
end
<?php
for ($x=0; $x<=10; $x++)
{
}
?>
%d' % (x)
Ruby PHP Python
for x in 0..10
end
}
11.times do |x|
end
puts (0..10).map{|x| "The number is: #{x}"}
puts ("The number is Nn" * 11).gsub('N').with_index{|_,i| i}

RUBY 2.0

KEYWORD ARGUMENTI
# Ruby < 2
def run(options = {})
options.reverse_merge!(
opt1: "default"
)
raise ArgumentError unless options.keys.in?([:opt1, :opt2])
options[:opt1]
end
# Ruby 2
def run(opt1: "default", opt2: nil)
opt1
end
run(opt2: "x")
run(opt2: "x", opt3: "y") # ArgumentError
def run(opt1: "default", opt2: nil, **options)
opt1
end
run(opt2: "x", opt3: "y")

MODULE#PREPEND

class Bar
def hello
puts 1
end
end
Bar.new.hello
Bar.ancestors
๏ BasicObject
๏ Kernel
๏ Object
๏ Bar

class Foo
def hello
puts 'hello'
end
end
class Bar < Foo
def hello
puts 1
super
end
end
Bar.new.hello
Bar.ancestors
๏ BasicObject
๏ Kernel
๏ Object
๏ Foo
๏ Bar

module FooBar
def hello
puts 2
super
end
end
class Foo
def hello
puts 'hello'
end
end
class Bar < Foo
include FooBar
def hello
puts 1
super
end
end
Bar.new.hello
Bar.ancestors
๏ BasicObject
๏ Kernel
๏ Object
๏ Foo
๏ FooBar
๏ Bar

module FooBar
def hello
puts 2
super
end
end
class Foo
def hello
puts 'hello'
end
end
class Bar < Foo
include FooBar
def hello
puts 1
super
end
end
Bar.new.hello
Bar.ancestors
๏ BasicObject
๏ Kernel
๏ Object
๏ Foo
๏ FooBar
๏ Bar
1
2
hello

module FooBar
def hello
puts 2
super
end
end
class Foo
def hello
puts 'hello'
end
end
class Bar < Foo
prepend FooBar
def hello
puts 1
super
end
end
Bar.new.hello
Bar.ancestors
๏ BasicObject
๏ Kernel
๏ Object
๏ Foo
๏ Bar
๏ FooBar

module FooBar
def hello
puts 2
super
end
end
class Foo
def hello
puts 'hello'
end
end
class Bar < Foo
prepend FooBar
def hello
puts 1
super
end
end
Bar.new.hello
Bar.ancestors
๏ BasicObject
๏ Kernel
๏ Object
๏ Foo
๏ Bar
๏ FooBar
2
1
hello

LAZY ENUMERATIONS

ENUMERATIONS
[1, 2, 3, 4]
.map { |i| i * 2 } # => [2, 4, 6, 8]
.take(2) # => [2, 4]
.reduce(&:+) # => 6

LAZY
[1, 2, 3, 4]
.lazy # => #<Enumerator::Lazy: [1, 2, 3, 4]>
.map { |i| i * 2 } # => #<Enumerator::Lazy: [1, 2, 3,
4]>:map>
.take(2) # => #<Enumerator::Lazy:
#<Enumerator::Lazy: [1, 2, 3, 4]>:map>:take(2)>
.reduce(&:+) # => 6

LAZY
(1..Float::INFINITY)
.lazy
.map { |i| i * 2 }
.take(2)
.reduce(&:+)

GENERATIONAL GARBAGE
COLLECTOR
If you care about GC, just use JRuby.

GENERATIONAL GARBAGE
COLLECTOR
If you care about GC, just use JRuby.
switch to JRuby

RUBY 2.0: REFINEMENTS
Meh.

RUBY 2.1: REFINEMENTS
module BalkanString
refine String do
def debalkanize
ActiveSupport::Inflector.transliterate(self)
end
end
end
class User < ActiveRecord::Base
using BalkanString
def name
@name.debalkanize if @name
end
end
"test".debalkanize # NoMethodError

RUBY ON RAILS

Django
146,869 LOC
Rails
162,084 LOC
CakePHP
147,738 LOC
Lines of code

100% MODULAREN

Rails
‣lepilo
‣Model
‣View
‣Controller

Rails
‣railties 16,017 LOC
‣activesupport 25,710 LOC
‣Model
‣View
‣Controller

Rails
‣railties
‣activesupport
‣Model
‣View
‣Controller

Rails
‣railties
‣activesupport
‣activemodel 5,694 LOC
‣activerecord 53,435 LOC
‣View
‣Controller

Rails
‣railties
‣activesupport
‣activemodel
‣activerecord
‣View
‣Controller

Rails
‣railties
‣activesupport
‣activemodel
‣activerecord
‣actionview 22,501 LOC
‣Controller

Rails
‣railties
‣activesupport
‣activemodel
‣activerecord
‣actionview
‣Controller

Rails
‣railties
‣activesupport
‣activemodel
‣activerecord
‣actionview
‣actionpack 35,538 LOC

Rails
‣railties
‣activesupport
‣activemodel
‣activerecord
‣actionview
‣actionpack

DEPLOY
Unicorn
Rainbows!

RAILS 4

TURBOLINKS
Video (57:10)
Rails Conf 2013 Patterns of Basecamp's Application
Architecture by David Heinemeier Hansson
http://www.youtube.com/watch?v=yhseQP52yIY

THREAD SAFE
JBoss, 200 threads, OK

DON’T JUSTTRY,TRY!
# Rails 3
[10].try(:count) # => 1
5.try(:count) # NoMethodError
nil.try(:count) # => nil
# Rails 4
5.try(:count) # => nil
5.try!(:count) # NoMethodError
nil.try(:count) #=> nil
nil.try!(:count) #=> nil

ACTIONCONTROLLER::LIVE
class MyController < ActionController::Base
include ActionController::Live
def stream
response.headers['Content-Type'] = 'text/event-stream'
100.times {
response.stream.write "hello worldn"
sleep 1
}
ensure
response.stream.close
end
end
avtomatsko naredi thread

POSTGRESQL
Array

POSTGRESQL ARRAY
class CreateDocuments < ActiveRecord::Migration
def change
create_table :documents do |t|
t.string :title
t.string :tags, array: true, default: []
t.timestamps
end
end
end

POSTGRESQL ARRAY
Document.create(title: "PostgreSQL", tags: ["pg","rails"])
Document.where("'pg' = ANY (tags)")

POSTGRESQL
hstore (Hash/Dictionary)

POSTGRESQL HSTORE
class AddHstoreExtension < ActiveRecord::Migration
def up
execute 'CREATE EXTENSION hstore'
end
def down
execute 'DROP EXTENSION hstore'
end
end
class AddPropertiesToComics < ActiveRecord::Migration
def change
add_column :comics, :properties, :hstore
end
end

POSTGRESQL HSTORE
class Comic < ActiveRecord::Base
end
Comic.create(properties: { issued: 1.year.ago })
Comic.where("properties -> 'issued' > ?", 2.years.ago)

POSTGRESQL HSTORE
class Comic < ActiveRecord::Base
store_accessor :properties, :issued
end
Comic.create(issued: 1.year.ago)
Comic.where("properties -> 'issued' > ?", 2.years.ago)
Ali sploh rabiš hstore v tem primeru?

ACTIVERECORD
In Rails 4

SCOPES
# Rails 3
scope :newest, where("created_at > ?", 1.week.ago)
# Rails 4
scope :newest, -> { where("created_at > ?", 1.week.ago) }
end

WHERE.NOT
# Rails 3
User.where('role != ?', 'admin')
User.where('nickname IS NOT NULL')
# Rails 4
User.where.not(role: 'admin')
User.where.not(nickname: nil)

MIGRACIJE PREJ
class ChangeProductsPrice < ActiveRecord::Migration
def up
change_table :products do |t|
t.change :price, :string
end
end
def down
t.change :price, :integer
end
end
end

MIGRACIJE
class ChangeProductsPrice < ActiveRecord::Migration
def change
reversible do |dir|
dir.up { t.change :price, :string }
dir.down { t.change :price, :integer }
end
end
end
end

NONE RELATION
scope :with_role, ->(role) {
if User.role_valid? role
where(role: role)
else
none
end
}
end
User.with_role(params[:role]).where.not(nick: nil)

STRONG PARAMETERS

PROBLEM
• User
• name
• is_admin

RAILS 3
attr_accessible :name
end
# controller
user.update_attributes(params[:user])
# admin
user.update_attributes(is_admin: true) # :-(
user.is_admin = true
user.save

RAILS 3
end
# controller
v čem je v resnici problem?

RAILS 3
end
# controller
user.update_attributes(is_admin: true) # :-(
non-sanitized
user input

STRONG PARAMETERS
end
# controller
def user_params
params.require(:user).permit(:name)
end
user.update_attributes(user_params)
# error: Unpermitted parameters
user.update_attributes(is_admin: true) # OK :-)

CACHING
• avtomatski expire pri spremembi modela
• avtomatski expire pri spremembi viewa
• russian doll (nested) caching
• Rails Conf 2013 Patterns of Basecamp's Application
Architecture by David Heinemeier Hansson
• http://www.youtube.com/watch?v=yhseQP52yIY

ACTIVESUPPORT::CONCERN
module Commentable
extend ActiveSupport::Concern
included do
has_many :comments
end
def has_comments?
!comments.empty?
end
module ClassMethods
def comments_count
joins(:comments)
.references(:comments)
.pluck("COUNT(comments.id)")
end
end
end
class Post < ActiveRecord::Base
include Commentable
end
User.posts.comment_count
Post.first.comments
Post.first.has_comments?
Rails 4 ima direktorij za concerne.
Whatever.

THE END

D-Talk: What's awesome about Ruby 2.x and Rails 4

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