Ruby 2.0 / Rails 4.0, A selection of new features.

Ruby 2.0 / Rails 4.0A selection of new features

Evan DornFounder, Logical Reality Design

http://lrdesign.comevan@lrdesign.com

@idahoev

Friday, August 9, 13

RUBY 2.0:A FEW COOL BITS

hash representation, like to_a or to_s or

to_sym.

Implemented on:•ENV•NilClass•Struct•Your classes!•ActiveRecord::Base (hopefully soon...)

#bsearch

Fast binary search!

•Array•Range

2.0.0p195 :003 > arr = [1, 3, 5, 7, 10, 11, 12, 14, 16, 18, 19] => [1, 3, 5, 7, 10, 11, 12, 14, 16, 18, 19]

#bsearch

2.0.0p195 :003 > arr = [1, 3, 5, 7, 10, 11, 12, 14, 16, 18, 19] => [1, 3, 5, 7, 10, 11, 12, 14, 16, 18, 19] 2.0.0p195 :004 > n = 0 => 0

#bsearch

2.0.0p195 :003 > arr = [1, 3, 5, 7, 10, 11, 12, 14, 16, 18, 19] => [1, 3, 5, 7, 10, 11, 12, 14, 16, 18, 19] 2.0.0p195 :004 > n = 0 => 0 2.0.0p195 :005 > arr.find{ |elem| p (n = n+1); elem == 11 }

#bsearch

2.0.0p195 :003 > arr = [1, 3, 5, 7, 10, 11, 12, 14, 16, 18, 19] => [1, 3, 5, 7, 10, 11, 12, 14, 16, 18, 19] 2.0.0p195 :004 > n = 0 => 0 2.0.0p195 :005 > arr.find{ |elem| p (n = n+1); elem == 11 }1234567891011 => 11

#bsearch

2.0.0p195 :003 > arr.bsearch{ |elem| p (n = n+1); elem == 11 }

#bsearch

2.0.0p195 :003 > arr.bsearch{ |elem| p (n = n+1); elem == 11 }123 => 11

#bsearch

WARNING!

Undefined behavior if your Array is not

sorted!

REFINEMENTS

•Hopefully improves the monkeypatch madness

•How many Core or StdLib classes does Rails extend?

•String

•Integer•Hash• Range• Array

•Regexp

•Proc•Date

•File

•Marshal

•Logger•NameError

•Numeric

•BigDecimal

•LoadError •Time

REFINEMENTS

•Hopefully improves the monkeypatch madness

•How many Core or StdLib classes does Rails extend?

•String

•Integer•Hash• Range• Array

•Regexp

•Proc•Date

•File

•Marshal

•Logger•NameError

•Numeric

•BigDecimal

•LoadError •Time

•Module

•Class•Object

REFINEMENTS

•What’s wrong with all this?

•“core” becomes a bit meaningless

•All loaded code sees these mutant core classes

•Harder to write gems that both with and without Rails

NON-REFINEMENTSmodule MyExtensions def do_stuff endend

class String include MyExtensionsend

# all loaded code sees String#do_stuff

# String.new.instance_methods changes...

# String.new.respond_to changes...

REFINEMENTSmodule MyExtensions refine String do def do_stuff p “awesome!” end endend

String.new.do_stuff # undefined method “do_stuff”

using MyExtensions

String.new.do_stuff

=> “awesome!”

using MyExtensions

String.new.do_stuff

=> “awesome!”

using MyExtensions

String.new.do_stuff

=> “awesome!”

using MyExtensions

String.new.do_stuff

=> “awesome!”

using MyExtensions

String.new.do_stuff

=> “awesome!”

using MyExtensions

String.new.do_stuff

=> “awesome!”

using MyExtensions

String.new.do_stuff

=> “awesome!”

KEYWORD ARGUMENTS

•my_method(options = {}) has problems

•assigning defaults with merge({...}) is fugly

•options[:mispeled_arg] silently returns nil!

•options = {} allocates a new hash on every call

KEYWORD ARGUMENTSdef my_method(arg1: ‘foo’, arg2: 123) p arg1 p arg2end

my_method“foo” 123=> 123

KEYWORD ARGUMENTSdef my_method(arg1: ‘foo’, arg2: 123) p arg1 p arg2end

my_method“foo” 123=> 123

WARNING!

THOSE ARGS ARE NOT A HASH!

KEYWORD ARGUMENTSdef my_method(:arg1 => 'foo', :arg2 => 123) # doesn’t workend

SyntaxError: (irb):27: syntax error, unexpected tSYMBEG, expecting ')'def my_method(:arg1 => 'foo', :arg2 => 123) ^

KEYWORD ARGUMENTSdef my_method(:arg1 => 'foo', :arg2 => 123) # doesn’t workend

SyntaxError: (irb):27: syntax error, unexpected tSYMBEG, expecting ')'def my_method(:arg1 => 'foo', :arg2 => 123) ^

MODULE#PREPEND •I didn’t have time to write this slide!

•But the feature is awesome, I promise!

SAD PUPPY

RAILS 4.0!

MASS-ASSIGNMENTPROTECTION

•No more “attr_accessible” in the Model

•It’s a controller concern

•... because it’s often different in different controllers

•(admin controllers, etc.)

STRONG PARAMSclass UsersController < ApplicationController def update user = User.find(params[:id]) if user.update_attributes(user_params) # see below redirect_to home_path else render :edit end end private # Require that :user be a key in the params Hash, # and only accept :first, :last, and :email attributes def user_params params.require(:user).permit(:first, :last, :email) endend

STRONG PARAMS

•Params hashes get some new methods

•e.g. params.permitted?

•params hash will contain only the permitted keys

•No deep permits: if the Hash contains a Hash, you must permit nested keys specifically

FRAGMENT CACHING

•Caching HTML fragments can be a huge speedup

•Expiring fragments correctly is a bitch

•... especially if they’re nested

•... and slow if you have a lot of cache keys

OLD BUSTED CACHING%h2 To-do List- cache “todo_for_#{current_user.id}” do %table - @todo_items.each do |item| - cache “todo_item_#{item.id}” do %tr %td= item.name %td= item.importance

RUSSIAN DOLL CACHING

•Important changes:

•cache(key) do ...end takes an Array for the key

•key generation concatenates the array elements

•after calling #cache_key on any members that respond to that method

NEW HOTNESS CACHING%h2 To-do List- cache [ :todo_list, current_user, @todo_list ] do %table - @todo_list.items.each do |item| - cache [ :todo_item, item ] do %tr %td= item.name %td= item.importance

NEW HOTNESS CACHING%h2 To-do List- cache [ :todo_list, current_user, todo_list ] do %table - @todo_list.items.each do |item| - cache [ :todo_item, item ] do %tr %td= item.name %td= item.importance

class TodoItem < ActiveRecord::Base def cache_key “#{self.id}-#{self.updated_at.to_s(:number)}” endend

class TodoList # A presenter attr_accessor :items # array of items attr_accessor :user # User object def cache_key “#{user.id}-#{items.newest.updated_at.to_s(:number)“ end end

class TodoItem < ActiveRecord::Base def cache_key “#{self.id}-#{self.updated_at.to_s(:number)}” endend

class TodoList # A presenter attr_accessor :items # array of items attr_accessor :user # User object def cache_key “#{user.id}-#{items.newest.updated_at.to_s(:number)“ end end

class TodoItem < ActiveRecord:: Base def cache_key “#{self.id}-#{self.updated_at.to_s(:number)}” endend

class TodoList # A Presenter attr_accessor :items # array of items attr_accessor :user # User object def cache_key “#{user.id}-#{items.newest.updated_at.to_s(:number)“ end end

class TodoItem def cache_key “#{self.id}-#{self.updated_at.to_s(:number)}” endend

class TodoList attr_accessor :items # array of items attr_accessor :user # User object def cache_key “#{items.newest.updated_at.to_s(:number)“ end end

class TodoItem def cache_key “#{self.id}-#{self.updated_at.to_s(:number)}” endend

class TodoList attr_accessor :items # array of items attr_accessor :user # User object def cache_key “#{items.newest.updated_at.to_s(:number)“ end end

class User < ActiveRecord::Base def cache_key “#{self.id}-#{self.updated_at.to_s(:number)}” end end

NEW HOTNESS CACHING%h2 To-do List- cache [ :todo_list, current_user, todo_list ] do -# “todo_list/1234-201308081234/201308081146” %table - @todo_list.items.each do |item| - cache [ :todo_item, item ] do %tr %td= item.name %td= item.importance

NEW HOTNESS CACHING%h2 To-do List- cache [ :todo_list, current_user, todo_list ] do -# “todo_list/1234-201308081234/201308081146” %table - @todo_list.items.each do |item| - cache [ :todo_item, item ] do -# “todo_item/5316-201306071156” %tr %td= item.name %td= item.importance

RUSSIAN DOLL CACHING

•With clever key construction:

•Every model update causes a cache miss

•... Never have to invalidate fragments!

•Any decent memory store will expire unused keys for you

PSST... A SECRET:You can do this in Rails 3, too.

Just write your own smart cache key helpers.

PATCH•PUT is no longer the default HTTP method for #update

actions.

•(Because PUT is defined to be whole-object, never partial, and should avoid side-effects.)

•Use PATCH instead

•Affects: config/routes.rb, tests, etc.

ACTIVEMODEL::MODEL

•Turns any object into a proper model

•For use with form_for(), etc.

•attr_accessors become AM-style attributes

•Adds name introspection, conversion, I18n support, validations, etc...

ACTIVEMODEL::MODEL

Helps to break the tendency to equate “resource” with “ActiveRecord Model.”

ACTIVEMODEL::MODELclass UserFormModel include ActiveModel::Model

def new(user) @user = user @settings = user.settings end

attr_accessor :name, :admin

def persisted? @user.persisted? end

def persist! @user.name = name @user.save! @settings.admin = admin @settings.save! endend

def persist! @user.name = name @user.save! @settings.admin = admin @settings.save! end

def persisted? # default false if not overridden! @user.persisted? end

ACTIVEMODEL::MODEL# /app/views/users/_form

= form_for(@user_form_model) = f.input(:name) = f.check_box(:admin) = f.submit!

ACTIVEMODEL::MODEL# /app/views/users/_form

= form_for(@user_form_model) = f.input(:name) = f.check_box(:admin) = f.submit!

AVOIDING FULL PAGE LOADS

CHECK OUT “TURBOLINKS”

OR JUST USE:•AngularJS•EmberJS•Backbone•etc...

‘cause that’s probably the

right tool,really.

STREAMING SUPPORT!

ACTIONCONTROLLER::LIVEclass MyController < ActionController::Base include ActionController::Live

def stream response.headers['Content-Type'] = 'text/event-stream' 100.times { response.stream.write "hello world\n" sleep 1 } ensure response.stream.close end

ACTIONCONTROLLER::LIVE

•Don’t try to change headers after calling response.stream.write...

•Don’t forget to close...

•Stream actions automatically happen in a separate thread.

•(So make sure it’s thread-safe!)

ANY TIME LEFT? (IF SO, I’LL DO

MODULE#PREPEND ON A WHITEBOARD OR SOMETHING.)

Thanks!

Evan DornFounder, Logical Reality Design

http://lrdesign.comevan@lrdesign.com

@idahoev

Ruby 2.0 / Rails 4.0, A selection of new features.

Technology

Transcript of Ruby 2.0 / Rails 4.0, A selection of new features.

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