Código Saudável => Programador Feliz - Rs on Rails 2010

Código Saudável =>
Programador Feliz

Arquitetura
Modelos

Produção

Model View

Controller

Model

Controller

View View View View View

class ArticlesController < ActionController::Base
def index
if params[:user_id].blank?
@articles = Article.all
else
@articles = current_user.articles
end
end
end

Model

Deslogado Logado

Controller Controller

View View View View View View

class ArticlesController < ActionController::Base
def index
@articles = Article.all
end
end

class Users::ArticlesController < ActionContro...
def index
@articles = current_user.articles.all
end
end

class UsersControllers < ApplicationController
def index
@users = User.all
end
end

class Admin::UsersControllers < ApplicationCont...
def index
@users = User.all
end
end

module UsersIndex
def index
@users = User.all
end
end

class UsersController < ApplicationController
include UsersIndex
end

class Admin::UsersControllers < ApplicationController
include UsersIndex
end

Acoplamento
X
Repetição de
código

“Every piece of knowledge
must have a single,
unambiguous, authoritative
representation within a
system.”
Pragmatic Programmer

Repeat code

=
Repeat Logic

Não economizar no
número de controllers

Cada Controller é uma
lógica diferente

DRY não é economizar
código, mas manter as
lógicas em um lugar só

Muitas
Difícil Manter
Responsabilidades

Difícil
Baixa Coesão
Compreender

Sintoma #1
Muita
Responsabilidade

class Account < ActiveRecord::Base
validates_numericality_of :amount
validates_inclusion_of :currency, :in => %w( us_dollar euro (...))

def convert_to_us_dollar
if currency == :us_dollar
currency
elsif currency == :euro
currency * ConversionRate.rate(:dollar,:euro)
(...)
end
end

def convert_to_euro
if currency == :euro
currency
elsif currency == :dollar
currency * ConversionRate.rate(:euro,:dollar)
(...)
end
end
end

class Money
def initialize(amount, currency)
@amount, @currency = amount, currency
end

def convert_to_us_dollar
if currency == :us_dollar
@currency
elsif currency == :euro
@currency * ConversionRate.rate(:dollar,:euro)
(...)
end
end

def convert_to_euro
if currency == :euro
@currency
elsif @currency == :dollar
@currency * ConversionRate.rate(:euro,:dollar)
(...)
end
end

class Account < ActiveRecord::Base
validates_numericality_of :amount
validates_inclusion_of :currency, :in => %w( us_dollar
euro (...))

composed_of :balance, :class_name =>
Money, :mapping => %w( amount currency)
end

Mais fácil de manter Responsabilidades
(e reutilizar!) divididas

Mais simples de
APIs menores
compreender

class Post < ActiveRecord::Base
# (...)
default_scope where(trashed: false)
scope :trashed, where(trashed: true)

def trash
update_attribute :trashed, true
end
end

class Comment < ActiveRecord::Base
# (...)

def trash
end
end

module Trashable
extend ActiveSupport::Concern

included do
end

def trash
end
end

class Post < ActiveRecord::Base
include Trashable
end

class Comment < ActiveRecord::Base
include Trashable
end

Sintoma #3
“Super Abstração”
do Banco de Dados

post.comments.size
post.comments.cou
nt
post.comments.length

SQL (0.3ms) SELECT COUNT(*) FROM `comments`
WHERE (`comments`.post_id = 1)

Comment Load (0.4ms) SELECT `comments`.* FROM
`comments` WHERE (`comments`.post_id = 1)

# File activerecord/lib/active_record/relation.rb, line 84
def size
loaded? ? @records.length : count
end

Active Record é bom!
Mas que de olho no
banco!

<% comments.each do |comment| %>
<% if comment.post %>
(...)
<% end %>
<% end %>

Comment Load (0.6ms) SELECT `comments`.* FROM `comments`
Post Load (0.4ms) SELECT `posts`.* FROM `posts` WHERE `posts`.`id` =
1 LIMIT 1
2 LIMIT 1
(...)
99 LIMIT 1
Post Load (0.2ms) SELECT `posts`.* FROM `posts` WHERE `posts`.`id`
= 100 LIMIT 1

<% comments.each do |comment|
%>
<% if comment.post_id %>
(...)
<% end %>
<% end %>

`comments`

@comments = Comment.all(
:include => :post)

`comments`
Post Load (46.4ms) SELECT `posts`.* FROM `posts` WHERE
(`posts`.`id` IN (1,2,(...),100))

Extrair funcionalidades dos modelos: Composed of

Eliminar duplicação de lógicas Concern

Ficar de olho nas Queries Query Reviewer

Analytics

Exception noti er

Performance logger

Monitoramento de Servidor

Nota A no YSlow

Deploy automatizado

Backup

Solução Open Source
Solução via “serviço”

git pull
touch tmp/restart.txt

git pull
jammit

rake db:backup
git pull
rake db:migrate
jammit

ps aux | ... | kill ...
rake db:backup
git pull
(...) rake resque:(...)
rake db:migrate
jammit

ps aux | ... | kill ...
rake db:backup
git pull
(...) rake resque:(...)
rake sphinx:rebuild
rake db:migrate
jammit

Mais de uma máquina ?
Rollback ?
Múltiplos Ambientes

Crie um padrão de qualidade !

Invista tempo (ou $$ ) em melhorias !

Faça e cumpra um checklist

Código bem feito +
Aplicação bem monitorada
=> Programador Mais Feliz!

Make it work (and write
tests to ensure that)
Make it awesome
(with tests you know that it still works)

if you need, make it fast

Rodrigo Flores blog.plataformatec.com @rlmﬂores

Perguntas?

ID blog twitter

Rodrigo Flores blog.plataformatec.com @rlmﬂores

Perguntas?

Créditos das Imagens

Lego triste
http://www. ickr.com/photos/kalexanderson/
5421517469/
Parquímetro de Portugal
http://weblog.savanne.be/423-youre-doing-it-wrong

“Cafeteira”
http://therei xedit.failblog.org
Airplane
http://www. ickr.com/photos/irish yguy/2426063460/

Código Saudável => Programador Feliz - Rs on Rails 2010

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