Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
Ruby: Dicas & Truques
Search
Nando Vieira
July 07, 2012
Technology
20
1.3k
Ruby: Dicas & Truques
Nando Vieira
July 07, 2012
Tweet
Share
More Decks by Nando Vieira
See All by Nando Vieira
Permanecendo Relevante
fnando
9
1.5k
O que mudou no Rails 5
fnando
3
550
Porque usar PostgreSQL (Se você ainda não o faz)
fnando
25
2.9k
Criando aplicações web mais seguras
fnando
4
660
Criando aplicações mais fáceis de manter com Ruby on Rails
fnando
35
2.1k
Conhecendo Variants do Rails 4.1
fnando
11
560
JavaScript Funcional
fnando
36
1.8k
Segurança em Aplicações Web
fnando
31
3k
Segurança no Rails
fnando
20
940
Other Decks in Technology
See All in Technology
機械学習を扱うプラットフォーム開発と運用事例
lycorptech_jp
PRO
0
250
未経験者・初心者に贈る!40分でわかるAndroidアプリ開発の今と大事なポイント
operando
5
630
react-callを使ってダイヤログをいろんなとこで再利用しよう!
shinaps
1
240
なぜスクラムはこうなったのか?歴史が教えてくれたこと/Shall we explore the roots of Scrum
sanogemaru
5
1.6k
研究開発と製品開発、両利きのロボティクス
youtalk
1
530
ブロックテーマ時代における、テーマの CSS について考える Toro_Unit / 2025.09.13 @ Shinshu WordPress Meetup
torounit
0
130
20250910_障害注入から効率的復旧へ_カオスエンジニアリング_生成AIで考えるAWS障害対応.pdf
sh_fk2
3
260
AI時代を生き抜くエンジニアキャリアの築き方 (AI-Native 時代、エンジニアという道は 「最大の挑戦の場」となる) / Building an Engineering Career to Thrive in the Age of AI (In the AI-Native Era, the Path of Engineering Becomes the Ultimate Arena of Challenge)
jeongjaesoon
0
150
共有と分離 - Compose Multiplatform "本番導入" の設計指針
error96num
2
570
Snowflake Intelligenceにはこうやって立ち向かう!クラシルが考えるAI Readyなデータ基盤と活用のためのDataOps
gappy50
0
240
LLMを搭載したプロダクトの品質保証の模索と学び
qa
0
1.1k
【実演版】カンファレンス登壇者・スタッフにこそ知ってほしいマイクの使い方 / 大吉祥寺.pm 2025
arthur1
1
850
Featured
See All Featured
Performance Is Good for Brains [We Love Speed 2024]
tammyeverts
12
1.1k
The Invisible Side of Design
smashingmag
301
51k
Code Reviewing Like a Champion
maltzj
525
40k
How to train your dragon (web standard)
notwaldorf
96
6.2k
4 Signs Your Business is Dying
shpigford
184
22k
How to Think Like a Performance Engineer
csswizardry
26
1.9k
Understanding Cognitive Biases in Performance Measurement
bluesmoon
29
1.9k
Code Review Best Practice
trishagee
70
19k
Navigating Team Friction
lara
189
15k
[RailsConf 2023] Rails as a piece of cake
palkan
57
5.8k
Into the Great Unknown - MozCon
thekraken
40
2k
For a Future-Friendly Web
brad_frost
180
9.9k
Transcript
DICAS & TRUQUES RUBY Nando Vieira hellobits.com
@fnando
None
None
None
DICAS E TRUQUES CURIOSOS QUE PODEM SER ÚTEIS (OU NÃO)
NO DIA-A-DIA.
None
No Ruby, tudo é objeto (ou quase tudo).
Classes, módulos, números, strings, arrays, intervalos, símbolos, métodos, blocos, procs,
nil, booleanos, hashes, expressões regulares.
O Ruby possui classes abertas que podem ser modi cadas
a qualquer momento.
O Ruby é extremamente exível.
O Ruby é muito mais difícil do que as pessoas
assumem.
DUCK TYPING, PROTOCOLOS E CONTRATOS
O Duck Typing permite estabelecer interfaces com um contrato informal.
class SimpleLogger def initialize(storage = []) unless storage.is_a?(Array) raise "you
need to pass an array" end @storage = storage end def log(message) @storage << message end end
def initialize(storage = []) unless storage.is_a?(Array) raise "you need to
pass an array" end @storage = storage end
def log(message) @storage << message end
@storage.<<(value)
File#<< String#<< Array#<< CSV#<< Set#<< IO#<< StringIO#<< Queue#<<
class SimpleLogger def initialize(storage = []) @storage = storage end
def log(message) @storage << message end end
logger = SimpleLogger.new(nil) logger.log("Hello") #=> NoMethodError: undefined #=> method `<<'
for nil:NilClass
O Ruby leva o Duck Typing por toda a linguagem,
usando-o como protocolo de coersão.
#to_a #to_ary #to_d #to_f #to_i #to_proc #to_s
#to_proc
people = Person.all names = people.map do |person| person.name end
people = Person.all names = people.map(&:name)
&Na assinatura do método, converte bloco em Proc.
&Na chamada do método, converte Proc em bloco.
method(&object)
object.to_proc
people.map(&:name)
:name.to_proc #=> #<Proc:0x871cd04>
:name .to_proc .call(people.first)
class Symbol def to_proc proc do |target| target.public_send(self) end end
end
PROCS & LAMBDAS
sum_proc = proc do |n1, n2| n1 + n2 end
sum_lambda = lambda do |n1, n2| n1 + n2 end
sum_proc.class #=> Proc sum_lambda.class #=> Proc
sum_proc.lambda? #=> false sum_lambda.lambda? #=> true
sum_proc.parameters #=> [[:opt, :n1], [:opt, :n2]] sum_lambda.parameters #=> [[:req, :n1],
[:req, :n2]]
Os parâmetros de um lambda são obrigatórios por padrão.
sum_proc.call #=> NoMethodError: undefined #=> method `+' for nil:NilClass sum_lambda.call
#=> ArgumentError: wrong number #=> of arguments (0 for 2)
def proc_return proc { return "returning from proc" }.call "proc
has finished" end puts proc_return #=> returning from proc
O retorno da proc, na verdade, faz com que o
método pare de executar.
def lambda_return lambda { return "lambda: exiting method" }.call "lambda
has finished" end puts lambda_return #=> lambda has finished
O retorno do lambda é auto- contido e não afeta
o método.
O retorno de procs pode, inclusive, lançar exceções.
lambda { return "hello" }.call #=> hello proc { return
"hello" }.call #=> LocalJumpError: unexpected return
proc { next "hello" this_wont_be_executed }.call
CALLABLE OBJECTS
hello = proc do |name| puts "hello, #{name}!" end
hello.call("John")
hello["John"]
hello.("John")
hello === "John"
object = 9 multiple_of_3 = proc do |n| n.modulo(3).zero? end
case object when multiple_of_3 "is multiple of 3" when Array
"is a array" when /@/ "contains at-sign" else "couldn't understand" end
Proc#=== Regexp#=== Module#===
Array === [] #=> true multiple_of_3 === 9 #=> true
/@/ === "
[email protected]
" #=> true
Object#method Module#instance_method
Métodos não são objetos de primeira classe.
Estendendo métodos sem ter que criar uma nova classe.
class Hellobits def cool # do something end end
class Hellobits alias_method :original_cool, :cool def cool # do something
before original_cool # do something after end end
class Hellobits cool_method = instance_method(:cool) define_method :cool do # do
something before cool_method.bind(self).call # do something after end end
SPLATTING
*args
class Module def attr_dsl(*args) args.each do |arg| # do something
end end end
class Settings names = %w[path size locale] attr_dsl *names end
def coords(*) # do something -23.598737, -46.674685 end latitude, longitude
= coords
a, b, c, d = [1, 2, 3, 4]
a, b, c, d = 1, 2, 3, 4
a, b, *c = 1, 2, 3, 4 #=> a=1,
b=2, c=[3,4]
a, *b, c = 1, 2, 3, 4 #=> a=1,
b=[2,3], c=4
numbers = [1, 2, 3] more_numbers = [*numbers, 4, 5,
6] #=> [1, 2, 3, 4, 5, 6]
(1..10).to_a.sample [*1..10].sample
date = "2012-07-10" regex = /(\d+)-(\d+)-(\d+)/ _, year, month, day
= *date.match(regex)
class Sample def to_a [1, 2, 3] end end a,
b, c = *Sample.new
MAIS SOBRE ATRIBUIÇÕES
path = nil if !path path = "/some/default/path" end
path = nil path = "/some/path" unless path
path = nil path ||= "/some/path"
variable || variable = expr
html = nil if html html << "<p>Hello</p>" end
html = nil html << "<p>Hello</p>" if html
html = nil html &&= html << "<p>Hello</p>"
variable && variable = expr
DE ONDE VEM ESSE MÉTODO
user = User.new user.methods #=> [:name, :age, ...]
user.method(:name)
Method#arity Method#name Method#owner Method#parameters Method#source_location
user.method(:name) .source_location #=> ["/tmp/user.rb", 2]
EXPRESSÕES REGULARES
person = "John <
[email protected]
>" regex = /(.*?) <(.*?)>/ _, name,
email = *person.match(regex)
person[/(.*?) <(.*?)>/, 1] person[/(.*?) <(.*?)>/, 2]
person .match(/(?<name>.*?) <(?<email>.*?)>/)
match.names #=> ["name", "email"] match.captures #=> ["John Doe", "
[email protected]
"] match[:name]
#=> "John Doe" match[:email] #=> "
[email protected]
"
ENUMERATORS
names.each(&block) names.each_with_index(&block)
names.each_with_index do |name, index| puts "#{index + 10}. #{name}" end
names .each .with_index(10) do |name, index| puts "#{index}. #{name}" end
names .sort .uniq .each .with_index(10, &block)
HASHES & ENUMERATORS
hash.each do |key, value| # do something end
hash .each .with_index(10) do |pair, index| name, value = pair
# do something end
hash .each .with_index(10) do |(name, value), index| # do something
end
SYMBOLS
:name
:"full name"
:"hello #{name}"
E PARA FINALIZAR...
O Ruby possui uma série de truques que podem ajudar
bastante.
Mais do que saber usar, você precisa saber quando usar.
Sintaxes exotéricas serão mais difíceis de entender.
Conheça Ruby. Todo o resto vem de graça.
OBRIGADO!