Ruby Tricks

**에서 매개 변수로 Hash 수신

def my_method(a, *b, **c)
  return a, b, c
end

my_method(1)
# => [1, [], {}]

my_method(1, 2, 3, 4)
# => [1, [2, 3, 4], {}]

my_method(1, 2, 3, 4, a: 1, b: 2)
# => [1, [2, 3, 4], {:a=>1, :b=>2}]

Single Object 및 Arry 작업을 동일하게 처리

stuff = 1
stuff_arr = [1, 2, 3]

[stuff].map { |s| s + 1 }    
# = Array(stuff).map { |s| s + 1 }

[*stuff_arr].map { |s| s + 1 }    
# = stuff_arr.map { |s| s + 1 }    
# = Array(stuff_arr).map { |s| s + 1 }

|||=(@total이 비어 있을 때 실행)

require 'benchmark'

def total(val)
  @total ||= (1..val).to_a.inject(:+)
end

result = Benchmark.realtime do
    total(100000000)
end
puts "1: #{result.round(2)}s"

result = Benchmark.realtime do
    total(100000000)
end
puts "2: #{result.round(2)}s"

자모

('a'..'z').to_a # [*'a'..'z']
# => ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"]

(1..10).to_a # [*1..10]
# => [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

Tap

class User
  attr_accessor :a, :b, :c
end

def my_method
  o = User.new
  o.a = 1
  o.b = 2
  o.c = 3
  o
end

# より読みやすくする
def my_method_readble
  User.new.tap do |o|
    o.a = 1
    o.b = 2
    o.c = 3
  end
end

객체 복사

base = [1, 2, 3]
copy = base
copy.reverse!
p "--- = ---"
p copy
p base
p copy.equal?(base)

base = [1, 2, 3]
copy = base.dup
copy.reverse!
p "--- dup ---"
p copy
p base
p copy.equal?(base)

defxxx (& yy) 블록 매개 변수

yield

def block
  yield
end

block do
  p "This is block!"
end
# "This is block!"

Proc

proc = Proc.new do
  p "This is proc!"
end
proc.call
# "This is proc!"

lambda = lambda {p "This is lambda!"}
# lambda = -> {p "This is lambda!"}
lambda.call
# "This is lambda!"

블록 매개변수

def test1(&block)
    yield
end
test1 do
  p "This is block1!"
end
# "This is block1!"

def test2
    yield
end
test2 do
  p "This is block2!"
end
# "This is block2!"