TIS = Today I shared

001_mechanisms_to_declare_behavior.rb

#
# Métodos globais
#
def calc_sum(a, b)
  a + b
end

puts calc_sum(1, 3)

# Classes com métodos estáticos
class Calc
  def self.sum(a, b)
    a + b
  end
end

puts Calc.sum(1, 1)

#
# Classes com métodos de instância
#
class Calc
  def sum(a, b)
    a + b
  end
end

calc = Calc.new
puts calc.sum(1, 1)

#
# Funções (Ruby lambdas)
#
calc_sum = -> (a, b) { a + b }
puts calc_sum.call(1, 2)
puts calc_sum.(1, 2)
puts calc_sum[1, 2]

=begin
// Equivalência da função acima em Ruby escrita em JS;

// ES5
calcSum = function(a, b) {
  return a + b;
}

// ES6
calcSum = (a, b) => a + b;
=end

002_memoization.rb

require 'benchmark'

class User
  def self.find(id)
    sleep(0.5)
    puts "Finding user by id: #{id}..."
    id
  end
end

def current_user
  @current_user = User.find(1)
end

puts Benchmark.measure { 5.times { puts current_user } }
# Finding user by id: 1...
# Finding user by id: 1...
# Finding user by id: 1...
# Finding user by id: 1...
# Finding user by id: 1...
#   0.000000   0.000000   0.000000 (  2.500786)

def current_user
  @current_user ||= User.find(1)
end

puts Benchmark.measure { 5.times { puts current_user } }
# Finding user by id: 1...
#   0.000000   0.000000   0.000000 (  0.500157)