FizzBuzz.rb

# 定義一個 Porc 物件把 block 包起來，當呼叫的時候會在裡面做運算並回傳布林值(true or false)
divisible_by_15 = proc { |number| (number % 15).zero? }
divisible_by_5 = proc { |number| (number % 5).zero? }
divisible_by_3 = proc { |number| (number % 3).zero? }

num = 9

case num
# when 會呼叫 divisible_by_15 的 === 方法，將 num 作為引數傳進去
# divisible_by_15 === 9
when divisible_by_15
  puts "FizzBuzz"
when divisible_by_5
  puts "Buzz"
when divisible_by_3
  puts "Fizz"
else
  puts num
end
# Fizz