FizzBuzz from a casual rubyist

Question

As a casual Rubyist I am mainly interested, how ideomatic my solution is.

class Integer
  def divisible_by?(n)
    (self % n).zero?
  end
end

def fizzbuzz(upper_bound)
  1.upto(upper_bound).map do |number| 
    next "fizzbuzz" if number.divisible_by? 3 and number.divisible_by? 5
    next "fizz" if number.divisible_by? 3
    next "buzz" if number.divisible_by? 5
    next number
  end
end

puts fizzbuzz 100

Remarks: I borrowed the idea for monkeypatching Integer from @tokland here

Answer 1

If you're aiming for readability rather than efficiency or maintainability — and that is a reasonable tradeoff for FizzBuzz — then I would say "Well done." (You could test for divisibility by 15 for efficiency and avoid monkey-patching for maintainability.)

Conventionally, the output should be one entry per line, rather than an array.

If you're going to take an upper bound as a parameter, you may as well take a range, and the parameter should default to 1..100.

Therefore, a better way to call the code would be

fizzbuzz(1..100).each { |output| puts output }

or, using the default,

fizzbuzz.each { |output| puts output }

Answer 2

Since we have hardcoded the divisor as 3 and 5, we could do this:

next "fizzbuzz" if number.divisible_by? 15

If you wish to go by the fact that your program should dictate the problem as it is, we could use the following:

• use a flag: isFizz = (num%3 == 0)
• use a flag: isBuzz = (num%5 == 0)
• use the boolean to decide the output.

Analyse the number of times the modulo operation is performed here:

// for n numbers
next "fizzbuzz" if number.divisible_by? 3 and number.divisible_by? 5

100 times (once for each number) + 33 times (if number.divisible_by? 3 will be true 33 times and thus the second operation will be performed)

next "fizz" if number.divisible_by? 3

fizzbuzz above will be false 94 times, so this will happen 94 times.

next "buzz" if number.divisible_by? 5

fizz above will be false 67 times, so this will happen 67 times.

Total = 100 + 33 +94 + 67 = 267

For using 15 , total = 234

Using the booleans that I suggested, you will end up with 200