FizzBuzz in GNU make – DEV Neighborhood

Once I could not go to sleep final evening ¹ my sleep-deprived mind all of a sudden went “I wager you’ll be able to’t write a Makefile for FizzBuzz.” Whereas I clearly ought to have responded with Homer Simpson’s basic “Shut up, mind, or I am going to stab you with a Q-tip.”, it was too late, I had already nerd sniped myself. I totally anticipated to waste approach an excessive amount of time on this nevertheless it solely (?) took slightly over an hour to provide you with an answer.

The Makefile

With out additional ado, here is the factor that ought to most likely by no means have occurred:

START := 1
END := 15
NUMS := $(shell seq $(START) $(END))

fizzbuzz: $(NUMS)

mod = $(shell echo $$(( $1 % $2 )))

outline fb
$1:
ifeq "$(name mod, $1, 15)" '0'
    @echo FizzBuzz
else ifeq "$(name mod, $1, 3)" '0'
    @echo Fizz
else ifeq "$(name mod, $1, 5)" '0'
    @echo Buzz
else
    @echo $1
endif
endef

$(foreach _,${NUMS},$(eval $(name fb,$_)))

.PHONY: fizzbuzz $(NUMS)

Let’s examine it in motion:

$ make fizzbuzz
1
2
Fizz
4
Buzz
Fizz
7
8
Fizz
Buzz
11
Fizz
13
14
FizzBuzz

Since fizzbuzz is the primary goal we are able to depart it off. And we are able to additionally override START and END from the command line:

$ make START=19 END=30
19
Buzz
Fizz
22
23
Fizz
Buzz
26
Fizz
28
29
FizzBuzz

Walkthrough

So how does this work? We begin by defining a bunch of variables for the beginning and finish values of the quantity vary we need to examine:

START := 1
END := 15

Subsequent we use the shell perform to assemble a sequence of numbers with seq, so NUMS will include 1 2 3 [...] 14 15.

Now we are able to arrange a fizzbuzz goal and record all of the numbers in NUM as stipulations:

fizzbuzz: $(NUMS)

Subsequent up, slightly helper perform for modulo, since make itself does not assist arithmetic operations. This makes use of the shell’s arithmetic enlargement mechanism and doesn’t depend on exterior packages like bc.

mod = $(shell echo $$(( $1 % $2 )))

Now for the enjoyable half 🙂 First, we use outline to, properly, outline a sequence of make expressions that we’ll later eval to show them into targets:

outline fb
$1:
ifeq "$(name mod, $1, 15)" '0'
    @echo FizzBuzz
else ifeq "$(name mod, $1, 3)" '0'
    @echo Fizz
else ifeq "$(name mod, $1, 5)" '0'
    @echo Buzz
else
    @echo $1
endif
endef

The code ought to be comparatively easy: we confer with this block of assertion as fb when calling it and $1 will obtain the worth of the primary argument. Then we do a few ifeq checks ²

Now we are able to use foreach together with eval and name to outline targets for all the person numbers:

$(foreach _, ${NUMS}, $(eval $(name fb, $_)))

Final however not least, let’s declare all targets as phony to point that they do not associated to actual information.

Abstract

Whereas I most likely want higher hobbies, this was a enjoyable solution to kill a while and I undoubtedly realized a bit extra about make at the moment. When a pal (hello, Joe 👋) requested me why I did this, my reply was clear: “As a result of I might.” Hack on everybody and do not forget to have enjoyable with expertise!

1. I’ve handled insomnia just about since childhood. ↩

2. I might usually keep away from the modulo 15 examine however that will get awkward in make since there aren’t actually any native variables.  ↩