Ruby & the Splat Operator

Seventh article in the Prepare for a Ruby job interview series. In this article, we’re going to talk about *, A.K.A the Splat operator, which is a great tool as we’ll see.

The splat operator is a very nice trick that let you do many things. Let’s see what!

1. When used in a function arguments, it will collect all the remaining arguments in an array.

def print_stuff(stuff, *arguments)
  p stuff
  arguments.each { |arg| p arg}
end

print_stuff('yes', 'no', 'maybe', 'what?')

# => "yes"
# => "no"
# => "maybe"
# => "what?"

2. Convert an array to arguments :

def add(a, b, c)
  p a + b + c
end

add(*[1, 2, 3])

# => 6

3. Create an array

stuff = *'Test'
p stuff

# => ["Test"]

4. Convert a hash to an array :

stuff = *{ a: 1, b: 2, c:3 }
p stuff

# => [[:a, 1], [:b, 2], [:c, 3]]

5. Assign multiple variables :

# You can also put it on the b variable
*a, b = [1, 2, 3, 4, 5]
p a
p b

# => [1, 2, 3, 4]
# => 5

6. Flatten an array

a = [1, 2, 3, 4, 5]
b = [*a, 6, 7]
p b

# => [1, 2, 3, 4, 5, 6, 7]

Checkout the next article about some cool Ruby tricks.