Question

Edited

I originally asked about doing this in one line; I meant to say one statement. I’ve edited the question accordingly.

---

Suppose I have a method that returns a two-item array, like a color and a day of the week.

def make_tuple
  [['blue', 'red', 'orange'].sample, ['Mon','Wed', 'Fri'].sample]
end
make_tuple # =>  ['orange', 'Wed']

I can capture the output in two separate variables like this:

color, day = make_tuple

I can gather those outputs into two separate collections like this:

colors ||= []
days   ||= []
colors << color
days   << day

Is there a way to combine these two steps – getting separate values from the tuple and appending them to separate existing collections – into one statement? For instance:

# Doesn't work
colors <<, days << = make_tuple

Answer 1

Some examples, both functional and imperative style:

def make_tuple
  [['blue', 'red', 'orange'].sample, ['Mon','Wed', 'Fri'].sample]
end

# Functional creation of pairs with N elements
colors, days = 3.times.map { make_tuple }.transpose
#=> [["blue", "blue", "blue"], ["Wed", "Wed", "Mon"]]

# Functional append (creates new arrays)
colors2, days2 = [colors, days].zip(make_tuple).map { |ar, x| ar + [x] }
#=> [["blue", "blue", "blue", "red"], ["Wed", "Wed", "Mon", "Fri"]]

# Imperative append
[colors, days].zip(make_tuple) { |pair, p| pair << p } 
#=> [["blue", "blue", "blue", "red"], ["Wed", "Wed", "Mon", "Fri"]]

# Imperative append building an abstraction Array#zip_append
class Array
  def zip_append(items)
    zip(items) { |array, item| array << item }
  end
end

[colors, days].zip_append(make_tuple)
#=> [["blue", "blue", "blue", "red"], ["Wed", "Wed", "Mon", "Fri"]]