Multiple Assignment: Unpack Everything in One Shot

2026-03-21

Ruby's multiple assignment lets you pull apart arrays, swap variables, skip fields, and destructure nested data in a single line. If you've been writing my ($ip, $port) = split(/:/, $line) in Perl, you already get the concept. Ruby just takes it further.

Part 1: Basic Multiple Assignment

# Assign multiple variables at once
a, b, c = 1, 2, 3

# Swap without temp variable
a, b = b, a
# Perl: ($a, $b) = ($b, $a);

# Unpack from split
ip, port = line.split(":")
# Perl: my ($ip, $port) = split(/:/, $line);

Part 2: Skipping Fields with Underscore

Use _ to discard unwanted values:

# Skip fields (like /etc/passwd parsing)
_, user, _, home = passwd_line.split(":")
# Perl: my (undef, $user, undef, $home) = split(/:/, $line);

# Skip first element
_, *rest = array

# Skip return values
_, result = method_returning_two_values

Perl uses undef as a placeholder. Ruby uses _. Shorter, cleaner, same idea.

Part 3: Nested Destructuring

Ruby can unpack nested arrays in one assignment:

# Nested array unpacking
(a, b), c, d = [[1, 2], 3, [4, 5]]
# a => 1, b => 2, c => 3, d => [4, 5]

# Deep nesting
((a, b), c), d = [[[1, 2], 3], 4]
# a => 1, b => 2, c => 3, d => 4

Perl equivalent: manual unpacking with array refs. Ruby does it automatically in one expression. That's not a small difference when you're parsing structured data.

Part 4: Destructuring in Block Parameters

# Hash iteration gives [key, value] pairs
hash.each do |key, value|
  puts "#{key}: #{value}"
end

# Nested data structures
data = [[[1, 2], "info"], [[3, 4], "more"]]
data.each do |(coords, label)|
  x, y = coords
  puts "#{label}: #{x}, #{y}"
end

Part 5: Multiple Return Values

Ruby methods can return multiple values (actually returns an array that auto-unpacks):

def get_stats(data)
  min = data.min
  max = data.max
  avg = data.sum / data.size.to_f
  return min, max, avg     # returns [min, max, avg]
end

minimum, maximum, average = get_stats(numbers)
# Perl: my ($min, $max, $avg) = get_stats(@numbers);

Part 6: Practical Examples

# Parse key=value lines
key, value = line.split("=", 2)

# Parse Apache log fields
ip, _, _, timestamp, request, status, size = line.split(" ", 7)

# Unpack CSV with headers
header = lines.first.split(",")
lines[1..].each do |line|
  fields = line.split(",")
  # zip headers with fields
  record = header.zip(fields).to_h
end

Multiple assignment is one of those features that makes Ruby code visually obvious. You see the shape of the data on the left side of the = and immediately understand what's being extracted.