Tuple Unpacking

Overview

Tuple unpacking (destructuring) lets you assign multiple variables from a sequence in one line. It works with any iterable and enables clean swap syntax, function multi-returns, and starred expressions.

Syntax

python

# Basic unpacking
x, y = (3, 4)
a, b, c = [1, 2, 3]
first, second = "hi"   # works on strings too!

# Swap without temp variable
a, b = b, a

# Starred unpacking (extended)
first, *rest = [1, 2, 3, 4, 5]
# first = 1, rest = [2, 3, 4, 5]

*init, last = [1, 2, 3, 4, 5]
# init = [1, 2, 3, 4], last = 5

Common Pitfalls

The number of variables must match the iterable length unless using * — mismatch raises ValueError.
Only one starred expression is allowed per unpacking statement.
Interview tip: Swapping with tuple unpacking (a, b = b, a) is more Pythonic than using a temp variable and is a common interview test.

Real-World Example

Unpack CSV row data into named variables for clean processing

example

python

import csv
from pathlib import Path

def process_csv(path: str) -> None:
    with open(path) as f:
        reader = csv.reader(f)
        next(reader)  # skip header
        for name, age, email, *extras in reader:
            age = int(age)
            print(f"{name} ({age}): {email}")

# Swap example — classic interview trick
a, b = 1, 2
a, b = b, a
print(a, b)  # 2 1

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