The Unpacking Operator * in Lists and Dictionaries

As Python code evolves, combining data structures becomes a frequent task.
Lists grow, dictionaries merge, arguments get forwarded.

The unpacking operators * and ** exist to make these operations clearer, safer, and more expressive.

Unpacking lists and tuples with *

numbers = [3, 4, 5]
combined = [1, 2, *numbers]

print(combined)
# [1, 2, 3, 4, 5]

This avoids manual concatenation and keeps the intent obvious.

Unpacking dictionaries with **

defaults = {"host": "localhost", "port": 5432}
overrides = {"port": 5433}

config = {**defaults, **overrides}
print(config)
# {'host': 'localhost', 'port': 5433}

Later values override earlier ones, which makes configuration patterns very natural.

Unpacking in function calls

def connect(host, port):
    print(host, port)

params = {"host": "localhost", "port": 5432}

connect(**params)

This is especially useful when passing data between layers or APIs.

Combining *args and **kwargs

def wrapper(*args, **kwargs):
    return target(*args, **kwargs)

Unpacking plays a key role in decorators and wrappers.

A common mistake to avoid

Avoid overusing unpacking when it hides logic:

# Harder to understand
data = [*get_items(), *get_more_items(), *get_even_more()]

If the source of data matters, explicit steps can be clearer.

Conclusion

In real-world Python, unpacking operators help reduce noise and clarify intent.

Used thoughtfully, * and ** make code easier to read and reason about — not more magical.