Positional Arguments

Overview

Positional arguments are matched to parameters by position (left to right). They are the most basic and common argument type — used in virtually every function call. Understanding their order requirements prevents common TypeError bugs.

Syntax

python

def connect(host: str, port: int, timeout: float):
    return f"Connecting to {host}:{port} (timeout={timeout}s)"

# Positional — order matters
connect("localhost", 5432, 30.0)

# You can also pass positionally by keyword (named)
connect("localhost", timeout=30.0, port=5432)  # same result

# Positional-only params (Python 3.8+, before /)
def add(x, y, /):   # x and y can ONLY be positional
    return x + y

Common Pitfalls

Positional arguments are required unless they have a default value — missing one raises TypeError.
Once you use a keyword argument in a call, all subsequent arguments must also be keyword.
Interview tip: Function signature order convention: required positionals → optional with defaults → *args → keyword-only → **kwargs.

Real-World Example

Database connection factory using positional argument ordering

example

python

def create_connection(
    host: str,
    port: int,
    database: str,
    user: str = "admin",
    password: str = "",
) -> dict:
    return {
        "host": host, "port": port,
        "database": database, "user": user,
        "password": password,
    }

# All positional
conn = create_connection("db.example.com", 5432, "mydb")
print(conn)

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