Accepting Unlimited Arguments

Sometimes you don't know ahead of time how many items a user will pass into your function. For example, Python's built-in print() function can take 1 item, 5 items, or 100 items! You can create your own flexible functions using *args and **kwargs.

Positional Arguments (*args)

Adding an asterisk * before a parameter name gathers extra items into a Tuple:

def add_all(*numbers):
    # 'numbers' becomes a tuple of whatever items were passed
    return sum(numbers)

print(add_all(10, 20))          # Output: 30
print(add_all(5, 10, 15, 20))   # Output: 50

Keyword Arguments (**kwargs)

Adding two asterisks ** before a parameter name gathers named keyword items into a Dictionary:

def print_profile(**user_data):
    for key, value in user_data.items():
        print(f"{key}: {value}")

print_profile(name="Alice", role="Admin", country="India")

The Correct Order of Parameters

If your function uses regular inputs, default inputs, *args, and **kwargs all together, you must write them in this specific order:

def setup_user(standard_arg, default_arg="OK", *args, **kwargs):
    pass

1. Standard inputs (standard_arg)
2. Default inputs (default_arg="OK")
3. *args
4. **kwargs

Common Beginner Mistakes

• Order of *args and **kwargs: **kwargs must always be placed at the very end of the parameter list (def fn(*args, **kwargs):). Reversing them raises SyntaxError.

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Quick Summary

• *args (Variable Positional Arguments): Captures any number of positional arguments into a tuple.
• **kwargs (Variable Keyword Arguments): Captures any number of named key-value arguments into a dict.
• Parameter Ordering: def func(positional, *args, default="val", **kwargs):.
• Argument Spreading: Use * and ** during function calls to unpack lists and dicts into arguments.

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What's Next?

Let's explore one-line shortcut functions called lambdas and recursive self-calling functions in the next lesson!

Lambdas & Recursion

Learn concise one-line functions and self-referencing loops