Python Function Parameters: Combining Types, Rules and Examples

Combining Different Parameter Types in Python – Part 2 [Intermediate]

Part 2 extends the parameter combinations covered in Part 1 by showing how *args and **kwargs can be used when combining function parameters in Python.

These parameter types have different jobs:

• Positional-only parameters must be passed by position.
• Regular parameters can be passed by position or keyword.
• *args collects extra positional arguments.
• Keyword-only parameters must be passed by keyword.
• **kwargs collects extra keyword arguments.

The following combinations show how these parameter types work together:

• Regular + *args
• *args + Keyword-Only Parameters
• Regular + *args + **kwargs
• Positional-Only + *args + Keyword-Only
• Positional-Only + Regular + *args + Keyword-Only + **kwargs
• Complete Parameter Order

Regular + *args

A regular parameter can appear before *args. The regular parameter receives its normal argument, while *args collects additional positional arguments.

Example

def show_values(name, *args):
    print("Name:", name)
    print("Other values:", args)

show_values("Alice", 10, 20, 30)


# Output:
Name: Alice
Other values: (10, 20, 30)

Explanation: Here, name is a regular parameter. The additional positional arguments are collected in args.

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*args + Keyword-Only Parameters

Parameters written after *args are keyword-only parameters. This is an important difference from using a standalone *.

Example

def show_values(*args, total):
    print("Values:", args)
    print("Total:", total)

show_values(10, 20, 30, total=60)


# Output:
Values: (10, 20, 30)
Total: 60

Explanation: Here, args collects the positional arguments. The total parameter appears after *args, so it is keyword-only.

Error: Passing a Keyword-Only Parameter by Position

The following call incorrectly passes the total parameter by position instead of using its keyword.

show_values(10, 20, 30, 60)


# Error:
TypeError

Explanation: The value 60 is treated as another positional argument and is collected by *args. The required total keyword-only parameter is therefore not supplied.

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Regular + *args + **kwargs

A function can use a regular parameter, *args, and **kwargs together.

Example

def show_values(name, *args, **kwargs):
    print("Name:", name)
    print("Extra positional:", args)
    print("Extra keyword:", kwargs)

show_values(
    "Alice",
    10,
    20,
    age=25,
    city="Delhi"
)


# Output:
Name: Alice
Extra positional: (10, 20)
Extra keyword: {'age': 25, 'city': 'Delhi'}

Explanation: Here, name receives the first positional argument. The remaining positional arguments go into args. The extra keyword arguments go into kwargs.

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Positional-Only + *args + Keyword-Only

You can also combine positional-only parameters with *args and keyword-only parameters.

Example

def func(a, /, *args, c):
    print("a:", a)
    print("args:", args)
    print("c:", c)

func(10, 20, 30, c=40)


# Output:
a: 10
args: (20, 30)
c: 40

Explanation: Here,

• a is positional-only.
• *args collects additional positional arguments.
• c is keyword-only.

The c parameter is keyword-only because it appears after *args.

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Positional-Only + Regular + *args + Keyword-Only + **kwargs

Python allows all five parameter types in one function. This combination is useful when a function needs strict control over some arguments while still accepting additional arguments.

Example

def func(a, /, b, *args, c, **kwargs):
    print("a:", a)
    print("b:", b)
    print("args:", args)
    print("c:", c)
    print("kwargs:", kwargs)

func(
    10,
    20,
    30,
    40,
    c=50,
    color="blue",
    active=True
)


# Output:
a: 10
b: 20
args: (30, 40)
c: 50
kwargs: {'color': 'blue', 'active': True}

Explanation: Each part has a different job:

• a is positional-only.
• b is regular.
• *args collects additional positional arguments.
• c is keyword-only.
• **kwargs collects additional keyword arguments.

The call follows the same order. The first positional value goes to a. The second goes to b. The remaining positional values go to args. The c=50 argument goes to the keyword-only parameter, while the remaining keyword arguments go into kwargs.

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