Python Keyword Arguments – Write Clear and Flexible Functions

Introduction – Why Keyword Arguments Matter

When calling functions in Python, we often use positional arguments. But in many real-world scenarios—like APIs, configuration options, or user input—order shouldn’t matter.

That’s where keyword arguments shine.

They allow you to call a function by explicitly naming parameters, improving readability and making arguments order-independent.

In this guide, you’ll learn:

• What keyword arguments are and how to use them
• Differences from positional arguments
• How to mix positional and keyword arguments
• Real-world examples and best practices

Syntax of Keyword Arguments

def function_name(param1, param2):
    # code

function_name(param1=value1, param2=value2)

Key Rule: Parameter names must match those in the function definition.

Example 1: Simple Keyword Arguments

def introduce(name, age):
    print(f"My name is {name} and I am {age} years old.")

introduce(age=25, name="Alice")

Output:

My name is Alice and I am 25 years old.

Explanation:
Using keywords lets you pass arguments in any order.

Positional vs Keyword Arguments

Mixing Positional and Keyword Arguments

Example 2:

def book_flight(from_city, to_city, airline="Delta"):
    print(f"Flight from {from_city} to {to_city} via {airline}")

book_flight("Paris", to_city="New York")

Rule:
Positional arguments must come before keyword arguments.

This is valid:

func(10, b=5)

This is invalid:

func(a=10, 5)  # SyntaxError

Real-World Example: Sending Email

def send_email(to, subject, body="(No Content)", cc=None):
    print(f"To: {to}")
    print(f"Subject: {subject}")
    print(f"Body: {body}")
    print(f"CC: {cc or 'None'}")

send_email(subject="Update", to="user@example.com", cc="boss@example.com")

Use Case: Keyword arguments are perfect when calling functions with many optional parameters.

Common Mistakes

Summary – Key Takeaways

• Keyword arguments let you assign values by name, not position
• You can mix positional and keyword arguments (positional first)
• Ideal for optional and named parameters
• Keyword arguments improve readability and flexibility

FAQ Section

Can keyword arguments be in any order?

Yes, as long as parameter names match, order doesn’t matter.

Can I use only keyword arguments?

Yes. You can call a function with all keyword arguments:

introduce(name="Bob", age=30)

What happens if I misspell a keyword?

Python will raise a TypeError:

TypeError: got an unexpected keyword argument

Can keyword arguments be combined with default arguments?

Yes. They often go hand-in-hand for better flexibility.

Are keyword arguments required?

No. They are optional unless specified using special syntax like *, (Python 3.8+).