Python kwargs best practices

Python kwargs (keyword arguments) best practices refer to guidelines and recommendations for effectively using and handling keyword arguments in Python functions. Here are some commonly followed best practices:

These best practices will help you write clean, readable, and maintainable code when working with kwargs in Python.

The syntax for working with kwargs in Python is as follows:

Function Definition:

def my_function(**kwargs):
    # Function body

Function Call:

my_function(arg1=value1, arg2=value2, ...)

• In the function definition, the parameter is prefixed with two asterisks (**). This indicates that the function can accept an arbitrary number of keyword arguments.
• Inside the function, the keyword arguments are treated as a dictionary, where the argument names act as keys, and the corresponding values are the argument values.
• When calling the function, keyword arguments are specified using the arg_name=value syntax.

Here’s an example that demonstrates the usage of kwargs:

def greet(**kwargs):
    if 'name' in kwargs:
        print(f"Hello, {kwargs['name']}!")
    else:
        print("Hello, stranger!")

greet(name="Alice")  # Output: Hello, Alice!
greet()              # Output: Hello, stranger!

In the above example, the greet function accepts kwargs and checks if the 'name' key is present. If it is, it prints a personalized greeting using the corresponding value. Otherwise, it prints a generic greeting.

Python kwargs best practices example

Here’s an example that demonstrates the best practices for working with kwargs in Python:

def calculate_discounted_price(base_price, **kwargs):
    """
    Calculates the discounted price based on the base price and any additional kwargs provided.

    Keyword Arguments:
    - percentage_discount (float): The percentage discount to apply.
    - fixed_discount (float): The fixed discount amount to subtract.

    Returns:
    float: The discounted price.
    """
    discounted_price = base_price

    if 'percentage_discount' in kwargs:
        percentage_discount = kwargs['percentage_discount']
        discounted_price -= base_price * (percentage_discount / 100)

    if 'fixed_discount' in kwargs:
        fixed_discount = kwargs['fixed_discount']
        discounted_price -= fixed_discount

    return discounted_price


base_price = 100.0

dp1 = calculate_discounted_price(base_price, percentage_discount=20.0)
print(f"Discounted Price 1: ${dp1}")

dp2 = calculate_discounted_price(base_price, fixed_discount=10.0)
print(f"Discounted Price 2: ${dp2}")

dp3 = calculate_discounted_price(base_price, percentage_discount=15.0, fixed_discount=5.0)
print(f"Discounted Price 3: ${dp3}")

Output:

In the example above, the calculate_discounted_price function calculates the discounted price based on a base price and additional keyword arguments. Here are the best practices followed in this example:

1. The function is well-documented, providing information about the purpose, expected types, and return value.
2. The kwargs are explicitly named and described in the function signature, including their expected types.
3. The function validates the presence of specific keyword arguments (percentage_discount and fixed_discount) using the in keyword.
4. The function handles each keyword argument appropriately, applying the corresponding discount to the base price.
5. The function returns the final discounted price.

Note: IDE: PyCharm 2021.3.3 (Community Edition)

Windows 10

Python 3.10.1

All Python Examples are in Python 3, so Maybe its different from python 2 or upgraded versions.