Which exception should I raise on bad/illegal argument combinations in Python?

You can raise the ValueError exception when you encounter bad or illegal argument combinations in Python. Here is an example code snippet:

def divide(a, b):
    if b == 0:
        raise ValueError("Cannot divide by zero.")
    return a / b

try:
    result = divide(10, 0)
except ValueError as e:
    print(e)

In this example, if the value of b passed to the divide function is 0, the ValueError exception is raised with the message "Cannot divide by zero." The try block surrounding the call to divide is used to catch and handle the exception, in this case printing the error message.

Watch a video course Python - The Practical Guide

Alternatively, you can use assert statement to check the input arguments before the operation, which is more efficient and will raise AssertionError if the condition is not met

def divide(a, b):
    assert b != 0, "Cannot divide by zero."
    return a / b

try:
    divide(10, 0)
except Exception as e:
    print(e)

It will raise AssertionError with the message "Cannot divide by zero."