Python Raise Statement

Python raise statement

Created By: chatGPT

Python's raise statement is used to trigger exceptions in your code. By raising exceptions, you can handle errors more gracefully, providing meaningful feedback to the user or developer. This is particularly useful for validating inputs or signaling unexpected issues in the application flow.

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

In this example, a function divide_numbers takes two arguments. If the second argument b is zero, it raises a ValueError. This prevents the function from attempting to perform an invalid operation, thus enforcing safe coding practices.

try:
    result = divide_numbers(10, 0)
except ValueError as e:
    print(f'Error: {e}')

When you use the raise statement within a try-except block, you can catch the raised exception and handle it accordingly. In the example above, attempting to divide by zero triggers the ValueError, which we catch and print a friendly error message.

def custom_error():
    raise Exception("This is a custom error message")

try:
    custom_error()
except Exception as e:
    print(e)

You can also define and raise your own custom exceptions. Here, the custom_error function raises a generic Exception with a custom message. This allows for clearer error handling, making it easier to identify specific issues within your code.

class MyCustomError(Exception):
    pass

try:
    raise MyCustomError("Something went wrong")
except MyCustomError as e:
    print(e)

Creating a custom exception class, like MyCustomError, makes it easy to distinguish between different types of errors in your application. When the custom exception is raised, it provides specific context about what went wrong, which can greatly aid in debugging.

def check_value(value):
    if value < 0:
        raise ValueError("Value must not be negative")
    return value

values = [-1, 0, 2]

for v in values:
    try:
        print(check_value(v))
    except ValueError as e:
        print(f'Error with value {v}: {e}')