Creating Custom Exceptions

Python allows you to define custom exceptions to handle specific error conditions within your application. This provides a more granular way to manage errors and improve code readability.

Steps to Create a Custom Exception:

1. Import the Exception class:
   • Python
   • from exceptions import Exception
2. Create a new class:
   • Python
   • class MyCustomError(Exception):
   • pass
3. Raise the exception:
   • Python
   • raise MyCustomError("This is a custom error message")
4. Handle the exception:
   • Python
   • try:
   • # Code that might raise the custom exception except MyCustomError as e: print(f"Caught a custom error: {e}")

Example:

Python

class NegativeValueError(Exception):
    """Raised when a value is negative"""
    pass

def calculate_square_root(number):
    if number < 0:
        raise NegativeValueError("Number cannot be negative")
    else:
        return number**0.5

try:
    result = calculate_square_root(-4)
except NegativeValueError as e:
    print(e)

Additional Considerations:

• Inheritance: You can create hierarchies of custom exceptions by inheriting from other exception classes.
• Custom attributes: Add attributes to your custom exception class to provide additional information about the error.
• Error messages: Provide clear and informative error messages in the exception’s constructor.
• When to use custom exceptions: When standard exceptions don’t accurately represent the error condition.

By defining custom exceptions, you can improve error handling and make your code more readable and maintainable.

Creating Custom Exceptions

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