User-Defined Exceptions in Python

User-defined exceptions in Python empower developers to create custom error types, enhancing the specificity and meaningfulness of error handling in their code.

What are Exceptions?

• Exceptions are events that disrupt the normal flow of a program.
• Python includes built-in exceptions, such as ValueError and TypeError, but there are scenarios where defining your own exception is beneficial.

Why Create User-Defined Exceptions?

• To handle specific errors pertinent to your application.
• To deliver more informative and relevant error messages.
• To implement custom error handling logic tailored to the unique needs of your application.

How to Define a User-Defined Exception

You can create a user-defined exception by subclassing the built-in Exception class.

Example:

class MyCustomError(Exception):
    """Custom Exception for specific errors"""
    pass

Raising a User-Defined Exception

You can raise your custom exception using the raise keyword when a specific condition is met.

Example:

def check_value(x):
    if x < 0:
        raise MyCustomError("Negative value error: Value must be non-negative")
    return x

Handling User-Defined Exceptions

To manage exceptions, you can use a try and except block. This allows your program to continue executing even when an error occurs.

Example:

try:
    check_value(-1)
except MyCustomError as e:
    print(e)  # Output: Negative value error: Value must be non-negative

Key Points

• Custom Exceptions: Create specific error types for enhanced clarity.
• Raising Exceptions: Utilize raise to trigger your exceptions.
• Handling Exceptions: Implement try and except blocks for graceful error handling.

By defining and utilizing user-defined exceptions, you can develop more robust and maintainable Python applications that manage errors in a controlled manner.