Why might it be necessary to create a custom exception type?

Creating your own exception type allows:

• To improve code readability and understanding: Exceptions with meaningful names explicitly indicate the nature of the error.
• To provide more granular error handling: You can catch and handle specific error types rather than general Exception.
• To pass additional error information: You can add attributes to your custom exception type to store contextual data.
• To create an error hierarchy: Organize related exceptions into a logical structure, making them easier to handle.

Example:

# Define a custom exception for invalid input
class InvalidInputError(ValueError):
    def __init__(self, message, value):
        super().__init__(message) # Call the base class constructor
        self.value = value # Store the problematic value

# Function that raises the custom exception
def process_input(data):
    if not isinstance(data, int):
        raise InvalidInputError("Input must be an integer", data) # Raise the custom exception
    return data * 2

# Example usage with exception handling
try:
    result = process_input("hello")
except InvalidInputError as e:
    print(f"Error processing input: {e.message}, value: {e.value}") # Access custom attributes