Sometimes it is necessary to both customize and raise exceptions in your code. When you do this, you should always include a meaningful error message to indicate what the source of the error is. This makes your code more readable and helps significantly with debugging.
Custom exceptions can be created through new exception classes (see classes for more detail.) that are typically subclasses of Exception.
For situations where you know the error source will be a derivative of a certain exception type, you can choose to inherit from one of the built in error types under the Exception class. When raising the error, you should still include a meaningful message.
This particular exercise requires that you create two custom exceptions. One exception to be raised/"thrown" when your circular buffer is full, and one for when it is empty. The tests will only pass if you customize appropriate exceptions, raise those exceptions, and include appropriate error messages.
To customize a built-in exception, create a class that inherits from that exception. When raising the custom exception with a message, write the message as an argument to the exception type:
# subclassing the built-in BufferError to create BufferFullException
class BufferFullException(BufferError):
"""Exception raised when CircularBuffer is full.
message: explanation of the error.
"""
def __init__(self, message):
self.message = message
# raising a BufferFullException
raise BufferFullException("Circular buffer is full")