Source code for can.exceptions

There are several specific :class:`Exception` classes to allow user
code to react to specific scenarios related to CAN busses::

    Exception (Python standard library)
     +-- ...
     +-- CanError (python-can)
         +-- CanInterfaceNotImplementedError
         +-- CanInitializationError
         +-- CanOperationError
         +-- CanTimeoutError

Keep in mind that some functions and methods may raise different exceptions.
For example, validating typical arguments and parameters might result in a
:class:`ValueError`. This should always be documented for the function at hand.

import sys
from contextlib import contextmanager

from typing import Optional
from typing import Type

if sys.version_info >= (3, 9):
    from import Generator
    from typing import Generator

[docs]class CanError(Exception): """Base class for all CAN related exceptions. If specified, the error code is automatically appended to the message: >>> # With an error code (it also works with a specific error): >>> error = CanOperationError(message="Failed to do the thing", error_code=42) >>> str(error) 'Failed to do the thing [Error Code 42]' >>> >>> # Missing the error code: >>> plain_error = CanError(message="Something went wrong ...") >>> str(plain_error) 'Something went wrong ...' :param error_code: An optional error code to narrow down the cause of the fault :arg error_code: An optional error code to narrow down the cause of the fault """ def __init__( self, message: str = "", error_code: Optional[int] = None, ) -> None: self.error_code = error_code super().__init__( message if error_code is None else f"{message} [Error Code {error_code}]" )
[docs]class CanInterfaceNotImplementedError(CanError, NotImplementedError): """Indicates that the interface is not supported on the current platform. Example scenarios: - No interface with that name exists - The interface is unsupported on the current operating system or interpreter - The driver could not be found or has the wrong version """
[docs]class CanInitializationError(CanError): """Indicates an error the occurred while initializing a :class:`can.BusABC`. If initialization fails due to a driver or platform missing/being unsupported, a :exc:`~can.exceptions.CanInterfaceNotImplementedError` is raised instead. If initialization fails due to a value being out of range, a :class:`ValueError` is raised. Example scenarios: - Try to open a non-existent device and/or channel - Try to use an invalid setting, which is ok by value, but not ok for the interface - The device or other resources are already used """
[docs]class CanOperationError(CanError): """Indicates an error while in operation. Example scenarios: - A call to a library function results in an unexpected return value - An invalid message was received - The driver rejected a message that was meant to be sent - Cyclic redundancy check (CRC) failed - A message remained unacknowledged - A buffer is full """
[docs]class CanTimeoutError(CanError, TimeoutError): """Indicates the timeout of an operation. Example scenarios: - Some message could not be sent after the timeout elapsed - No message was read within the given time """
[docs]@contextmanager def error_check( error_message: Optional[str] = None, exception_type: Type[CanError] = CanOperationError, ) -> Generator[None, None, None]: """Catches any exceptions and turns them into the new type while preserving the stack trace.""" try: yield except Exception as error: # pylint: disable=broad-except if error_message is None: raise exception_type(str(error)) from error else: raise exception_type(error_message) from error