Question

I am writing some Python code that uses a library to communicate with an external piece of hardware over USB. When the hardware library is unable to connect to the device, it returns False – otherwise it returns True.

I would like to examine this return and use it to trigger an exception – to be more Pythonic. What would be the most appropriate exception type to throw?

Answer 1

An IOError. From the docs:

Raised when an I/O operation (such as a print statement, the built-in
open() function or a method of a file object) fails for an I/O-related
reason, e.g., “file not found” or “disk full”.

You may want to wrap this in your own exception like:

 class ExternalDeviceNotFound(IOError): pass

and raise that instead. This gives the calling code more options on how to handle the error.