Use Exceptions with Notes

[nstarman]

What is the problem this feature will solve?

This is a Meta issue to encourage contributors new and well-seasoned to consider where Astropy can use Exceptions with Notes. One good category is wherever we catch an error, modify the message, and re-raise the same error, e.g. in #16878.

Describe the desired outcome

Please open PRs making our Exception messages more useful!

Additional context

EDIT: Would be much easier to wait for the following bumps first:

• requires-python = ">=3.11"
• pytest>=8.0

This change might also break downstream testing for our exception message with rigid match. Actual impact is unknown.

[neutrinoceros]

Exception.add_note is new in Python 3.11 IIRC, and we still support 3.10, so it might be a bit early for PRs, right ?

[nstarman]

sys.version_info a la https://github.com/astropy/astropy/pull/16878

[pllim]

So, is the ask here to use "notes" or to use "raise from"?

I think I am going to remove "good first issue". We need to actually pinpoint what code can be improved with this ask before asking new contributors to implement. Thanks for your understanding.

[pllim]

This might break downstream if they actually look for specific error messages, so we should probably consider the cost/benefit on a case by case basis.

[nstarman]

use "notes" or to use "raise from"

The former. Add notes. This shouldn't change the starts of any messages as notes are appended after the error message.

[mhvk]

This shouldn't change the starts of any messages as notes are appended after the error message.

Indeed, this is why I liked it so much (even if AttributeError is perhaps not the most logical).

But #16884 made clear that as long as we do not require pytest >= 8.0, one has to be careful, since the notes do not get added to the exception message that pytest sees.

[pllim]

Based on the conversation so far, I added stuff to "additional details" section in the original post above. Hope you don't mind!

[neutrinoceros]

I forgot about this, but note that we have a helper function astropy.utils.exceptions._add_note_to_exception whose whole purpose is to handle older Python versions transparently.

[mhvk]

I forgot about this, but note that we have a helper function astropy.utils.exceptions._add_note_to_exception whose whole purpose is to handle older Python versions transparently.

Yikes! Though hopefully it will soon become irrelevant as we drop python 3.10 -- #16900

[neutrinoceros]

Yup, I'm removing it in #16903

[pllim]

Just for my own future reference, astropy.utils.exceptions._add_note_to_exception was added in https://github.com/astropy/astropy/pull/16346 that was also milestoned to v7.0