Message 390816 - Python tracker

Message390816

Author	andrei.avk
Recipients	BTaskaya, Mark.Shannon, andrei.avk, christian.heimes, josh.r, mark.dickinson, pablogsal, rhettinger, serhiy.storchaka, terry.reedy
Date	2021-04-12.04:09:08
SpamBayes Score	-1.0
Marked as misclassified	Yes
Message-id	<1618200548.75.0.00871119849192.issue42454@roundup.psfhosted.org>
In-reply-to

Content
One possibility for this being a breaking change is this scenario: some codebase may have logic that takes a list and uses a slice operation on it; in a rare circumstance the list is really a dict and a TypeError is caught upstream and dealt with; with this change it will no longer be caught/logged and the dict will be unexpectedly modified. It might also be hard to debug. I don't remember seeing such code but it's conceivable. The change might still be worth it for performance improvement though - I'm not sure.

Content

One possibility for this being a breaking change is this scenario: some codebase may have logic that takes a list and uses a slice operation on it; in a rare circumstance the list is really a dict and a TypeError is caught upstream and dealt with; with this change it will no longer be caught/logged and the dict will be unexpectedly modified. It might also be hard to debug. 

I don't remember seeing such code but it's conceivable.

The change might still be worth it for performance improvement though - I'm not sure.

History
Date	User	Action	Args
2021-04-12 04:09:08	andrei.avk	set	recipients: + andrei.avk, rhettinger, terry.reedy, mark.dickinson, christian.heimes, Mark.Shannon, serhiy.storchaka, josh.r, pablogsal, BTaskaya
2021-04-12 04:09:08	andrei.avk	set	messageid: <1618200548.75.0.00871119849192.issue42454@roundup.psfhosted.org>
2021-04-12 04:09:08	andrei.avk	link	issue42454 messages
2021-04-12 04:09:08	andrei.avk	create