[Python-Dev] PEP 572 and assert

[Barry Warsaw]

On Jul 17, 2018, at 12:18, MRAB <python at mrabarnett.plus.com> wrote:

> Why use len(...) == 0 instead of not(...)?
> 
>    assert not(subdirs := list(path.iterdir())), subdirs

Off-topic, but it’s a style thing.  Some style guides (and my personal preference) require to be more explicit when checking for empty sequences.  I’ll use a boolean test (e.g. `not` or false-iness) when the subject could be empty, None, or the empty string, and `len() == 0` when the subject is supposed to be a sequence.

-Barry


-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 833 bytes
Desc: Message signed with OpenPGP
URL: <http://mail.python.org/pipermail/python-dev/attachments/20180717/ee5a6c64/attachment.sig>