[Python-Dev] PEP 572 and assert

Barry Warsaw barry at python.org
Tue Jul 17 15:58:42 EDT 2018

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.


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