Using a Walrus Operator in If Statement Does Not Work
I Have a Simple Function That Should Output a Prefix Based on a Pattern or None If It Does Not Match. Trying to Do a Walrus It Does Not Seem to Work. Any Idea?...
I have a simple function that should output a prefix based on a pattern or None if it does not match. Trying to do a walrus it does not seem to work. Any idea?
import re
def get_prefix(name):
if m := re.match(f'^.+(\d\d)-(\d\d)-(\d\d\d\d)$', name) is not None:
return m.group(3) + m.group(2) + m.group(1)
get_prefix('abc 10-12-2020')
Traceback
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "<stdin>", line 3, in get_prefix
AttributeError: 'bool' object has no attribute 'group'
1 Answer
You're setting m to re.match(f'^.+(\d\d)-(\d\d)-(\d\d\d\d)$', name) is not None, which is a boolean.
You probably mean
if (m := re.match(f'^.+(\d\d)-(\d\d)-(\d\d\d\d)$', name)) is not None:
But you don't need is not None here anyway. Matches are truthy and None is falsey. So you just need:
if m := re.match(f'^.+(\d\d)-(\d\d)-(\d\d\d\d)$', name):
(Arguably it's better practice to use () whenever you're using an assignment expression, to make clear what's being assigned.)
Elena Rostova holds a Master's degree in Public Health Journalism. She covers groundbreaking medical research, holistic wellness trends, mental health awareness, and nutritional science.
