Wow that’s neat! Thanks for bringing this up.

The feature flags example should be rewritten to use enum.Flag

a use case – feature flags

Mix and match to plan your day

will i be going home today?

>>> OUTRAGED_BY_NEWS = 0b00000001
>>> GET_A_COFFEE = 0b00000010
>>> GO_FOR_A_HIKE = 0b00000100
>>> GO_FOR_A_RUN = 0b00001000
>>> GO_HOME = 0b00010000 
>>> various_flags_ored_together = GET_A_COFFEE | GO_FOR_A_RUN | GO_HOME
>>> various_flags_ored_together & GO_HOME == GO_HOME
True
>>> various_flags_ored_together & GO_FOR_A_HIKE == GO_FOR_A_HIKE
False
>>> various_flags_ored_together = GET_A_COFFEE | GO_FOR_A_RUN | GO_HOME
>>> bin(various_flags_ored_together)
'0b11010'
>>> various_flags_ored_together & OUTRAGED_BY_NEWS == OUTRAGED_BY_NEWS
>>> False
>>> bin(OUTRAGED_BY_NEWS)
>>> '0b1'
>>> various_flags_ored_together >> OUTRAGED_BY_NEWS
>>> bin(various_flags_ored_together)
'0b1101'

Guess haven’t gone for a hike today…maybe tomorrow

right shift removes bit at flag position. Which, in this case, happens to correspond to the right most bit.

use case – file access permissions

For those looking to check file access permissions there is the stat module

>>> import stat
>>> from pathlib import Path
>>> path_f = Path.home().joinpath(".bashrc")
>>> stat.S_IRUSR
256
>>> path_f.stat().st_mode
33188
>>> is_owner_read = path_f.stat().st_mode & stat.S_IRUSR == stat.S_IRUSR
>>> is_owner_read
True
>>> path_f = Path("/etc/fstab")
>>> is_other_write = path_f.stat().st_mode & stat.S_IWOTH == stat.S_IWOTH
>>> is_other_write
False

Assumes ~/.bashrc exists, if not choose a different file you are owner and have read access to.

path_f.stat().st_mode & stat.S_IRUSR == stat.S_IRUSR

Looking thru the mundane file (not Linux access control list) permissions. All those flags are crammed into st_mode. In st_mode, on/off bit at 2^8 is that on?

Sources

read user access stat.S_IRUSR

write others access stat.S_IWOTH

os.stat_result

pathlib.Path.stat

Sorry

Is that a quote from Forest Gump movie?

Slightly healthier words of wisdom

Only so much humor can take on an empty stomach

from multiprocessing import Lock
l = Lock()

flake8 … way too ambiguous

so what if it’s 100x slower /nosarc

The sample code for lazy imports looks wrong

STRIPE = None

def _stripe():
    global STRIPE
    if STRIPE is None:
        import stripe

        return stripe
    return STRIPE

STRIPE is never changed. And two return statements in the same function?!

Anyways can imagine how to do lazy imports without relying on the given code sample.