How can I detect if Python is running in Python Development Mode?

Question

To turn on Python Development Mode, you can use this flag:

python3 -X dev example.py

or use this environment variable:

PYTHONDEVMODE=1 python3 example.py

How can I write code within example.py to detect whether Python is running in Python Development Mode or not?

Does this answer your question? [Check if my application runs in development/editable mode](https://stackoverflow.com/questions/40530000/check-if-my-application-runs-in-development-editable-mode) — Simon Hostettler, Oct 23 '20 at 14:01
if you use the environment var method you could check `os.environ` — rioV8, Oct 23 '20 at 14:09
@SimonHostettler No, that doesn't answer my question, as that question talks about editable mode, not Python Development Mode. — Flimm, Oct 23 '20 at 14:23
@rioV8 The variable `__debug__` is True even when Python Development Mode is not on. I just tried it by running `python3` and then running `python3 -X dev` — Flimm, Oct 23 '20 at 14:24
It's a bit of a hacky solution, but you should be able to do it by raising one of the exceptions that wouldn't be visible unless you're in development mode, like `DeprecationWarning`. — ades, Jan 16 '22 at 13:51

score 1 · Accepted Answer · edited Jan 16 '22 at 14:20

1

sys.flags.dev_mode is True, when running as python -X dev app.py

edited Jan 16 '22 at 14:20

Syscall

answered Jan 16 '22 at 13:34

Sameera K

1 Answers1