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Add PYTHONDEVMODE=1 to enable the developer mode #76282
Description
| BPO | 32101 |
|---|---|
| Nosy | @ncoghlan, @pitrou, @vstinner |
| PRs |
Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.
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GitHub fields:
assignee = None
closed_at = <Date 2017-11-30.10:49:45.114>
created_at = <Date 2017-11-21.02:58:57.806>
labels = ['type-feature', '3.7']
title = 'Add PYTHONDEVMODE=1 to enable the developer mode'
updated_at = <Date 2017-12-12.22:15:02.111>
user = 'https://github.com/vstinner'bugs.python.org fields:
activity = <Date 2017-12-12.22:15:02.111>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2017-11-30.10:49:45.114>
closer = 'vstinner'
components = []
creation = <Date 2017-11-21.02:58:57.806>
creator = 'vstinner'
dependencies = []
files = []
hgrepos = []
issue_num = 32101
keywords = ['patch']
message_count = 6.0
messages = ['306618', '306625', '307195', '307284', '307286', '308162']
nosy_count = 3.0
nosy_names = ['ncoghlan', 'pitrou', 'vstinner']
pr_nums = ['4478', '4624', '4821']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue32101'
versions = ['Python 3.7']
Activity
vstinner commentedon Nov 21, 2017
In the review of the PR 4478, Antoine Pitrou proposed to add an environment variable to enable the new Python "developer mode" to inherit the developer mode in child Python processes.
I proposed to add PYTHONDEVMODE=1. Nick Coghlan proposed PYTHONXOPTIONS=dev.
While -X is a new "catch all" for new CPython options, Python got new PYTHONxxx environment variables to enable new options:
I have a preference for PYTHONDEVMODE=1.
If we start to use PYTHONXOPTIONS, users may want to use PYTHONXOPTIONS=tracemalloc, and then we have to decide which environment variable has the preference :-(
Moreover, tracemalloc takes an argument, whereas environment variables with a value containing '=' are rare and so likely to cause issues in programs not carefully written to handle such variables. (Environment variables are inherited by all processes, not only Python processes.)
ncoghlan commentedon Nov 21, 2017
Another argument against PYTHONXOPTIONS is that each implementation is free to decide which -X options it wants to support, and we don't really define what they're supposed to do with options they don't recognise.
By contrast, there's an established behaviour for unknown environment variables: implementations that don't support them just ignore them.
So +1 for PYTHONDEVMODE=1 from me - that also gives us more flexibility if we decide to add arguments to the option later.
vstinner commentedon Nov 29, 2017
While implementing a new PYTHONDEVMODE environment variable, I found that it would help to also add a new sys.flags.dev_mode flag. So I added it.
So for example, asyncio uses sys.flags.dev_mode rather than checking for 'dev' in sys._xoptions *and* check if the environment variable is set or not.
vstinner commentedon Nov 30, 2017
New changeset 5e3806f by Victor Stinner in branch 'master':
bpo-32101: Add PYTHONDEVMODE environment variable (bpo-4624)
5e3806f
vstinner commentedon Nov 30, 2017
Thanks Antoine and Nick for reviews and the feedback!
vstinner commentedon Dec 12, 2017
New changeset 721e25c by Victor Stinner in branch 'master':
bpo-32101: Fix tests for PYTHONDEVMODE=1 (bpo-4821)
721e25c