[BUG] attribute names `awehoi234_wdfjwljet234_234wdfoijsdfmmnxpi492` and `_fields` make unrelated modules hard to debug

[reidpr]

• I've checked docs and closed issues for possible solutions.
• I can't find my issue in the FAQ.

Describe the bug

I have some code that I was debugging and was confused by the appearance of attributes called awehoi234_wdfjwljet234_234wdfoijsdfmmnxpi492 and _fields. This was pretty hard to debug. It turned out that these are both added by rich.

• awehoi234_wdfjwljet234_234wdfoijsdfmmnxpi492 is used to test objects for auto-vivifying attributes. If the test succeeds (e.g., the Box class), the new attribute is left on the object.

• _fields is used to test if an object appears to be a namedtuple. The comment asserts that “[i]t is possible to craft an object that passes this check and isn't a namedtuple, but there is only a minuscule chance of this happening unintentionally.” I don’t think that’s true; any object that auto-vivifies attributes will pass the check.

In my view, a library designed for debugging output (which rich is quite good at) should do its best to not modify the objects it is displaying, and if it does modify them, to be as obvious as practical about where the modifications came from.

I would suggest:

1. Because the sentinel awehoi234_wdfjwljet234_234wdfoijsdfmmnxpi492 is controlled by rich, change it to something that makes its provenance clear, say _rich_fake_attribute_test.

2. Remove the sentinel attribute if it’s successfully created, e.g. with delattr().

3. Test for the presence of _fields in a way that avoids false positives on auto-vivifying objects, e.g. with __getattribute__() instead of getattr().

Thanks for rich, it’s been very helpful.

Platform

Click to expand

Virtual machine accessed by SSH:

$ cat /etc/os-release
PRETTY_NAME="Debian GNU/Linux 13 (trixie)"
NAME="Debian GNU/Linux"
VERSION_ID="13"
VERSION="13 (trixie)"
VERSION_CODENAME=trixie
DEBIAN_VERSION_FULL=13.4
ID=debian
HOME_URL="https://www.debian.org/"
SUPPORT_URL="https://www.debian.org/support"
BUG_REPORT_URL="https://bugs.debian.org/"

Terminal is iTerm2 3.6.11 on Mac.

$ python -m rich.diagnose
╭─────────────────────── <class 'rich.console.Console'> ───────────────────────╮
│ A high level console interface.                                              │
│                                                                              │
│ ╭──────────────────────────────────────────────────────────────────────────╮ │
│ │ <console width=80 ColorSystem.EIGHT_BIT>                                 │ │
│ ╰──────────────────────────────────────────────────────────────────────────╯ │
│                                                                              │
│     color_system = '256'                                                     │
│         encoding = 'utf-8'                                                   │
│             file = <_io.TextIOWrapper name='<stdout>' mode='w'               │
│                    encoding='utf-8'>                                         │
│           height = 25                                                        │
│    is_alt_screen = False                                                     │
│ is_dumb_terminal = False                                                     │
│   is_interactive = True                                                      │
│       is_jupyter = False                                                     │
│      is_terminal = True                                                      │
│   legacy_windows = False                                                     │
│         no_color = False                                                     │
│          options = ConsoleOptions(                                           │
│                        size=ConsoleDimensions(width=80, height=25),          │
│                        legacy_windows=False,                                 │
│                        min_width=1,                                          │
│                        max_width=80,                                         │
│                        is_terminal=True,                                     │
│                        encoding='utf-8',                                     │
│                        max_height=25,                                        │
│                        justify=None,                                         │
│                        overflow=None,                                        │
│                        no_wrap=False,                                        │
│                        highlight=None,                                       │
│                        markup=None,                                          │
│                        height=None                                           │
│                    )                                                         │
│            quiet = False                                                     │
│           record = False                                                     │
│         safe_box = True                                                      │
│             size = ConsoleDimensions(width=80, height=25)                    │
│        soft_wrap = False                                                     │
│           stderr = False                                                     │
│            style = None                                                      │
│         tab_size = 8                                                         │
│            width = 80                                                        │
╰──────────────────────────────────────────────────────────────────────────────╯
╭─── <class 'rich._windows.WindowsConsoleFeatures'> ────╮
│ Windows features available.                           │
│                                                       │
│ ╭───────────────────────────────────────────────────╮ │
│ │ WindowsConsoleFeatures(vt=False, truecolor=False) │ │
│ ╰───────────────────────────────────────────────────╯ │
│                                                       │
│ truecolor = False                                     │
│        vt = False                                     │
╰───────────────────────────────────────────────────────╯
╭────── Environment Variables ───────╮
│ {                                  │
│     'CLICOLOR': None,              │
│     'COLORTERM': None,             │
│     'COLUMNS': None,               │
│     'JPY_PARENT_PID': None,        │
│     'JUPYTER_COLUMNS': None,       │
│     'JUPYTER_LINES': None,         │
│     'LINES': None,                 │
│     'NO_COLOR': None,              │
│     'TERM_PROGRAM': None,          │
│     'TERM': 'xterm-256color',      │
│     'TTY_COMPATIBLE': None,        │
│     'TTY_INTERACTIVE': None,       │
│     'VSCODE_VERBOSE_LOGGING': None │
│ }                                  │
╰────────────────────────────────────╯
platform="Linux"
$ pip freeze | fgrep rich
rich==15.0.0

[jeevesh47]

Hi! I investigated this issue and prepared a fix along with a regression test.

The issue occurs because Rich probes objects for auto-vivifying attributes using hasattr() with a temporary attribute name. For objects implementing __getattr__, this probe creates the temporary attribute and leaves it on the object after inspection.

My change removes the temporary probe attribute after the check, and I added a regression test to verify that pretty_repr() no longer leaves the probe attribute behind. I also verified that the existing tests/test_pretty.py test suite still passes.

However, when I try to open a pull request from my fork, GitHub shows "Pull request restricted", so I can't submit the PR. Is there an alternative contribution process, or is pull request creation currently limited to collaborators?

[apoorvdarshan]

Hi! I'd like to work on this. Per the AI policy I'm seeking maintainer approval for the approach before opening a PR (which would disclose AI assistance — Claude Code — with the work reviewed and owned by me).

I reproduced all three problems on current master:

1. pretty_repr() leaves awehoi234_wdfjwljet234_234wdfoijsdfmmnxpi492 in the __dict__ of auto-vivifying objects (e.g. Box(default_box=True)).
2. _is_namedtuple() similarly vivifies _fields onto such objects (the second junk attribute you found).
3. A tuple subclass with an auto-vivifying __getattr__ returning a tuple false-positives as a namedtuple.

Proposed fix (minimal diff, verified locally — full test_pretty.py suite passes):

• In traverse(): after the hasattr(obj, <probe>) check succeeds, best-effort delattr(obj, <probe>) in a try/except, so the probe attribute is not left on objects that auto-vivify it. (Fixes 1.)
• In _is_namedtuple(): look up _fields on type(obj) instead of the instance. Real namedtuples define _fields on the class, so detection is unchanged, but instance-level __getattr__ is never triggered — no mutation and no false positive. (Fixes 2 and 3.)

I'd keep the probe attribute name as-is to minimize the diff, but happy to also rename it to something provenance-clear (e.g. _rich_fake_attribute_probe) if preferred — with the delattr cleanup the name only matters in the rare case where cleanup fails.

Would this approach be acceptable?