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Diffstat (limited to 'Doc/library/sys.rst')
| -rw-r--r-- | Doc/library/sys.rst | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst index 5bde687..817c3f1 100644 --- a/Doc/library/sys.rst +++ b/Doc/library/sys.rst @@ -1514,13 +1514,21 @@ always available. * *err_msg*: Error message, can be ``None``. * *object*: Object causing the exception, can be ``None``. - :func:`sys.unraisablehook` can be overridden to control how unraisable - exceptions are handled. - The default hook formats *err_msg* and *object* as: ``f'{err_msg}: {object!r}'``; use "Exception ignored in" error message if *err_msg* is ``None``. + :func:`sys.unraisablehook` can be overridden to control how unraisable + exceptions are handled. + + Storing *exc_value* using a custom hook can create a reference cycle. It + should be cleared explicitly to break the reference cycle when the + exception is no longer needed. + + Storing *object* using a custom hook can resurrect it if it is set to an + object which is being finalized. Avoid storing *object* after the custom + hook completes to avoid resurrecting objects. + See also :func:`excepthook` which handles uncaught exceptions. .. versionadded:: 3.8 |