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bpo-26389: Allow passing an exception object in the traceback module (GH-22610)

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The format_exception(), format_exception_only(), and
print_exception() functions can now take an exception object as a positional-only argument.

Co-Authored-By: Matthias Bussonnier <bussonniermatthias@gmail.com>
This commit is contained in:
Zackery Spytz 2020-11-05 15:18:44 -07:00 • committed by GitHub
parent dc42af8fd1
commit 91e93794d5
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5 changed files with 97 additions and 24 deletions
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36
Lib/traceback.py
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@ -84,7 +84,19 @@ _context_message = (
"another exception occurred:\n\n")
def print_exception(etype, value, tb, limit=None, file=None, chain=True):
_sentinel = object()
def _parse_value_tb(exc, value, tb):
if (value is _sentinel) != (tb is _sentinel):
raise ValueError("Both or neither of value and tb must be given")
if value is tb is _sentinel:
return exc, exc.__traceback__
return value, tb
def print_exception(exc, /, value=_sentinel, tb=_sentinel, limit=None, \
file=None, chain=True):
"""Print exception up to 'limit' stack trace entries from 'tb' to 'file'.
This differs from print_tb() in the following ways: (1) if
@ -95,9 +107,7 @@ def print_exception(etype, value, tb, limit=None, file=None, chain=True):
occurred with a caret on the next line indicating the approximate
position of the error.
"""
# format_exception has ignored etype for some time, and code such as cgitb
# passes in bogus values as a result. For compatibility with such code we
# ignore it here (rather than in the new TracebackException API).
value, tb = _parse_value_tb(exc, value, tb)
if file is None:
file = sys.stderr
for line in TracebackException(
@ -105,7 +115,8 @@ def print_exception(etype, value, tb, limit=None, file=None, chain=True):
print(line, file=file, end="")
def format_exception(etype, value, tb, limit=None, chain=True):
def format_exception(exc, /, value=_sentinel, tb=_sentinel, limit=None, \
chain=True):
"""Format a stack trace and the exception information.
The arguments have the same meaning as the corresponding arguments
@ -114,19 +125,15 @@ def format_exception(etype, value, tb, limit=None, chain=True):
these lines are concatenated and printed, exactly the same text is
printed as does print_exception().
"""
# format_exception has ignored etype for some time, and code such as cgitb
# passes in bogus values as a result. For compatibility with such code we
# ignore it here (rather than in the new TracebackException API).
value, tb = _parse_value_tb(exc, value, tb)
return list(TracebackException(
type(value), value, tb, limit=limit).format(chain=chain))
def format_exception_only(etype, value):
def format_exception_only(exc, /, value=_sentinel):
"""Format the exception part of a traceback.
The arguments are the exception type and value such as given by
sys.last_type and sys.last_value. The return value is a list of
strings, each ending in a newline.
The return value is a list of strings, each ending in a newline.
Normally, the list contains a single string; however, for
SyntaxError exceptions, it contains several lines that (when
@ -137,7 +144,10 @@ def format_exception_only(etype, value):
string in the list.
"""
return list(TracebackException(etype, value, None).format_exception_only())
if value is _sentinel:
value = exc
return list(TracebackException(
type(value), value, None).format_exception_only())
# -- not official API but folk probably use these two functions.