bpo-43024: improve signature (in help, etc) for functions taking sent… (GH-24331) (GH-26773)
…inel defaults
(cherry picked from commit f73377d57c5272390de63cccc3c292c44689310a)
Co-authored-by: Irit Katriel <1055913+iritkatriel@users.noreply.github.com>
diff --git a/Lib/test/test_traceback.py b/Lib/test/test_traceback.py
index 5bd969d..dd94590 100644
--- a/Lib/test/test_traceback.py
+++ b/Lib/test/test_traceback.py
@@ -4,6 +4,7 @@
from io import StringIO
import linecache
import sys
+import inspect
import unittest
import re
from test import support
@@ -255,6 +256,21 @@ def test_exception_is_None(self):
self.assertEqual(
traceback.format_exception_only(None, None), [NONE_EXC_STRING])
+ def test_signatures(self):
+ self.assertEqual(
+ str(inspect.signature(traceback.print_exception)),
+ ('(exc, /, value=<implicit>, tb=<implicit>, '
+ 'limit=None, file=None, chain=True)'))
+
+ self.assertEqual(
+ str(inspect.signature(traceback.format_exception)),
+ ('(exc, /, value=<implicit>, tb=<implicit>, limit=None, '
+ 'chain=True)'))
+
+ self.assertEqual(
+ str(inspect.signature(traceback.format_exception_only)),
+ '(exc, /, value=<implicit>)')
+
class TracebackFormatTests(unittest.TestCase):
diff --git a/Lib/traceback.py b/Lib/traceback.py
index 8f908dd..7a7cca1 100644
--- a/Lib/traceback.py
+++ b/Lib/traceback.py
@@ -84,8 +84,11 @@ def extract_tb(tb, limit=None):
"another exception occurred:\n\n")
-_sentinel = object()
+class _Sentinel:
+ def __repr__(self):
+ return "<implicit>"
+_sentinel = _Sentinel()
def _parse_value_tb(exc, value, tb):
if (value is _sentinel) != (tb is _sentinel):