[Python-checkins] bpo-34536: raise error for invalid _missing_ results (GH-9147) (GH-9978)
Ethan Furman
webhook-mailer at python.org
Fri Oct 19 19:49:33 EDT 2018
https://github.com/python/cpython/commit/0f2fc8bee0b435ee2934751264196db30d16ed8a
commit: 0f2fc8bee0b435ee2934751264196db30d16ed8a
branch: 3.7
author: Victor Stinner <vstinner at redhat.com>
committer: Ethan Furman <ethan at stoneleaf.us>
date: 2018-10-19T16:49:30-07:00
summary:
bpo-34536: raise error for invalid _missing_ results (GH-9147) (GH-9978)
* raise exception if _missing_ returns None or invalid type
files:
A Misc/NEWS.d/next/Library/2018-09-11-15-49-09.bpo-34536.3IPIH5.rst
M Lib/enum.py
M Lib/test/test_enum.py
diff --git a/Lib/enum.py b/Lib/enum.py
index 87f36911144a..e5a80cd609d4 100644
--- a/Lib/enum.py
+++ b/Lib/enum.py
@@ -540,7 +540,25 @@ def __new__(cls, value):
if member._value_ == value:
return member
# still not found -- try _missing_ hook
- return cls._missing_(value)
+ try:
+ exc = None
+ result = cls._missing_(value)
+ except Exception as e:
+ exc = e
+ result = None
+ if isinstance(result, cls):
+ return result
+ else:
+ ve_exc = ValueError("%r is not a valid %s" % (value, cls.__name__))
+ if result is None and exc is None:
+ raise ve_exc
+ elif exc is None:
+ exc = TypeError(
+ 'error in %s._missing_: returned %r instead of None or a valid member'
+ % (cls.__name__, result)
+ )
+ exc.__context__ = ve_exc
+ raise exc
def _generate_next_value_(name, start, count, last_values):
for last_value in reversed(last_values):
diff --git a/Lib/test/test_enum.py b/Lib/test/test_enum.py
index 60eabbe3d487..b221045328db 100644
--- a/Lib/test/test_enum.py
+++ b/Lib/test/test_enum.py
@@ -1717,6 +1717,38 @@ class Dupes(Enum):
third = auto()
self.assertEqual([Dupes.first, Dupes.second, Dupes.third], list(Dupes))
+ def test_missing(self):
+ class Color(Enum):
+ red = 1
+ green = 2
+ blue = 3
+ @classmethod
+ def _missing_(cls, item):
+ if item == 'three':
+ return cls.blue
+ elif item == 'bad return':
+ # trigger internal error
+ return 5
+ elif item == 'error out':
+ raise ZeroDivisionError
+ else:
+ # trigger not found
+ return None
+ self.assertIs(Color('three'), Color.blue)
+ self.assertRaises(ValueError, Color, 7)
+ try:
+ Color('bad return')
+ except TypeError as exc:
+ self.assertTrue(isinstance(exc.__context__, ValueError))
+ else:
+ raise Exception('Exception not raised.')
+ try:
+ Color('error out')
+ except ZeroDivisionError as exc:
+ self.assertTrue(isinstance(exc.__context__, ValueError))
+ else:
+ raise Exception('Exception not raised.')
+
def test_multiple_mixin(self):
class MaxMixin:
@classproperty
diff --git a/Misc/NEWS.d/next/Library/2018-09-11-15-49-09.bpo-34536.3IPIH5.rst b/Misc/NEWS.d/next/Library/2018-09-11-15-49-09.bpo-34536.3IPIH5.rst
new file mode 100644
index 000000000000..be45eb57cad5
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-09-11-15-49-09.bpo-34536.3IPIH5.rst
@@ -0,0 +1,2 @@
+`Enum._missing_`: raise `ValueError` if None returned and `TypeError` if
+non-member is returned.
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