From 7212fbe23573b20673d7cc14818079b5c550b64d Mon Sep 17 00:00:00 2001 From: Ethan Onstott Date: Tue, 28 Apr 2020 13:20:55 -0400 Subject: [PATCH] bpo-40025: Require _generate_next_value_ to be defined before members (GH-19098) require `_generate_next_value_` to be defined before members (cherry picked from commit d9a43e20facdf4ad10186f820601c6580e1baa80) Co-authored-by: Ethan Onstott --- Doc/library/enum.rst | 4 ++++ Lib/enum.py | 5 +++++ Lib/test/test_enum.py | 10 ++++++++++ Misc/ACKS | 1 + .../Library/2020-03-21-05-26-38.bpo-40025.DTLtyq.rst | 1 + 5 files changed, 21 insertions(+) create mode 100644 Misc/NEWS.d/next/Library/2020-03-21-05-26-38.bpo-40025.DTLtyq.rst diff --git a/Doc/library/enum.rst b/Doc/library/enum.rst index 38221199dcdb74..e340f3ba643e71 100644 --- a/Doc/library/enum.rst +++ b/Doc/library/enum.rst @@ -273,6 +273,10 @@ overridden:: the next :class:`int` in sequence with the last :class:`int` provided, but the way it does this is an implementation detail and may change. +.. note:: + + The :meth:`_generate_next_value_` method must be defined before any members. + Iteration --------- diff --git a/Lib/enum.py b/Lib/enum.py index d0b03b4aa56ce4..83e6410107ce0b 100644 --- a/Lib/enum.py +++ b/Lib/enum.py @@ -66,6 +66,7 @@ def __init__(self): self._member_names = [] self._last_values = [] self._ignore = [] + self._auto_called = False def __setitem__(self, key, value): """Changes anything not dundered or not a descriptor. @@ -83,6 +84,9 @@ def __setitem__(self, key, value): ): raise ValueError('_names_ are reserved for future Enum use') if key == '_generate_next_value_': + # check if members already defined as auto() + if self._auto_called: + raise TypeError("_generate_next_value_ must be defined before members") setattr(self, '_generate_next_value', value) elif key == '_ignore_': if isinstance(value, str): @@ -106,6 +110,7 @@ def __setitem__(self, key, value): # enum overwriting a descriptor? raise TypeError('%r already defined as: %r' % (key, self[key])) if isinstance(value, auto): + self._auto_called = True if value.value == _auto_null: value.value = self._generate_next_value(key, 1, len(self._member_names), self._last_values[:]) value = value.value diff --git a/Lib/test/test_enum.py b/Lib/test/test_enum.py index 29a429ccd998f2..d9260f4cb475f7 100644 --- a/Lib/test/test_enum.py +++ b/Lib/test/test_enum.py @@ -1710,6 +1710,16 @@ class Color(Enum): self.assertEqual(Color.blue.value, 2) self.assertEqual(Color.green.value, 3) + def test_auto_order(self): + with self.assertRaises(TypeError): + class Color(Enum): + red = auto() + green = auto() + blue = auto() + def _generate_next_value_(name, start, count, last): + return name + + def test_duplicate_auto(self): class Dupes(Enum): first = primero = auto() diff --git a/Misc/ACKS b/Misc/ACKS index 27ef39754afd90..3dcf9ae2bce277 100644 --- a/Misc/ACKS +++ b/Misc/ACKS @@ -1184,6 +1184,7 @@ Adam Olsen Bryan Olson Grant Olson Koray Oner +Ethan Onstott Piet van Oostrum Tomas Oppelstrup Jason Orendorff diff --git a/Misc/NEWS.d/next/Library/2020-03-21-05-26-38.bpo-40025.DTLtyq.rst b/Misc/NEWS.d/next/Library/2020-03-21-05-26-38.bpo-40025.DTLtyq.rst new file mode 100644 index 00000000000000..7b699de4e0726f --- /dev/null +++ b/Misc/NEWS.d/next/Library/2020-03-21-05-26-38.bpo-40025.DTLtyq.rst @@ -0,0 +1 @@ +Raise TypeError when _generate_next_value_ is defined after members. Patch by Ethan Onstott. \ No newline at end of file