8000 bpo-40025: Require _generate_next_value_ to be defined before members… · python/cpython@d9a43e2 · GitHub
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bpo-40025: Require _generate_next_value_ to be defined before members (GH-19098)
require `_generate_next_value_` to be defined before members
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‎Doc/library/enum.rst

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@@ -273,6 +273,10 @@ overridden::
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the next :class:`int` in sequence with the last :class:`int` provided, but
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the way it does this is an implementation detail and may change.
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.. note::
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The :meth:`_generate_next_value_` method must be defined before any members.
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Iteration
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---------
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‎Lib/enum.py

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@@ -60,6 +60,7 @@ def __init__(self):
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self._member_names = []
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self._last_values = []
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self._ignore = []
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self._auto_called = False
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def __setitem__(self, key, value):
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"""Changes anything not dundered or not a descriptor.
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):
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raise ValueError('_names_ are reserved for future Enum use')
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if key == '_generate_next_value_':
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# check if members already defined as auto()
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if self._auto_called:
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raise TypeError("_generate_next_value_ must be defined before members")
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setattr(self, '_generate_next_value', value)
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elif key == '_ignore_':
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if isinstance(value, str):
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# enum overwriting a descriptor?
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raise TypeError('%r already defined as: %r' % (key, self[key]))
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if isinstance(value, auto):
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self._auto_called = True
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if value.value == _auto_null:
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value.value = self._generate_next_value(key, 1, len(self._member_names), self._last_values[:])
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value = value.value

‎Lib/test/test_enum.py

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@@ -1751,6 +1751,16 @@ class Color(Enum):
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self.assertEqual(Color.blue.value, 2)
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self.assertEqual(Color.green.value, 3)
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def test_auto_order(self):
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with self.assertRaises(TypeError):
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class Color(Enum):
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red = auto()
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green = auto()
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blue = auto()
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def _generate_next_value_(name, start, count, last):
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return name
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def test_duplicate_auto(self):
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class Dupes(Enum):
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first = primero = auto()

‎Misc/ACKS

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@@ -1240,6 +1240,7 @@ Bryan Olson
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Grant Olson
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Furkan Onder
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Koray Oner
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Ethan Onstott
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Piet van Oostrum
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Tomas Oppelstrup
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Jason Orendorff

‎Misc/NEWS.d/next/Library/2020-03-21-05-26-38.bpo-40025.DTLtyq.rst

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Raise TypeError when _generate_next_value_ is defined after members. Patch by Ethan Onstott.

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