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gh-112328: [Enum] Make some private attributes public. (GH-112514) 

* [Enum] Make some private attributes public.

- ``_EnumDict`` --> ``EnumDict``
- ``EnumDict._member_names`` --> ``EnumDict.member_names``
- ``Enum._add_alias_``
- ``Enum._add_value_alias_``

---------

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
Co-authored-by: Nikita Sobolev <mail@sobolevn.me>
This commit is contained in:
Ethan Furman 2023-12-05 08:27:36 -08:00 committed by GitHub
parent 563ccded6e
commit de6bca9564
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5 changed files with 301 additions and 117 deletions
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67
Doc/howto/enum.rst
View File

@ -868,7 +868,7 @@ Others
While :class:`IntEnum` is part of the :mod:`enum` module, it would be very
simple to implement independently::
class IntEnum(int, Enum):
class IntEnum(int, ReprEnum): # or Enum instead of ReprEnum
pass
This demonstrates how similar derived enumerations can be defined; for example
@ -876,8 +876,8 @@ a :class:`FloatEnum` that mixes in :class:`float` instead of :class:`int`.
Some rules:
1. When subclassing :class:`Enum`, mix-in types must appear before
:class:`Enum` itself in the sequence of bases, as in the :class:`IntEnum`
1. When subclassing :class:`Enum`, mix-in types must appear before the
:class:`Enum` class itself in the sequence of bases, as in the :class:`IntEnum`
example above.
2. Mix-in types must be subclassable. For example, :class:`bool` and
:class:`range` are not subclassable and will throw an error during Enum
@ -961,30 +961,34 @@ all the members are created it is no longer used.
Supported ``_sunder_`` names
""""""""""""""""""""""""""""
- ``_name_`` -- name of the member
- ``_value_`` -- value of the member; can be set / modified in ``__new__``
- :attr:`~Enum._name_` -- name of the member
- :attr:`~Enum._value_` -- value of the member; can be set in ``__new__``
- :meth:`~Enum._missing_` -- a lookup function used when a value is not found;
may be overridden
- :attr:`~Enum._ignore_` -- a list of names, either as a :class:`list` or a
:class:`str`, that will not be transformed into members, and will be removed
from the final class
- :meth:`~Enum._generate_next_value_` -- used to get an appropriate value for
an enum member; may be overridden
- :meth:`~Enum._add_alias_` -- adds a new name as an alias to an existing
member.
- :meth:`~Enum._add_value_alias_` -- adds a new value as an alias to an
existing member. See `MultiValueEnum`_ for an example.
- ``_missing_`` -- a lookup function used when a value is not found; may be
overridden
- ``_ignore_`` -- a list of names, either as a :class:`list` or a :class:`str`,
that will not be transformed into members, and will be removed from the final
class
- ``_order_`` -- used in Python 2/3 code to ensure member order is consistent
(class attribute, removed during class creation)
- ``_generate_next_value_`` -- used by the `Functional API`_ and by
:class:`auto` to get an appropriate value for an enum member; may be
overridden
.. note::
.. note::
For standard :class:`Enum` classes the next value chosen is the highest
value seen incremented by one.
For standard :class:`Enum` classes the next value chosen is the last value seen
incremented by one.
For :class:`Flag` classes the next value chosen will be the next highest
power-of-two.
For :class:`Flag` classes the next value chosen will be the next highest
power-of-two, regardless of the last value seen.
.. versionchanged:: 3.13
Prior versions would use the last seen value instead of the highest value.
.. versionadded:: 3.6 ``_missing_``, ``_order_``, ``_generate_next_value_``
.. versionadded:: 3.7 ``_ignore_``
.. versionadded:: 3.13 ``_add_alias_``, ``_add_value_alias_``
To help keep Python 2 / Python 3 code in sync an :attr:`_order_` attribute can
be provided. It will be checked against the actual order of the enumeration
@ -1447,6 +1451,29 @@ alias::
disallowing aliases, the :func:`unique` decorator can be used instead.
MultiValueEnum
^^^^^^^^^^^^^^^^^
Supports having more than one value per member::
>>> class MultiValueEnum(Enum):
... def __new__(cls, value, *values):
... self = object.__new__(cls)
... self._value_ = value
... for v in values:
... self._add_value_alias_(v)
... return self
...
>>> class DType(MultiValueEnum):
... float32 = 'f', 8
... double64 = 'd', 9
...
>>> DType('f')
<DType.float32: 'f'>
>>> DType(9)
<DType.double64: 'd'>
Planet
^^^^^^

60
Doc/library/enum.rst
View File

@ -235,6 +235,10 @@ Data Types
>>> len(Color)
3
.. attribute:: EnumType.__members__
Returns a mapping of every enum name to its member, including aliases
.. method:: EnumType.__reversed__(cls)
Returns each member in *cls* in reverse definition order::
@ -242,9 +246,19 @@ Data Types
>>> list(reversed(Color))
[<Color.BLUE: 3>, <Color.GREEN: 2>, <Color.RED: 1>]
.. method:: EnumType._add_alias_
Adds a new name as an alias to an existing member. Raises a
:exc:`NameError` if the name is already assigned to a different member.
.. method:: EnumType._add_value_alias_
Adds a new value as an alias to an existing member. Raises a
:exc:`ValueError` if the value is already linked with a different member.
.. versionadded:: 3.11
Before 3.11 ``enum`` used ``EnumMeta`` type, which is kept as an alias.
Before 3.11 ``EnumType`` was called ``EnumMeta``, which is still available as an alias.
.. class:: Enum
@ -323,7 +337,7 @@ Data Types
>>> PowersOfThree.SECOND.value
9
.. method:: Enum.__init_subclass__(cls, **kwds)
.. method:: Enum.__init_subclass__(cls, \**kwds)
A *classmethod* that is used to further configure subsequent subclasses.
By default, does nothing.
@ -549,7 +563,7 @@ Data Types
.. method:: __invert__(self):
Returns all the flags in *type(self)* that are not in self::
Returns all the flags in *type(self)* that are not in *self*::
>>> ~white
<Color: 0>
@ -769,37 +783,41 @@ Supported ``__dunder__`` names
:attr:`~EnumType.__members__` is a read-only ordered mapping of ``member_name``:``member``
items. It is only available on the class.
:meth:`~object.__new__`, if specified, must create and return the enum members; it is
also a very good idea to set the member's :attr:`!_value_` appropriately. Once
all the members are created it is no longer used.
:meth:`~object.__new__`, if specified, must create and return the enum members;
it is also a very good idea to set the member's :attr:`!_value_` appropriately.
Once all the members are created it is no longer used.
Supported ``_sunder_`` names
""""""""""""""""""""""""""""
- ``_name_`` -- name of the member
- ``_value_`` -- value of the member; can be set / modified in ``__new__``
- ``_missing_`` -- a lookup function used when a value is not found; may be
overridden
- ``_ignore_`` -- a list of names, either as a :class:`list` or a :class:`str`,
that will not be transformed into members, and will be removed from the final
class
- ``_order_`` -- used in Python 2/3 code to ensure member order is consistent
(class attribute, removed during class creation)
- ``_generate_next_value_`` -- used to get an appropriate value for an enum
member; may be overridden
- :meth:`~EnumType._add_alias_` -- adds a new name as an alias to an existing
member.
- :meth:`~EnumType._add_value_alias_` -- adds a new value as an alias to an
existing member.
- :attr:`~Enum._name_` -- name of the member
- :attr:`~Enum._value_` -- value of the member; can be set in ``__new__``
- :meth:`~Enum._missing_` -- a lookup function used when a value is not found;
may be overridden
- :attr:`~Enum._ignore_` -- a list of names, either as a :class:`list` or a
:class:`str`, that will not be transformed into members, and will be removed
from the final class
- :attr:`~Enum._order_` -- used in Python 2/3 code to ensure member order is
consistent (class attribute, removed during class creation)
- :meth:`~Enum._generate_next_value_` -- used to get an appropriate value for
an enum member; may be overridden
.. note::
For standard :class:`Enum` classes the next value chosen is the last value seen
incremented by one.
For standard :class:`Enum` classes the next value chosen is the highest
value seen incremented by one.
For :class:`Flag` classes the next value chosen will be the next highest
power-of-two, regardless of the last value seen.
power-of-two.
.. versionadded:: 3.6 ``_missing_``, ``_order_``, ``_generate_next_value_``
.. versionadded:: 3.7 ``_ignore_``
.. versionadded:: 3.13 ``_add_alias_``, ``_add_value_alias_``
---------------

203
Lib/enum.py
View File

@ -4,7 +4,7 @@ from types import MappingProxyType, DynamicClassAttribute
__all__ = [
'EnumType', 'EnumMeta',
'EnumType', 'EnumMeta', 'EnumDict',
'Enum', 'IntEnum', 'StrEnum', 'Flag', 'IntFlag', 'ReprEnum',
'auto', 'unique', 'property', 'verify', 'member', 'nonmember',
'FlagBoundary', 'STRICT', 'CONFORM', 'EJECT', 'KEEP',
@ -313,45 +313,8 @@ class _proto_member:
):
# no other instances found, record this member in _member_names_
enum_class._member_names_.append(member_name)
# if necessary, get redirect in place and then add it to _member_map_
found_descriptor = None
descriptor_type = None
class_type = None
for base in enum_class.__mro__[1:]:
attr = base.__dict__.get(member_name)
if attr is not None:
if isinstance(attr, (property, DynamicClassAttribute)):
found_descriptor = attr
class_type = base
descriptor_type = 'enum'
break
elif _is_descriptor(attr):
found_descriptor = attr
descriptor_type = descriptor_type or 'desc'
class_type = class_type or base
continue
else:
descriptor_type = 'attr'
class_type = base
if found_descriptor:
redirect = property()
redirect.member = enum_member
redirect.__set_name__(enum_class, member_name)
if descriptor_type in ('enum','desc'):
# earlier descriptor found; copy fget, fset, fdel to this one.
redirect.fget = getattr(found_descriptor, 'fget', None)
redirect._get = getattr(found_descriptor, '__get__', None)
redirect.fset = getattr(found_descriptor, 'fset', None)
redirect._set = getattr(found_descriptor, '__set__', None)
redirect.fdel = getattr(found_descriptor, 'fdel', None)
redirect._del = getattr(found_descriptor, '__delete__', None)
redirect._attr_type = descriptor_type
redirect._cls_type = class_type
setattr(enum_class, member_name, redirect)
else:
setattr(enum_class, member_name, enum_member)
# now add to _member_map_ (even aliases)
enum_class._member_map_[member_name] = enum_member
enum_class._add_member_(member_name, enum_member)
try:
# This may fail if value is not hashable. We can't add the value
# to the map, and by-value lookups for this value will be
@ -360,9 +323,10 @@ class _proto_member:
except TypeError:
# keep track of the value in a list so containment checks are quick
enum_class._unhashable_values_.append(value)
enum_class._unhashable_values_map_.setdefault(member_name, []).append(value)
class _EnumDict(dict):
class EnumDict(dict):
"""
Track enum member order and ensure member names are not reused.
@ -371,7 +335,7 @@ class _EnumDict(dict):
"""
def __init__(self):
super().__init__()
self._member_names = {} # use a dict to keep insertion order
self._member_names = {} # use a dict -- faster look-up than a list, and keeps insertion order since 3.7
self._last_values = []
self._ignore = []
self._auto_called = False
@ -393,6 +357,7 @@ class _EnumDict(dict):
'_order_',
'_generate_next_value_', '_numeric_repr_', '_missing_', '_ignore_',
'_iter_member_', '_iter_member_by_value_', '_iter_member_by_def_',
'_add_alias_', '_add_value_alias_',
):
raise ValueError(
'_sunder_ names, such as %r, are reserved for future Enum use'
@ -468,6 +433,10 @@ class _EnumDict(dict):
self._last_values.append(value)
super().__setitem__(key, value)
@property
def member_names(self):
return list(self._member_names)
def update(self, members, **more_members):
try:
for name in members.keys():
@ -478,6 +447,8 @@ class _EnumDict(dict):
for name, value in more_members.items():
self[name] = value
_EnumDict = EnumDict # keep private name for backwards compatibility
class EnumType(type):
"""
@ -489,7 +460,7 @@ class EnumType(type):
# check that previous enum members do not exist
metacls._check_for_existing_members_(cls, bases)
# create the namespace dict
enum_dict = _EnumDict()
enum_dict = EnumDict()
enum_dict._cls_name = cls
# inherit previous flags and _generate_next_value_ function
member_type, first_enum = metacls._get_mixins_(cls, bases)
@ -552,6 +523,7 @@ class EnumType(type):
classdict['_member_map_'] = {}
classdict['_value2member_map_'] = {}
classdict['_unhashable_values_'] = []
classdict['_unhashable_values_map_'] = {}
classdict['_member_type_'] = member_type
# now set the __repr__ for the value
classdict['_value_repr_'] = metacls._find_data_repr_(cls, bases)
@ -754,7 +726,10 @@ class EnumType(type):
"""
if isinstance(value, cls):
return True
return value in cls._value2member_map_ or value in cls._unhashable_values_
try:
return value in cls._value2member_map_
except TypeError:
return value in cls._unhashable_values_
def __delattr__(cls, attr):
# nicer error message when someone tries to delete an attribute
@ -1050,7 +1025,57 @@ class EnumType(type):
else:
use_args = True
return __new__, save_new, use_args
EnumMeta = EnumType
def _add_member_(cls, name, member):
# _value_ structures are not updated
if name in cls._member_map_:
if cls._member_map_[name] is not member:
raise NameError('%r is already bound: %r' % (name, cls._member_map_[name]))
return
#
# if necessary, get redirect in place and then add it to _member_map_
found_descriptor = None
descriptor_type = None
class_type = None
for base in cls.__mro__[1:]:
attr = base.__dict__.get(name)
if attr is not None:
if isinstance(attr, (property, DynamicClassAttribute)):
found_descriptor = attr
class_type = base
descriptor_type = 'enum'
break
elif _is_descriptor(attr):
found_descriptor = attr
descriptor_type = descriptor_type or 'desc'
class_type = class_type or base
continue
else:
descriptor_type = 'attr'
class_type = base
if found_descriptor:
redirect = property()
redirect.member = member
redirect.__set_name__(cls, name)
if descriptor_type in ('enum', 'desc'):
# earlier descriptor found; copy fget, fset, fdel to this one.
redirect.fget = getattr(found_descriptor, 'fget', None)
redirect._get = getattr(found_descriptor, '__get__', None)
redirect.fset = getattr(found_descriptor, 'fset', None)
redirect._set = getattr(found_descriptor, '__set__', None)
redirect.fdel = getattr(found_descriptor, 'fdel', None)
redirect._del = getattr(found_descriptor, '__delete__', None)
redirect._attr_type = descriptor_type
redirect._cls_type = class_type
setattr(cls, name, redirect)
else:
setattr(cls, name, member)
# now add to _member_map_ (even aliases)
cls._member_map_[name] = member
#
cls._member_map_[name] = member
EnumMeta = EnumType # keep EnumMeta name for backwards compatibility
class Enum(metaclass=EnumType):
@ -1116,9 +1141,9 @@ class Enum(metaclass=EnumType):
pass
except TypeError:
# not there, now do long search -- O(n) behavior
for member in cls._member_map_.values():
if member._value_ == value:
return member
for name, values in cls._unhashable_values_map_.items():
if value in values:
return cls[name]
# still not found -- verify that members exist, in-case somebody got here mistakenly
# (such as via super when trying to override __new__)
if not cls._member_map_:
@ -1159,6 +1184,33 @@ class Enum(metaclass=EnumType):
def __init__(self, *args, **kwds):
pass
def _add_alias_(self, name):
self.__class__._add_member_(name, self)
def _add_value_alias_(self, value):
cls = self.__class__
try:
if value in cls._value2member_map_:
if cls._value2member_map_[value] is not self:
raise ValueError('%r is already bound: %r' % (value, cls._value2member_map_[value]))
return
except TypeError:
# unhashable value, do long search
for m in cls._member_map_.values():
if m._value_ == value:
if m is not self:
raise ValueError('%r is already bound: %r' % (value, cls._value2member_map_[value]))
return
try:
# This may fail if value is not hashable. We can't add the value
# to the map, and by-value lookups for this value will be
# linear.
cls._value2member_map_.setdefault(value, self)
except TypeError:
# keep track of the value in a list so containment checks are quick
cls._unhashable_values_.append(value)
cls._unhashable_values_map_.setdefault(self.name, []).append(value)
@staticmethod
def _generate_next_value_(name, start, count, last_values):
"""
@ -1671,7 +1723,8 @@ def _simple_enum(etype=Enum, *, boundary=None, use_args=None):
body['_member_names_'] = member_names = []
body['_member_map_'] = member_map = {}
body['_value2member_map_'] = value2member_map = {}
body['_unhashable_values_'] = []
body['_unhashable_values_'] = unhashable_values = []
body['_unhashable_values_map_'] = {}
body['_member_type_'] = member_type = etype._member_type_
body['_value_repr_'] = etype._value_repr_
if issubclass(etype, Flag):
@ -1718,14 +1771,9 @@ def _simple_enum(etype=Enum, *, boundary=None, use_args=None):
for name, value in attrs.items():
if isinstance(value, auto) and auto.value is _auto_null:
value = gnv(name, 1, len(member_names), gnv_last_values)
if value in value2member_map:
if value in value2member_map or value in unhashable_values:
# an alias to an existing member
member = value2member_map[value]
redirect = property()
redirect.member = member
redirect.__set_name__(enum_class, name)
setattr(enum_class, name, redirect)
member_map[name] = member
enum_class(value)._add_alias_(name)
else:
# create the member
if use_args:
@ -1740,12 +1788,12 @@ def _simple_enum(etype=Enum, *, boundary=None, use_args=None):
member._name_ = name
member.__objclass__ = enum_class
member.__init__(value)
redirect = property()
redirect.member = member
redirect.__set_name__(enum_class, name)
setattr(enum_class, name, redirect)
member_map[name] = member
member._sort_order_ = len(member_names)
if name not in ('name', 'value'):
setattr(enum_class, name, member)
member_map[name] = member
else:
enum_class._add_member_(name, member)
value2member_map[value] = member
if _is_single_bit(value):
# not a multi-bit alias, record in _member_names_ and _flag_mask_
@ -1768,14 +1816,13 @@ def _simple_enum(etype=Enum, *, boundary=None, use_args=None):
if value.value is _auto_null:
value.value = gnv(name, 1, len(member_names), gnv_last_values)
value = value.value
if value in value2member_map:
try:
contained = value in value2member_map
except TypeError:
contained = value in unhashable_values
if contained:
# an alias to an existing member
member = value2member_map[value]
redirect = property()
redirect.member = member
redirect.__set_name__(enum_class, name)
setattr(enum_class, name, redirect)
member_map[name] = member
enum_class(value)._add_alias_(name)
else:
# create the member
if use_args:
@ -1791,14 +1838,22 @@ def _simple_enum(etype=Enum, *, boundary=None, use_args=None):
member.__objclass__ = enum_class
member.__init__(value)
member._sort_order_ = len(member_names)
redirect = property()
redirect.member = member
redirect.__set_name__(enum_class, name)
setattr(enum_class, name, redirect)
member_map[name] = member
value2member_map[value] = member
if name not in ('name', 'value'):
setattr(enum_class, name, member)
member_map[name] = member
else:
enum_class._add_member_(name, member)
member_names.append(name)
gnv_last_values.append(value)
try:
# This may fail if value is not hashable. We can't add the value
# to the map, and by-value lookups for this value will be
# linear.
enum_class._value2member_map_.setdefault(value, member)
except TypeError:
# keep track of the value in a list so containment checks are quick
enum_class._unhashable_values_.append(value)
enum_class._unhashable_values_map_.setdefault(name, []).append(value)
if '__new__' in body:
enum_class.__new_member__ = enum_class.__new__
enum_class.__new__ = Enum.__new__

86
Lib/test/test_enum.py
View File

@ -514,6 +514,7 @@ class _EnumTests:
self.assertFalse('first' in MainEnum)
val = MainEnum.dupe
self.assertIn(val, MainEnum)
self.assertNotIn(float('nan'), MainEnum)
#
class OtherEnum(Enum):
one = auto()
@ -3268,6 +3269,65 @@ class TestSpecial(unittest.TestCase):
member._value_ = Base(value)
return member
def test_extra_member_creation(self):
class IDEnumMeta(EnumMeta):
def __new__(metacls, cls, bases, classdict, **kwds):
# add new entries to classdict
for name in classdict.member_names:
classdict[f'{name}_DESC'] = f'-{classdict[name]}'
return super().__new__(metacls, cls, bases, classdict, **kwds)
class IDEnum(StrEnum, metaclass=IDEnumMeta):
pass
class MyEnum(IDEnum):
ID = 'id'
NAME = 'name'
self.assertEqual(list(MyEnum), [MyEnum.ID, MyEnum.NAME, MyEnum.ID_DESC, MyEnum.NAME_DESC])
def test_add_alias(self):
class mixin:
@property
def ORG(self):
return 'huh'
class Color(mixin, Enum):
RED = 1
GREEN = 2
BLUE = 3
Color.RED._add_alias_('ROJO')
self.assertIs(Color.RED, Color['ROJO'])
self.assertIs(Color.RED, Color.ROJO)
Color.BLUE._add_alias_('ORG')
self.assertIs(Color.BLUE, Color['ORG'])
self.assertIs(Color.BLUE, Color.ORG)
self.assertEqual(Color.RED.ORG, 'huh')
self.assertEqual(Color.GREEN.ORG, 'huh')
self.assertEqual(Color.BLUE.ORG, 'huh')
self.assertEqual(Color.ORG.ORG, 'huh')
def test_add_value_alias_after_creation(self):
class Color(Enum):
RED = 1
GREEN = 2
BLUE = 3
Color.RED._add_value_alias_(5)
self.assertIs(Color.RED, Color(5))
def test_add_value_alias_during_creation(self):
class Types(Enum):
Unknown = 0,
Source = 1, 'src'
NetList = 2, 'nl'
def __new__(cls, int_value, *value_aliases):
member = object.__new__(cls)
member._value_ = int_value
for alias in value_aliases:
member._add_value_alias_(alias)
return member
self.assertIs(Types(0), Types.Unknown)
self.assertIs(Types(1), Types.Source)
self.assertIs(Types('src'), Types.Source)
self.assertIs(Types(2), Types.NetList)
self.assertIs(Types('nl'), Types.NetList)
class TestOrder(unittest.TestCase):
"test usage of the `_order_` attribute"
@ -4941,12 +5001,14 @@ class TestStdLib(unittest.TestCase):
@bltns.property
def zeroth(self):
return 'zeroed %s' % self.name
self.assertTrue(_test_simple_enum(CheckedColor, SimpleColor) is None)
_test_simple_enum(CheckedColor, SimpleColor)
SimpleColor.MAGENTA._value_ = 9
self.assertRaisesRegex(
TypeError, "enum mismatch",
_test_simple_enum, CheckedColor, SimpleColor,
)
#
#
class CheckedMissing(IntFlag, boundary=KEEP):
SIXTY_FOUR = 64
ONE_TWENTY_EIGHT = 128
@ -4963,8 +5025,28 @@ class TestStdLib(unittest.TestCase):
ALL = 2048 + 128 + 64 + 12
M = Missing
self.assertEqual(list(CheckedMissing), [M.SIXTY_FOUR, M.ONE_TWENTY_EIGHT, M.TWENTY_FORTY_EIGHT])
#
_test_simple_enum(CheckedMissing, Missing)
#
#
class CheckedUnhashable(Enum):
ONE = dict()
TWO = set()
name = 'python'
self.assertIn(dict(), CheckedUnhashable)
self.assertIn('python', CheckedUnhashable)
self.assertEqual(CheckedUnhashable.name.value, 'python')
self.assertEqual(CheckedUnhashable.name.name, 'name')
#
@_simple_enum()
class Unhashable:
ONE = dict()
TWO = set()
name = 'python'
self.assertIn(dict(), Unhashable)
self.assertIn('python', Unhashable)
self.assertEqual(Unhashable.name.value, 'python')
self.assertEqual(Unhashable.name.name, 'name')
_test_simple_enum(Unhashable, Unhashable)
class MiscTestCase(unittest.TestCase):

2
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[Enum] Make ``EnumDict``, ``EnumDict.member_names``,
``EnumType._add_alias_`` and ``EnumType._add_value_alias_`` public.