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Closes issue 17947. Adds PEP-0435 (Adding an Enum type to the Python standard library).

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:mod:`enum` --- Support for enumerations
========================================
.. module:: enum
.. :synopsis: enumerations are sets of symbolic names bound to unique, constant
values.
.. :moduleauthor:: Ethan Furman <ethan@stoneleaf.us>
.. :sectionauthor:: Barry Warsaw <barry@python.org>,
.. :sectionauthor:: Eli Bendersky <eliben@gmail.com>,
.. :sectionauthor:: Ethan Furman <ethan@stoneleaf.us>
**Source code:** :source:`Lib/enum.py`
----------------
An enumeration is a set of symbolic names (members) bound to unique, constant
values. Within an enumeration, the members can be compared by identity, and
the enumeration itself can be iterated over.
This module defines two enumeration classes that can be used to define unique
sets of names and values: :class:`Enum` and :class:`IntEnum`.
Creating an Enum
----------------
Enumerations are created using the :keyword:`class` syntax, which makes them
easy to read and write. An alternative creation method is described in
`Functional API`_. To define an enumeration, subclass :class:`Enum` as
follows::
>>> from enum import Enum
>>> class Color(Enum):
... red = 1
... green = 2
... blue = 3
**A note on nomenclature**: we call :class:`Color` an *enumeration* (or *enum*)
and :attr:`Color.red`, :attr:`Color.green` are *enumeration members* (or
*enum members*). Enumeration members also have *values* (the value of
:attr:`Color.red` is ``1``, etc.)
Enumeration members have human readable string representations::
>>> print(Color.red)
Color.red
...while their ``repr`` has more information::
>>> print(repr(Color.red))
<Color.red: 1>
The *type* of an enumeration member is the enumeration it belongs to::
>>> type(Color.red)
<enum 'Color'>
>>> isinstance(Color.green, Color)
True
>>>
Enum members also have a property that contains just their item name::
>>> print(Color.red.name)
red
Enumerations support iteration, in definition order::
>>> class Shake(Enum):
... vanilla = 7
... chocolate = 4
... cookies = 9
... mint = 3
...
>>> for shake in Shake:
... print(shake)
...
Shake.vanilla
Shake.chocolate
Shake.cookies
Shake.mint
Enumeration members are hashable, so they can be used in dictionaries and sets::
>>> apples = {}
>>> apples[Color.red] = 'red delicious'
>>> apples[Color.green] = 'granny smith'
>>> apples == {Color.red: 'red delicious', Color.green: 'granny smith'}
True
Programmatic access to enumeration members
------------------------------------------
Sometimes it's useful to access members in enumerations programmatically (i.e.
situations where ``Color.red`` won't do because the exact color is not known
at program-writing time). ``Enum`` allows such access::
>>> Color(1)
<Color.red: 1>
>>> Color(3)
<Color.blue: 3>
If you want to access enum members by *name*, use item access::
>>> Color['red']
<Color.red: 1>
>>> Color['green']
<Color.green: 2>
Duplicating enum members and values
-----------------------------------
Having two enum members with the same name is invalid::
>>> class Shape(Enum):
... square = 2
... square = 3
...
Traceback (most recent call last):
...
TypeError: Attempted to reuse key: 'square'
However, two enum members are allowed to have the same value. Given two members
A and B with the same value (and A defined first), B is an alias to A. By-value
lookup of the value of A and B will return A. By-name lookup of B will also
return A::
>>> class Shape(Enum):
... square = 2
... diamond = 1
... circle = 3
... alias_for_square = 2
...
>>> Shape.square
<Shape.square: 2>
>>> Shape.alias_for_square
<Shape.square: 2>
>>> Shape(2)
<Shape.square: 2>
Iterating over the members of an enum does not provide the aliases::
>>> list(Shape)
[<Shape.square: 2>, <Shape.diamond: 1>, <Shape.circle: 3>]
The special attribute ``__members__`` is an ordered dictionary mapping names
to members. It includes all names defined in the enumeration, including the
aliases::
>>> for name, member in Shape.__members__.items():
... name, member
...
('square', <Shape.square: 2>)
('diamond', <Shape.diamond: 1>)
('circle', <Shape.circle: 3>)
('alias_for_square', <Shape.square: 2>)
The ``__members__`` attribute can be used for detailed programmatic access to
the enumeration members. For example, finding all the aliases::
>>> [name for name, member in Shape.__members__.items() if member.name != name]
['alias_for_square']
Comparisons
-----------
Enumeration members are compared by identity::
>>> Color.red is Color.red
True
>>> Color.red is Color.blue
False
>>> Color.red is not Color.blue
True
Ordered comparisons between enumeration values are *not* supported. Enum
members are not integers (but see `IntEnum`_ below)::
>>> Color.red < Color.blue
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: unorderable types: Color() < Color()
Equality comparisons are defined though::
>>> Color.blue == Color.red
False
>>> Color.blue != Color.red
True
>>> Color.blue == Color.blue
True
Comparisons against non-enumeration values will always compare not equal
(again, class:`IntEnum` was explicitly designed to behave differently, see
below)::
>>> Color.blue == 2
False
Allowed members and attributes of enumerations
----------------------------------------------
The examples above use integers for enumeration values. Using integers is
short and handy (and provided by default by the `Functional API`_), but not
strictly enforced. In the vast majority of use-cases, one doesn't care what
the actual value of an enumeration is. But if the value *is* important,
enumerations can have arbitrary values.
Enumerations are Python classes, and can have methods and special methods as
usual. If we have this enumeration::
>>> class Mood(Enum):
... funky = 1
... happy = 3
...
... def describe(self):
... # self is the member here
... return self.name, self.value
...
... def __str__(self):
... return 'my custom str! {0}'.format(self.value)
...
... @classmethod
... def favorite_mood(cls):
... # cls here is the enumeration
... return cls.happy
Then::
>>> Mood.favorite_mood()
<Mood.happy: 3>
>>> Mood.happy.describe()
('happy', 3)
>>> str(Mood.funky)
'my custom str! 1'
The rules for what is allowed are as follows: _sunder_ names (starting and
ending with a single underscore) are reserved by enum and cannot be used;
all other attributes defined within an enumeration will become members of this
enumeration, with the exception of *__dunder__* names and descriptors (methods
are also descriptors).
Note: if your enumeration defines :meth:`__new__` and/or :meth:`__init__` then
whatever value(s) were given to the enum member will be passed into those
methods. See `Planet`_ for an example.
Restricted subclassing of enumerations
--------------------------------------
Subclassing an enumeration is allowed only if the enumeration does not define
any members. So this is forbidden::
>>> class MoreColor(Color):
... pink = 17
Traceback (most recent call last):
...
TypeError: Cannot extend enumerations
But this is allowed::
>>> class Foo(Enum):
... def some_behavior(self):
... pass
...
>>> class Bar(Foo):
... happy = 1
... sad = 2
...
Allowing subclassing of enums that define members would lead to a violation of
some important invariants of types and instances. On the other hand, it makes
sense to allow sharing some common behavior between a group of enumerations.
(See `OrderedEnum`_ for an example.)
Pickling
--------
Enumerations can be pickled and unpickled::
>>> from test.test_enum import Fruit
>>> from pickle import dumps, loads
>>> Fruit.tomato is loads(dumps(Fruit.tomato))
True
The usual restrictions for pickling apply: picklable enums must be defined in
the top level of a module, since unpickling requires them to be importable
from that module.
.. warning::
In order to support the singleton nature of enumeration members, pickle
protocol version 2 or higher must be used.
Functional API
--------------
The :class:`Enum` class is callable, providing the following functional API::
>>> Animal = Enum('Animal', 'ant bee cat dog')
>>> Animal
<enum 'Animal'>
>>> Animal.ant
<Animal.ant: 1>
>>> Animal.ant.value
1
>>> list(Animal)
[<Animal.ant: 1>, <Animal.bee: 2>, <Animal.cat: 3>, <Animal.dog: 4>]
The semantics of this API resemble :class:`namedtuple`. The first argument
of the call to :class:`Enum` is the name of the enumeration.
The second argument is the *source* of enumeration member names. It can be a
whitespace-separated string of names, a sequence of names, a sequence of
2-tuples with key/value pairs, or a mapping (e.g. dictionary) of names to
values. The last two options enable assigning arbitrary values to
enumerations; the others auto-assign increasing integers starting with 1. A
new class derived from :class:`Enum` is returned. In other words, the above
assignment to :class:`Animal` is equivalent to::
>>> class Animals(Enum):
... ant = 1
... bee = 2
... cat = 3
... dog = 4
Pickling enums created with the functional API can be tricky as frame stack
implementation details are used to try and figure out which module the
enumeration is being created in (e.g. it will fail if you use a utility
function in separate module, and also may not work on IronPython or Jython).
The solution is to specify the module name explicitly as follows::
>>> Animals = Enum('Animals', 'ant bee cat dog', module=__name__)
Derived Enumerations
====================
IntEnum
-------
A variation of :class:`Enum` is provided which is also a subclass of
:class:`int`. Members of an :class:`IntEnum` can be compared to integers;
by extension, integer enumerations of different types can also be compared
to each other::
>>> from enum import IntEnum
>>> class Shape(IntEnum):
... circle = 1
... square = 2
...
>>> class Request(IntEnum):
... post = 1
... get = 2
...
>>> Shape == 1
False
>>> Shape.circle == 1
True
>>> Shape.circle == Request.post
True
However, they still can't be compared to standard :class:`Enum` enumerations::
>>> class Shape(IntEnum):
... circle = 1
... square = 2
...
>>> class Color(Enum):
... red = 1
... green = 2
...
>>> Shape.circle == Color.red
False
:class:`IntEnum` values behave like integers in other ways you'd expect::
>>> int(Shape.circle)
1
>>> ['a', 'b', 'c'][Shape.circle]
'b'
>>> [i for i in range(Shape.square)]
[0, 1]
For the vast majority of code, :class:`Enum` is strongly recommended,
since :class:`IntEnum` breaks some semantic promises of an enumeration (by
being comparable to integers, and thus by transitivity to other
unrelated enumerations). It should be used only in special cases where
there's no other choice; for example, when integer constants are
replaced with enumerations and backwards compatibility is required with code
that still expects integers.
Others
------
While :class:`IntEnum` is part of the :mod:`enum` module, it would be very
simple to implement independently::
class IntEnum(int, Enum):
pass
This demonstrates how similar derived enumerations can be defined; for example
a :class:`StrEnum` that mixes in :class:`str` 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`
example above.
2. While :class:`Enum` can have members of any type, once you mix in an
additional type, all the members must have values of that type, e.g.
:class:`int` above. This restriction does not apply to mix-ins which only
add methods and don't specify another data type such as :class:`int` or
:class:`str`.
3. When another data type is mixed in, the :attr:`value` attribute is *not the
same* as the enum member itself, although it is equivalant and will compare
equal.
Interesting examples
====================
While :class:`Enum` and :class:`IntEnum` are expected to cover the majority of
use-cases, they cannot cover them all. Here are recipes for some different
types of enumerations that can be used directly, or as examples for creating
one's own.
AutoNumber
----------
Avoids having to specify the value for each enumeration member::
>>> class AutoNumber(Enum):
... def __new__(cls):
... value = len(cls.__members__) + 1
... obj = object.__new__(cls)
... obj._value = value
... return obj
...
>>> class Color(AutoNumber):
... red = ()
... green = ()
... blue = ()
...
>>> Color.green.value == 2
True
UniqueEnum
----------
Raises an error if a duplicate member name is found instead of creating an
alias::
>>> class UniqueEnum(Enum):
... def __init__(self, *args):
... cls = self.__class__
... if any(self.value == e.value for e in cls):
... a = self.name
... e = cls(self.value).name
... raise ValueError(
... "aliases not allowed in UniqueEnum: %r --> %r"
... % (a, e))
...
>>> class Color(UniqueEnum):
... red = 1
... green = 2
... blue = 3
... grene = 2
Traceback (most recent call last):
...
ValueError: aliases not allowed in UniqueEnum: 'grene' --> 'green'
OrderedEnum
-----------
An ordered enumeration that is not based on :class:`IntEnum` and so maintains
the normal :class:`Enum` invariants (such as not being comparable to other
enumerations)::
>>> class OrderedEnum(Enum):
... def __ge__(self, other):
... if self.__class__ is other.__class__:
... return self._value >= other._value
... return NotImplemented
... def __gt__(self, other):
... if self.__class__ is other.__class__:
... return self._value > other._value
... return NotImplemented
... def __le__(self, other):
... if self.__class__ is other.__class__:
... return self._value <= other._value
... return NotImplemented
... def __lt__(self, other):
... if self.__class__ is other.__class__:
... return self._value < other._value
... return NotImplemented
...
>>> class Grade(OrderedEnum):
... A = 5
... B = 4
... C = 3
... D = 2
... F = 1
...
>>> Grade.C < Grade.A
True
Planet
------
If :meth:`__new__` or :meth:`__init__` is defined the value of the enum member
will be passed to those methods::
>>> class Planet(Enum):
... MERCURY = (3.303e+23, 2.4397e6)
... VENUS = (4.869e+24, 6.0518e6)
... EARTH = (5.976e+24, 6.37814e6)
... MARS = (6.421e+23, 3.3972e6)
... JUPITER = (1.9e+27, 7.1492e7)
... SATURN = (5.688e+26, 6.0268e7)
... URANUS = (8.686e+25, 2.5559e7)
... NEPTUNE = (1.024e+26, 2.4746e7)
... def __init__(self, mass, radius):
... self.mass = mass # in kilograms
... self.radius = radius # in meters
... @property
... def surface_gravity(self):
... # universal gravitational constant (m3 kg-1 s-2)
... G = 6.67300E-11
... return G * self.mass / (self.radius * self.radius)
...
>>> Planet.EARTH.value
(5.976e+24, 6378140.0)
>>> Planet.EARTH.surface_gravity
9.802652743337129

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"""Python Enumerations"""
import sys
from collections import OrderedDict
from types import MappingProxyType
__all__ = ['Enum', 'IntEnum']
class _RouteClassAttributeToGetattr:
"""Route attribute access on a class to __getattr__.
This is a descriptor, used to define attributes that act differently when
accessed through an instance and through a class. Instance access remains
normal, but access to an attribute through a class will be routed to the
class's __getattr__ method; this is done by raising AttributeError.
"""
def __init__(self, fget=None):
self.fget = fget
def __get__(self, instance, ownerclass=None):
if instance is None:
raise AttributeError()
return self.fget(instance)
def __set__(self, instance, value):
raise AttributeError("can't set attribute")
def __delete__(self, instance):
raise AttributeError("can't delete attribute")
def _is_dunder(name):
"""Returns True if a __dunder__ name, False otherwise."""
return (name[:2] == name[-2:] == '__' and
name[2:3] != '_' and
name[-3:-2] != '_')
def _is_sunder(name):
"""Returns True if a _sunder_ name, False otherwise."""
return (name[0] == name[-1] == '_' and
name[1:2] != '_' and
name[-2:-1] != '_')
def _make_class_unpicklable(cls):
"""Make the given class un-picklable."""
def _break_on_call_reduce(self):
raise TypeError('%r cannot be pickled' % self)
cls.__reduce__ = _break_on_call_reduce
cls.__module__ = '<unknown>'
class _EnumDict(dict):
"""Keeps track of definition order of the enum items.
EnumMeta will use the names found in self._member_names as the
enumeration member names.
"""
def __init__(self):
super().__init__()
self._member_names = []
def __setitem__(self, key, value):
"""Changes anything not dundered or that doesn't have __get__.
If a descriptor is added with the same name as an enum member, the name
is removed from _member_names (this may leave a hole in the numerical
sequence of values).
If an enum member name is used twice, an error is raised; duplicate
values are not checked for.
Single underscore (sunder) names are reserved.
"""
if _is_sunder(key):
raise ValueError('_names_ are reserved for future Enum use')
elif _is_dunder(key) or hasattr(value, '__get__'):
if key in self._member_names:
# overwriting an enum with a method? then remove the name from
# _member_names or it will become an enum anyway when the class
# is created
self._member_names.remove(key)
else:
if key in self._member_names:
raise TypeError('Attempted to reuse key: %r' % key)
self._member_names.append(key)
super().__setitem__(key, value)
# Dummy value for Enum as EnumMeta explicity checks for it, but of course until
# EnumMeta finishes running the first time the Enum class doesn't exist. This
# is also why there are checks in EnumMeta like `if Enum is not None`
Enum = None
class EnumMeta(type):
"""Metaclass for Enum"""
@classmethod
def __prepare__(metacls, cls, bases):
return _EnumDict()
def __new__(metacls, cls, bases, classdict):
# an Enum class is final once enumeration items have been defined; it
# cannot be mixed with other types (int, float, etc.) if it has an
# inherited __new__ unless a new __new__ is defined (or the resulting
# class will fail).
member_type, first_enum = metacls._get_mixins_(bases)
__new__, save_new, use_args = metacls._find_new_(classdict, member_type,
first_enum)
# save enum items into separate mapping so they don't get baked into
# the new class
members = {k: classdict[k] for k in classdict._member_names}
for name in classdict._member_names:
del classdict[name]
# check for illegal enum names (any others?)
invalid_names = set(members) & {'mro', }
if invalid_names:
raise ValueError('Invalid enum member name: {0}'.format(
','.join(invalid_names)))
# create our new Enum type
enum_class = super().__new__(metacls, cls, bases, classdict)
enum_class._member_names = [] # names in definition order
enum_class._member_map = OrderedDict() # name->value map
# Reverse value->name map for hashable values.
enum_class._value2member_map = {}
# check for a __getnewargs__, and if not present sabotage
# pickling, since it won't work anyway
if (member_type is not object and
member_type.__dict__.get('__getnewargs__') is None
):
_make_class_unpicklable(enum_class)
# instantiate them, checking for duplicates as we go
# we instantiate first instead of checking for duplicates first in case
# a custom __new__ is doing something funky with the values -- such as
# auto-numbering ;)
for member_name in classdict._member_names:
value = members[member_name]
if not isinstance(value, tuple):
args = (value, )
else:
args = value
if member_type is tuple: # special case for tuple enums
args = (args, ) # wrap it one more time
if not use_args:
enum_member = __new__(enum_class)
enum_member._value = value
else:
enum_member = __new__(enum_class, *args)
if not hasattr(enum_member, '_value'):
enum_member._value = member_type(*args)
enum_member._member_type = member_type
enum_member._name = member_name
enum_member.__init__(*args)
# If another member with the same value was already defined, the
# new member becomes an alias to the existing one.
for name, canonical_member in enum_class._member_map.items():
if canonical_member.value == enum_member._value:
enum_member = canonical_member
break
else:
# Aliases don't appear in member names (only in __members__).
enum_class._member_names.append(member_name)
enum_class._member_map[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
# linear.
enum_class._value2member_map[value] = enum_member
except TypeError:
pass
# double check that repr and friends are not the mixin's or various
# things break (such as pickle)
for name in ('__repr__', '__str__', '__getnewargs__'):
class_method = getattr(enum_class, name)
obj_method = getattr(member_type, name, None)
enum_method = getattr(first_enum, name, None)
if obj_method is not None and obj_method is class_method:
setattr(enum_class, name, enum_method)
# replace any other __new__ with our own (as long as Enum is not None,
# anyway) -- again, this is to support pickle
if Enum is not None:
# if the user defined their own __new__, save it before it gets
# clobbered in case they subclass later
if save_new:
enum_class.__new_member__ = __new__
enum_class.__new__ = Enum.__new__
return enum_class
def __call__(cls, value, names=None, *, module=None, type=None):
"""Either returns an existing member, or creates a new enum class.
This method is used both when an enum class is given a value to match
to an enumeration member (i.e. Color(3)) and for the functional API
(i.e. Color = Enum('Color', names='red green blue')).
When used for the functional API: `module`, if set, will be stored in
the new class' __module__ attribute; `type`, if set, will be mixed in
as the first base class.
Note: if `module` is not set this routine will attempt to discover the
calling module by walking the frame stack; if this is unsuccessful
the resulting class will not be pickleable.
"""
if names is None: # simple value lookup
return cls.__new__(cls, value)
# otherwise, functional API: we're creating a new Enum type
return cls._create_(value, names, module=module, type=type)
def __contains__(cls, member):
return isinstance(member, cls) and member.name in cls._member_map
def __dir__(self):
return ['__class__', '__doc__', '__members__'] + self._member_names
@property
def __members__(cls):
"""Returns a mapping of member name->value.
This mapping lists all enum members, including aliases. Note that this
is a read-only view of the internal mapping.
"""
return MappingProxyType(cls._member_map)
def __getattr__(cls, name):
"""Return the enum member matching `name`
We use __getattr__ instead of descriptors or inserting into the enum
class' __dict__ in order to support `name` and `value` being both
properties for enum members (which live in the class' __dict__) and
enum members themselves.
"""
if _is_dunder(name):
raise AttributeError(name)
try:
return cls._member_map[name]
except KeyError:
raise AttributeError(name) from None
def __getitem__(cls, name):
return cls._member_map[name]
def __iter__(cls):
return (cls._member_map[name] for name in cls._member_names)
def __len__(cls):
return len(cls._member_names)
def __repr__(cls):
return "<enum %r>" % cls.__name__
def _create_(cls, class_name, names=None, *, module=None, type=None):
"""Convenience method to create a new Enum class.
`names` can be:
* A string containing member names, separated either with spaces or
commas. Values are auto-numbered from 1.
* An iterable of member names. Values are auto-numbered from 1.
* An iterable of (member name, value) pairs.
* A mapping of member name -> value.
"""
metacls = cls.__class__
bases = (cls, ) if type is None else (type, cls)
classdict = metacls.__prepare__(class_name, bases)
# special processing needed for names?
if isinstance(names, str):
names = names.replace(',', ' ').split()
if isinstance(names, (tuple, list)) and isinstance(names[0], str):
names = [(e, i) for (i, e) in enumerate(names, 1)]
# Here, names is either an iterable of (name, value) or a mapping.
for item in names:
if isinstance(item, str):
member_name, member_value = item, names[item]
else:
member_name, member_value = item
classdict[member_name] = member_value
enum_class = metacls.__new__(metacls, class_name, bases, classdict)
# TODO: replace the frame hack if a blessed way to know the calling
# module is ever developed
if module is None:
try:
module = sys._getframe(2).f_globals['__name__']
except (AttributeError, ValueError) as exc:
pass
if module is None:
_make_class_unpicklable(enum_class)
else:
enum_class.__module__ = module
return enum_class
@staticmethod
def _get_mixins_(bases):
"""Returns the type for creating enum members, and the first inherited
enum class.
bases: the tuple of bases that was given to __new__
"""
if not bases:
return object, Enum
# double check that we are not subclassing a class with existing
# enumeration members; while we're at it, see if any other data
# type has been mixed in so we can use the correct __new__
member_type = first_enum = None
for base in bases:
if (base is not Enum and
issubclass(base, Enum) and
base._member_names):
raise TypeError("Cannot extend enumerations")
# base is now the last base in bases
if not issubclass(base, Enum):
raise TypeError("new enumerations must be created as "
"`ClassName([mixin_type,] enum_type)`")
# get correct mix-in type (either mix-in type of Enum subclass, or
# first base if last base is Enum)
if not issubclass(bases[0], Enum):
member_type = bases[0] # first data type
first_enum = bases[-1] # enum type
else:
for base in bases[0].__mro__:
# most common: (IntEnum, int, Enum, object)
# possible: (<Enum 'AutoIntEnum'>, <Enum 'IntEnum'>,
# <class 'int'>, <Enum 'Enum'>,
# <class 'object'>)
if issubclass(base, Enum):
if first_enum is None:
first_enum = base
else:
if member_type is None:
member_type = base
return member_type, first_enum
@staticmethod
def _find_new_(classdict, member_type, first_enum):
"""Returns the __new__ to be used for creating the enum members.
classdict: the class dictionary given to __new__
member_type: the data type whose __new__ will be used by default
first_enum: enumeration to check for an overriding __new__
"""
# now find the correct __new__, checking to see of one was defined
# by the user; also check earlier enum classes in case a __new__ was
# saved as __new_member__
__new__ = classdict.get('__new__', None)
# should __new__ be saved as __new_member__ later?
save_new = __new__ is not None
if __new__ is None:
# check all possibles for __new_member__ before falling back to
# __new__
for method in ('__new_member__', '__new__'):
for possible in (member_type, first_enum):
target = getattr(possible, method, None)
if target not in {
None,
None.__new__,
object.__new__,
Enum.__new__,
}:
__new__ = target
break
if __new__ is not None:
break
else:
__new__ = object.__new__
# if a non-object.__new__ is used then whatever value/tuple was
# assigned to the enum member name will be passed to __new__ and to the
# new enum member's __init__
if __new__ is object.__new__:
use_args = False
else:
use_args = True
return __new__, save_new, use_args
class Enum(metaclass=EnumMeta):
"""Generic enumeration.
Derive from this class to define new enumerations.
"""
def __new__(cls, value):
# all enum instances are actually created during class construction
# without calling this method; this method is called by the metaclass'
# __call__ (i.e. Color(3) ), and by pickle
if type(value) is cls:
# For lookups like Color(Color.red)
return value
# by-value search for a matching enum member
# see if it's in the reverse mapping (for hashable values)
if value in cls._value2member_map:
return cls._value2member_map[value]
# not there, now do long search -- O(n) behavior
for member in cls._member_map.values():
if member.value == value:
return member
raise ValueError("%s is not a valid %s" % (value, cls.__name__))
def __repr__(self):
return "<%s.%s: %r>" % (
self.__class__.__name__, self._name, self._value)
def __str__(self):
return "%s.%s" % (self.__class__.__name__, self._name)
def __dir__(self):
return (['__class__', '__doc__', 'name', 'value'])
def __eq__(self, other):
if type(other) is self.__class__:
return self is other
return NotImplemented
def __getnewargs__(self):
return (self._value, )
def __hash__(self):
return hash(self._name)
# _RouteClassAttributeToGetattr is used to provide access to the `name`
# and `value` properties of enum members while keeping some measure of
# protection from modification, while still allowing for an enumeration
# to have members named `name` and `value`. This works because enumeration
# members are not set directly on the enum class -- __getattr__ is
# used to look them up.
@_RouteClassAttributeToGetattr
def name(self):
return self._name
@_RouteClassAttributeToGetattr
def value(self):
return self._value
class IntEnum(int, Enum):
"""Enum where members are also (and must be) ints"""

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import enum
import unittest
from collections import OrderedDict
from pickle import dumps, loads, PicklingError
from enum import Enum, IntEnum
# for pickle tests
try:
class Stooges(Enum):
LARRY = 1
CURLY = 2
MOE = 3
except Exception as exc:
Stooges = exc
try:
class IntStooges(int, Enum):
LARRY = 1
CURLY = 2
MOE = 3
except Exception as exc:
IntStooges = exc
try:
class FloatStooges(float, Enum):
LARRY = 1.39
CURLY = 2.72
MOE = 3.142596
except Exception as exc:
FloatStooges = exc
# for pickle test and subclass tests
try:
class StrEnum(str, Enum):
'accepts only string values'
class Name(StrEnum):
BDFL = 'Guido van Rossum'
FLUFL = 'Barry Warsaw'
except Exception as exc:
Name = exc
try:
Question = Enum('Question', 'who what when where why', module=__name__)
except Exception as exc:
Question = exc
try:
Answer = Enum('Answer', 'him this then there because')
except Exception as exc:
Answer = exc
# for doctests
try:
class Fruit(Enum):
tomato = 1
banana = 2
cherry = 3
except Exception:
pass
class TestEnum(unittest.TestCase):
def setUp(self):
class Season(Enum):
SPRING = 1
SUMMER = 2
AUTUMN = 3
WINTER = 4
self.Season = Season
def test_enum_in_enum_out(self):
Season = self.Season
self.assertIs(Season(Season.WINTER), Season.WINTER)
def test_enum_value(self):
Season = self.Season
self.assertEqual(Season.SPRING.value, 1)
def test_intenum_value(self):
self.assertEqual(IntStooges.CURLY.value, 2)
def test_dir_on_class(self):
Season = self.Season
self.assertEqual(
set(dir(Season)),
set(['__class__', '__doc__', '__members__',
'SPRING', 'SUMMER', 'AUTUMN', 'WINTER']),
)
def test_dir_on_item(self):
Season = self.Season
self.assertEqual(
set(dir(Season.WINTER)),
set(['__class__', '__doc__', 'name', 'value']),
)
def test_enum(self):
Season = self.Season
lst = list(Season)
self.assertEqual(len(lst), len(Season))
self.assertEqual(len(Season), 4, Season)
self.assertEqual(
[Season.SPRING, Season.SUMMER, Season.AUTUMN, Season.WINTER], lst)
for i, season in enumerate('SPRING SUMMER AUTUMN WINTER'.split(), 1):
e = Season(i)
self.assertEqual(e, getattr(Season, season))
self.assertEqual(e.value, i)
self.assertNotEqual(e, i)
self.assertEqual(e.name, season)
self.assertIn(e, Season)
self.assertIs(type(e), Season)
self.assertIsInstance(e, Season)
self.assertEqual(str(e), 'Season.' + season)
self.assertEqual(
repr(e),
'<Season.{0}: {1}>'.format(season, i),
)
def test_value_name(self):
Season = self.Season
self.assertEqual(Season.SPRING.name, 'SPRING')
self.assertEqual(Season.SPRING.value, 1)
with self.assertRaises(AttributeError):
Season.SPRING.name = 'invierno'
with self.assertRaises(AttributeError):
Season.SPRING.value = 2
def test_invalid_names(self):
with self.assertRaises(ValueError):
class Wrong(Enum):
mro = 9
with self.assertRaises(ValueError):
class Wrong(Enum):
_create_= 11
with self.assertRaises(ValueError):
class Wrong(Enum):
_get_mixins_ = 9
with self.assertRaises(ValueError):
class Wrong(Enum):
_find_new_ = 1
with self.assertRaises(ValueError):
class Wrong(Enum):
_any_name_ = 9
def test_contains(self):
Season = self.Season
self.assertIn(Season.AUTUMN, Season)
self.assertNotIn(3, Season)
val = Season(3)
self.assertIn(val, Season)
class OtherEnum(Enum):
one = 1; two = 2
self.assertNotIn(OtherEnum.two, Season)
def test_comparisons(self):
Season = self.Season
with self.assertRaises(TypeError):
Season.SPRING < Season.WINTER
with self.assertRaises(TypeError):
Season.SPRING > 4
self.assertNotEqual(Season.SPRING, 1)
class Part(Enum):
SPRING = 1
CLIP = 2
BARREL = 3
self.assertNotEqual(Season.SPRING, Part.SPRING)
with self.assertRaises(TypeError):
Season.SPRING < Part.CLIP
def test_enum_duplicates(self):
class Season(Enum):
SPRING = 1
SUMMER = 2
AUTUMN = FALL = 3
WINTER = 4
ANOTHER_SPRING = 1
lst = list(Season)
self.assertEqual(
lst,
[Season.SPRING, Season.SUMMER,
Season.AUTUMN, Season.WINTER,
])
self.assertIs(Season.FALL, Season.AUTUMN)
self.assertEqual(Season.FALL.value, 3)
self.assertEqual(Season.AUTUMN.value, 3)
self.assertIs(Season(3), Season.AUTUMN)
self.assertIs(Season(1), Season.SPRING)
self.assertEqual(Season.FALL.name, 'AUTUMN')
self.assertEqual(
[k for k,v in Season.__members__.items() if v.name != k],
['FALL', 'ANOTHER_SPRING'],
)
def test_enum_with_value_name(self):
class Huh(Enum):
name = 1
value = 2
self.assertEqual(
list(Huh),
[Huh.name, Huh.value],
)
self.assertIs(type(Huh.name), Huh)
self.assertEqual(Huh.name.name, 'name')
self.assertEqual(Huh.name.value, 1)
def test_hash(self):
Season = self.Season
dates = {}
dates[Season.WINTER] = '1225'
dates[Season.SPRING] = '0315'
dates[Season.SUMMER] = '0704'
dates[Season.AUTUMN] = '1031'
self.assertEqual(dates[Season.AUTUMN], '1031')
def test_intenum_from_scratch(self):
class phy(int, Enum):
pi = 3
tau = 2 * pi
self.assertTrue(phy.pi < phy.tau)
def test_intenum_inherited(self):
class IntEnum(int, Enum):
pass
class phy(IntEnum):
pi = 3
tau = 2 * pi
self.assertTrue(phy.pi < phy.tau)
def test_floatenum_from_scratch(self):
class phy(float, Enum):
pi = 3.141596
tau = 2 * pi
self.assertTrue(phy.pi < phy.tau)
def test_floatenum_inherited(self):
class FloatEnum(float, Enum):
pass
class phy(FloatEnum):
pi = 3.141596
tau = 2 * pi
self.assertTrue(phy.pi < phy.tau)
def test_strenum_from_scratch(self):
class phy(str, Enum):
pi = 'Pi'
tau = 'Tau'
self.assertTrue(phy.pi < phy.tau)
def test_strenum_inherited(self):
class StrEnum(str, Enum):
pass
class phy(StrEnum):
pi = 'Pi'
tau = 'Tau'
self.assertTrue(phy.pi < phy.tau)
def test_intenum(self):
class WeekDay(IntEnum):
SUNDAY = 1
MONDAY = 2
TUESDAY = 3
WEDNESDAY = 4
THURSDAY = 5
FRIDAY = 6
SATURDAY = 7
self.assertEqual(['a', 'b', 'c'][WeekDay.MONDAY], 'c')
self.assertEqual([i for i in range(WeekDay.TUESDAY)], [0, 1, 2])
lst = list(WeekDay)
self.assertEqual(len(lst), len(WeekDay))
self.assertEqual(len(WeekDay), 7)
target = 'SUNDAY MONDAY TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY'
target = target.split()
for i, weekday in enumerate(target, 1):
e = WeekDay(i)
self.assertEqual(e, i)
self.assertEqual(int(e), i)
self.assertEqual(e.name, weekday)
self.assertIn(e, WeekDay)
self.assertEqual(lst.index(e)+1, i)
self.assertTrue(0 < e < 8)
self.assertIs(type(e), WeekDay)
self.assertIsInstance(e, int)
self.assertIsInstance(e, Enum)
def test_intenum_duplicates(self):
class WeekDay(IntEnum):
SUNDAY = 1
MONDAY = 2
TUESDAY = TEUSDAY = 3
WEDNESDAY = 4
THURSDAY = 5
FRIDAY = 6
SATURDAY = 7
self.assertIs(WeekDay.TEUSDAY, WeekDay.TUESDAY)
self.assertEqual(WeekDay(3).name, 'TUESDAY')
self.assertEqual([k for k,v in WeekDay.__members__.items()
if v.name != k], ['TEUSDAY', ])
def test_pickle_enum(self):
if isinstance(Stooges, Exception):
raise Stooges
self.assertIs(Stooges.CURLY, loads(dumps(Stooges.CURLY)))
self.assertIs(Stooges, loads(dumps(Stooges)))
def test_pickle_int(self):
if isinstance(IntStooges, Exception):
raise IntStooges
self.assertIs(IntStooges.CURLY, loads(dumps(IntStooges.CURLY)))
self.assertIs(IntStooges, loads(dumps(IntStooges)))
def test_pickle_float(self):
if isinstance(FloatStooges, Exception):
raise FloatStooges
self.assertIs(FloatStooges.CURLY, loads(dumps(FloatStooges.CURLY)))
self.assertIs(FloatStooges, loads(dumps(FloatStooges)))
def test_pickle_enum_function(self):
if isinstance(Answer, Exception):
raise Answer
self.assertIs(Answer.him, loads(dumps(Answer.him)))
self.assertIs(Answer, loads(dumps(Answer)))
def test_pickle_enum_function_with_module(self):
if isinstance(Question, Exception):
raise Question
self.assertIs(Question.who, loads(dumps(Question.who)))
self.assertIs(Question, loads(dumps(Question)))
def test_exploding_pickle(self):
BadPickle = Enum('BadPickle', 'dill sweet bread-n-butter')
enum._make_class_unpicklable(BadPickle)
globals()['BadPickle'] = BadPickle
with self.assertRaises(TypeError):
dumps(BadPickle.dill)
with self.assertRaises(PicklingError):
dumps(BadPickle)
def test_string_enum(self):
class SkillLevel(str, Enum):
master = 'what is the sound of one hand clapping?'
journeyman = 'why did the chicken cross the road?'
apprentice = 'knock, knock!'
self.assertEqual(SkillLevel.apprentice, 'knock, knock!')
def test_getattr_getitem(self):
class Period(Enum):
morning = 1
noon = 2
evening = 3
night = 4
self.assertIs(Period(2), Period.noon)
self.assertIs(getattr(Period, 'night'), Period.night)
self.assertIs(Period['morning'], Period.morning)
def test_getattr_dunder(self):
Season = self.Season
self.assertTrue(getattr(Season, '__eq__'))
def test_iteration_order(self):
class Season(Enum):
SUMMER = 2
WINTER = 4
AUTUMN = 3
SPRING = 1
self.assertEqual(
list(Season),
[Season.SUMMER, Season.WINTER, Season.AUTUMN, Season.SPRING],
)
def test_programatic_function_string(self):
SummerMonth = Enum('SummerMonth', 'june july august')
lst = list(SummerMonth)
self.assertEqual(len(lst), len(SummerMonth))
self.assertEqual(len(SummerMonth), 3, SummerMonth)
self.assertEqual(
[SummerMonth.june, SummerMonth.july, SummerMonth.august],
lst,
)
for i, month in enumerate('june july august'.split(), 1):
e = SummerMonth(i)
self.assertEqual(int(e.value), i)
self.assertNotEqual(e, i)
self.assertEqual(e.name, month)
self.assertIn(e, SummerMonth)
self.assertIs(type(e), SummerMonth)
def test_programatic_function_string_list(self):
SummerMonth = Enum('SummerMonth', ['june', 'july', 'august'])
lst = list(SummerMonth)
self.assertEqual(len(lst), len(SummerMonth))
self.assertEqual(len(SummerMonth), 3, SummerMonth)
self.assertEqual(
[SummerMonth.june, SummerMonth.july, SummerMonth.august],
lst,
)
for i, month in enumerate('june july august'.split(), 1):
e = SummerMonth(i)
self.assertEqual(int(e.value), i)
self.assertNotEqual(e, i)
self.assertEqual(e.name, month)
self.assertIn(e, SummerMonth)
self.assertIs(type(e), SummerMonth)
def test_programatic_function_iterable(self):
SummerMonth = Enum(
'SummerMonth',
(('june', 1), ('july', 2), ('august', 3))
)
lst = list(SummerMonth)
self.assertEqual(len(lst), len(SummerMonth))
self.assertEqual(len(SummerMonth), 3, SummerMonth)
self.assertEqual(
[SummerMonth.june, SummerMonth.july, SummerMonth.august],
lst,
)
for i, month in enumerate('june july august'.split(), 1):
e = SummerMonth(i)
self.assertEqual(int(e.value), i)
self.assertNotEqual(e, i)
self.assertEqual(e.name, month)
self.assertIn(e, SummerMonth)
self.assertIs(type(e), SummerMonth)
def test_programatic_function_from_dict(self):
SummerMonth = Enum(
'SummerMonth',
OrderedDict((('june', 1), ('july', 2), ('august', 3)))
)
lst = list(SummerMonth)
self.assertEqual(len(lst), len(SummerMonth))
self.assertEqual(len(SummerMonth), 3, SummerMonth)
self.assertEqual(
[SummerMonth.june, SummerMonth.july, SummerMonth.august],
lst,
)
for i, month in enumerate('june july august'.split(), 1):
e = SummerMonth(i)
self.assertEqual(int(e.value), i)
self.assertNotEqual(e, i)
self.assertEqual(e.name, month)
self.assertIn(e, SummerMonth)
self.assertIs(type(e), SummerMonth)
def test_programatic_function_type(self):
SummerMonth = Enum('SummerMonth', 'june july august', type=int)
lst = list(SummerMonth)
self.assertEqual(len(lst), len(SummerMonth))
self.assertEqual(len(SummerMonth), 3, SummerMonth)
self.assertEqual(
[SummerMonth.june, SummerMonth.july, SummerMonth.august],
lst,
)
for i, month in enumerate('june july august'.split(), 1):
e = SummerMonth(i)
self.assertEqual(e, i)
self.assertEqual(e.name, month)
self.assertIn(e, SummerMonth)
self.assertIs(type(e), SummerMonth)
def test_programatic_function_type_from_subclass(self):
SummerMonth = IntEnum('SummerMonth', 'june july august')
lst = list(SummerMonth)
self.assertEqual(len(lst), len(SummerMonth))
self.assertEqual(len(SummerMonth), 3, SummerMonth)
self.assertEqual(
[SummerMonth.june, SummerMonth.july, SummerMonth.august],
lst,
)
for i, month in enumerate('june july august'.split(), 1):
e = SummerMonth(i)
self.assertEqual(e, i)
self.assertEqual(e.name, month)
self.assertIn(e, SummerMonth)
self.assertIs(type(e), SummerMonth)
def test_subclassing(self):
if isinstance(Name, Exception):
raise Name
self.assertEqual(Name.BDFL, 'Guido van Rossum')
self.assertTrue(Name.BDFL, Name('Guido van Rossum'))
self.assertIs(Name.BDFL, getattr(Name, 'BDFL'))
self.assertIs(Name.BDFL, loads(dumps(Name.BDFL)))
def test_extending(self):
class Color(Enum):
red = 1
green = 2
blue = 3
with self.assertRaises(TypeError):
class MoreColor(Color):
cyan = 4
magenta = 5
yellow = 6
def test_exclude_methods(self):
class whatever(Enum):
this = 'that'
these = 'those'
def really(self):
return 'no, not %s' % self.value
self.assertIsNot(type(whatever.really), whatever)
self.assertEqual(whatever.this.really(), 'no, not that')
def test_overwrite_enums(self):
class Why(Enum):
question = 1
answer = 2
propisition = 3
def question(self):
print(42)
self.assertIsNot(type(Why.question), Why)
self.assertNotIn(Why.question, Why._member_names)
self.assertNotIn(Why.question, Why)
def test_wrong_inheritance_order(self):
with self.assertRaises(TypeError):
class Wrong(Enum, str):
NotHere = 'error before this point'
def test_intenum_transitivity(self):
class number(IntEnum):
one = 1
two = 2
three = 3
class numero(IntEnum):
uno = 1
dos = 2
tres = 3
self.assertEqual(number.one, numero.uno)
self.assertEqual(number.two, numero.dos)
self.assertEqual(number.three, numero.tres)
def test_wrong_enum_in_call(self):
class Monochrome(Enum):
black = 0
white = 1
class Gender(Enum):
male = 0
female = 1
self.assertRaises(ValueError, Monochrome, Gender.male)
def test_wrong_enum_in_mixed_call(self):
class Monochrome(IntEnum):
black = 0
white = 1
class Gender(Enum):
male = 0
female = 1
self.assertRaises(ValueError, Monochrome, Gender.male)
def test_mixed_enum_in_call_1(self):
class Monochrome(IntEnum):
black = 0
white = 1
class Gender(IntEnum):
male = 0
female = 1
self.assertIs(Monochrome(Gender.female), Monochrome.white)
def test_mixed_enum_in_call_2(self):
class Monochrome(Enum):
black = 0
white = 1
class Gender(IntEnum):
male = 0
female = 1
self.assertIs(Monochrome(Gender.male), Monochrome.black)
def test_flufl_enum(self):
class Fluflnum(Enum):
def __int__(self):
return int(self.value)
class MailManOptions(Fluflnum):
option1 = 1
option2 = 2
option3 = 3
self.assertEqual(int(MailManOptions.option1), 1)
def test_no_such_enum_member(self):
class Color(Enum):
red = 1
green = 2
blue = 3
with self.assertRaises(ValueError):
Color(4)
with self.assertRaises(KeyError):
Color['chartreuse']
def test_new_repr(self):
class Color(Enum):
red = 1
green = 2
blue = 3
def __repr__(self):
return "don't you just love shades of %s?" % self.name
self.assertEqual(
repr(Color.blue),
"don't you just love shades of blue?",
)
def test_inherited_repr(self):
class MyEnum(Enum):
def __repr__(self):
return "My name is %s." % self.name
class MyIntEnum(int, MyEnum):
this = 1
that = 2
theother = 3
self.assertEqual(repr(MyIntEnum.that), "My name is that.")
def test_multiple_mixin_mro(self):
class auto_enum(type(Enum)):
def __new__(metacls, cls, bases, classdict):
temp = type(classdict)()
names = set(classdict._member_names)
i = 0
for k in classdict._member_names:
v = classdict[k]
if v is Ellipsis:
v = i
else:
i = v
i += 1
temp[k] = v
for k, v in classdict.items():
if k not in names:
temp[k] = v
return super(auto_enum, metacls).__new__(
metacls, cls, bases, temp)
class AutoNumberedEnum(Enum, metaclass=auto_enum):
pass
class AutoIntEnum(IntEnum, metaclass=auto_enum):
pass
class TestAutoNumber(AutoNumberedEnum):
a = ...
b = 3
c = ...
class TestAutoInt(AutoIntEnum):
a = ...
b = 3
c = ...
def test_subclasses_with_getnewargs(self):
class NamedInt(int):
def __new__(cls, *args):
_args = args
name, *args = args
if len(args) == 0:
raise TypeError("name and value must be specified")
self = int.__new__(cls, *args)
self._intname = name
self._args = _args
return self
def __getnewargs__(self):
return self._args
@property
def __name__(self):
return self._intname
def __repr__(self):
# repr() is updated to include the name and type info
return "{}({!r}, {})".format(type(self).__name__,
self.__name__,
int.__repr__(self))
def __str__(self):
# str() is unchanged, even if it relies on the repr() fallback
base = int
base_str = base.__str__
if base_str.__objclass__ is object:
return base.__repr__(self)
return base_str(self)
# for simplicity, we only define one operator that
# propagates expressions
def __add__(self, other):
temp = int(self) + int( other)
if isinstance(self, NamedInt) and isinstance(other, NamedInt):
return NamedInt(
'({0} + {1})'.format(self.__name__, other.__name__),
temp )
else:
return temp
class NEI(NamedInt, Enum):
x = ('the-x', 1)
y = ('the-y', 2)
self.assertIs(NEI.__new__, Enum.__new__)
self.assertEqual(repr(NEI.x + NEI.y), "NamedInt('(the-x + the-y)', 3)")
globals()['NamedInt'] = NamedInt
globals()['NEI'] = NEI
NI5 = NamedInt('test', 5)
self.assertEqual(NI5, 5)
self.assertEqual(loads(dumps(NI5)), 5)
self.assertEqual(NEI.y.value, 2)
self.assertIs(loads(dumps(NEI.y)), NEI.y)
def test_subclasses_without_getnewargs(self):
class NamedInt(int):
def __new__(cls, *args):
_args = args
name, *args = args
if len(args) == 0:
raise TypeError("name and value must be specified")
self = int.__new__(cls, *args)
self._intname = name
self._args = _args
return self
@property
def __name__(self):
return self._intname
def __repr__(self):
# repr() is updated to include the name and type info
return "{}({!r}, {})".format(type(self).__name__,
self.__name__,
int.__repr__(self))
def __str__(self):
# str() is unchanged, even if it relies on the repr() fallback
base = int
base_str = base.__str__
if base_str.__objclass__ is object:
return base.__repr__(self)
return base_str(self)
# for simplicity, we only define one operator that
# propagates expressions
def __add__(self, other):
temp = int(self) + int( other)
if isinstance(self, NamedInt) and isinstance(other, NamedInt):
return NamedInt(
'({0} + {1})'.format(self.__name__, other.__name__),
temp )
else:
return temp
class NEI(NamedInt, Enum):
x = ('the-x', 1)
y = ('the-y', 2)
self.assertIs(NEI.__new__, Enum.__new__)
self.assertEqual(repr(NEI.x + NEI.y), "NamedInt('(the-x + the-y)', 3)")
globals()['NamedInt'] = NamedInt
globals()['NEI'] = NEI
NI5 = NamedInt('test', 5)
self.assertEqual(NI5, 5)
self.assertEqual(NEI.y.value, 2)
with self.assertRaises(TypeError):
dumps(NEI.x)
with self.assertRaises(PicklingError):
dumps(NEI)
def test_tuple_subclass(self):
class SomeTuple(tuple, Enum):
first = (1, 'for the money')
second = (2, 'for the show')
third = (3, 'for the music')
self.assertIs(type(SomeTuple.first), SomeTuple)
self.assertIsInstance(SomeTuple.second, tuple)
self.assertEqual(SomeTuple.third, (3, 'for the music'))
globals()['SomeTuple'] = SomeTuple
self.assertIs(loads(dumps(SomeTuple.first)), SomeTuple.first)
def test_duplicate_values_give_unique_enum_items(self):
class AutoNumber(Enum):
first = ()
second = ()
third = ()
def __new__(cls):
value = len(cls.__members__) + 1
obj = object.__new__(cls)
obj._value = value
return obj
def __int__(self):
return int(self._value)
self.assertEqual(
list(AutoNumber),
[AutoNumber.first, AutoNumber.second, AutoNumber.third],
)
self.assertEqual(int(AutoNumber.second), 2)
self.assertIs(AutoNumber(1), AutoNumber.first)
def test_inherited_new_from_enhanced_enum(self):
class AutoNumber(Enum):
def __new__(cls):
value = len(cls.__members__) + 1
obj = object.__new__(cls)
obj._value = value
return obj
def __int__(self):
return int(self._value)
class Color(AutoNumber):
red = ()
green = ()
blue = ()
self.assertEqual(list(Color), [Color.red, Color.green, Color.blue])
self.assertEqual(list(map(int, Color)), [1, 2, 3])
def test_inherited_new_from_mixed_enum(self):
class AutoNumber(IntEnum):
def __new__(cls):
value = len(cls.__members__) + 1
obj = int.__new__(cls, value)
obj._value = value
return obj
class Color(AutoNumber):
red = ()
green = ()
blue = ()
self.assertEqual(list(Color), [Color.red, Color.green, Color.blue])
self.assertEqual(list(map(int, Color)), [1, 2, 3])
def test_ordered_mixin(self):
class OrderedEnum(Enum):
def __ge__(self, other):
if self.__class__ is other.__class__:
return self._value >= other._value
return NotImplemented
def __gt__(self, other):
if self.__class__ is other.__class__:
return self._value > other._value
return NotImplemented
def __le__(self, other):
if self.__class__ is other.__class__:
return self._value <= other._value
return NotImplemented
def __lt__(self, other):
if self.__class__ is other.__class__:
return self._value < other._value
return NotImplemented
class Grade(OrderedEnum):
A = 5
B = 4
C = 3
D = 2
F = 1
self.assertGreater(Grade.A, Grade.B)
self.assertLessEqual(Grade.F, Grade.C)
self.assertLess(Grade.D, Grade.A)
self.assertGreaterEqual(Grade.B, Grade.B)
def test_extending2(self):
class Shade(Enum):
def shade(self):
print(self.name)
class Color(Shade):
red = 1
green = 2
blue = 3
with self.assertRaises(TypeError):
class MoreColor(Color):
cyan = 4
magenta = 5
yellow = 6
def test_extending3(self):
class Shade(Enum):
def shade(self):
return self.name
class Color(Shade):
def hex(self):
return '%s hexlified!' % self.value
class MoreColor(Color):
cyan = 4
magenta = 5
yellow = 6
self.assertEqual(MoreColor.magenta.hex(), '5 hexlified!')
def test_no_duplicates(self):
class UniqueEnum(Enum):
def __init__(self, *args):
cls = self.__class__
if any(self.value == e.value for e in cls):
a = self.name
e = cls(self.value).name
raise ValueError(
"aliases not allowed in UniqueEnum: %r --> %r"
% (a, e)
)
class Color(UniqueEnum):
red = 1
green = 2
blue = 3
with self.assertRaises(ValueError):
class Color(UniqueEnum):
red = 1
green = 2
blue = 3
grene = 2
def test_init(self):
class Planet(Enum):
MERCURY = (3.303e+23, 2.4397e6)
VENUS = (4.869e+24, 6.0518e6)
EARTH = (5.976e+24, 6.37814e6)
MARS = (6.421e+23, 3.3972e6)
JUPITER = (1.9e+27, 7.1492e7)
SATURN = (5.688e+26, 6.0268e7)
URANUS = (8.686e+25, 2.5559e7)
NEPTUNE = (1.024e+26, 2.4746e7)
def __init__(self, mass, radius):
self.mass = mass # in kilograms
self.radius = radius # in meters
@property
def surface_gravity(self):
# universal gravitational constant (m3 kg-1 s-2)
G = 6.67300E-11
return G * self.mass / (self.radius * self.radius)
self.assertEqual(round(Planet.EARTH.surface_gravity, 2), 9.80)
self.assertEqual(Planet.EARTH.value, (5.976e+24, 6.37814e6))
if __name__ == '__main__':
unittest.main()

2
Misc/NEWS
View File

@ -381,6 +381,8 @@ Library
- Implement PEP 443 "Single-dispatch generic functions".
- Implement PEP 435 "Adding an Enum type to the Python standard library".
Tests
-----