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:mod:`enum` --- Support for enumerations
========================================
.. module:: enum
:synopsis: Implementation of an enumeration class.
.. moduleauthor:: Ethan Furman <ethan@stoneleaf.us>
.. sectionauthor:: Barry Warsaw <barry@python.org>
.. sectionauthor:: Eli Bendersky <eliben@gmail.com>
.. sectionauthor:: Ethan Furman <ethan@stoneleaf.us>
2013-12-20 15:20:49 -04:00
.. versionadded:: 3.4
**Source code:** :source:`Lib/enum.py`
.. sidebar:: Important
This page contains the API reference information. For tutorial
information and discussion of more advanced topics, see
* :ref:`Basic Tutorial <enum-basic-tutorial>`
* :ref:`Advanced Tutorial <enum-advanced-tutorial>`
* :ref:`Enum Cookbook <enum-cookbook>`
---------------
An enumeration:
* is a set of symbolic names (members) bound to unique values
* can be iterated over to return its members in definition order
* uses *call* syntax to return members by value
* uses *index* syntax to return members by name
Enumerations are created either by using :keyword:`class` syntax, or by
using function-call syntax::
>>> from enum import Enum
>>> # class syntax
>>> class Color(Enum):
... RED = 1
... GREEN = 2
... BLUE = 3
>>> # functional syntax
>>> Color = Enum('Color', ['RED', 'GREEN', 'BLUE'])
Even though we can use :keyword:`class` syntax to create Enums, Enums
are not normal Python classes. See
:ref:`How are Enums different? <enum-class-differences>` for more details.
.. note:: Nomenclature
- The class :class:`Color` is an *enumeration* (or *enum*)
- The attributes :attr:`Color.RED`, :attr:`Color.GREEN`, etc., are
*enumeration members* (or *members*) and are functionally constants.
- The enum members have *names* and *values* (the name of
:attr:`Color.RED` is ``RED``, the value of :attr:`Color.BLUE` is
``3``, etc.)
---------------
Module Contents
---------------
:class:`EnumType`
The ``type`` for Enum and its subclasses.
:class:`Enum`
Base class for creating enumerated constants.
:class:`IntEnum`
Base class for creating enumerated constants that are also
subclasses of :class:`int`. (`Notes`_)
:class:`StrEnum`
Base class for creating enumerated constants that are also
subclasses of :class:`str`. (`Notes`_)
:class:`Flag`
Base class for creating enumerated constants that can be combined using
the bitwise operations without losing their :class:`Flag` membership.
:class:`IntFlag`
Base class for creating enumerated constants that can be combined using
the bitwise operators without losing their :class:`IntFlag` membership.
:class:`IntFlag` members are also subclasses of :class:`int`. (`Notes`_)
:class:`EnumCheck`
An enumeration with the values ``CONTINUOUS``, ``NAMED_FLAGS``, and
``UNIQUE``, for use with :func:`verify` to ensure various constraints
are met by a given enumeration.
:class:`FlagBoundary`
An enumeration with the values ``STRICT``, ``CONFORM``, ``EJECT``, and
``KEEP`` which allows for more fine-grained control over how invalid values
are dealt with in an enumeration.
:class:`auto`
Instances are replaced with an appropriate value for Enum members.
:class:`StrEnum` defaults to the lower-cased version of the member name,
while other Enums default to 1 and increase from there.
:func:`~enum.property`
Allows :class:`Enum` members to have attributes without conflicting with
member names.
:func:`unique`
Enum class decorator that ensures only one name is bound to any one value.
:func:`verify`
Enum class decorator that checks user-selectable constraints on an
enumeration.
:func:`member`
Make ``obj`` a member. Can be used as a decorator.
:func:`nonmember`
Do not make ``obj`` a member. Can be used as a decorator.
.. versionadded:: 3.6 ``Flag``, ``IntFlag``, ``auto``
.. versionadded:: 3.11 ``StrEnum``, ``EnumCheck``, ``FlagBoundary``, ``property``
.. versionadded:: 3.11 ``member``, ``nonmember``
---------------
Data Types
----------
.. class:: EnumType
*EnumType* is the :term:`metaclass` for *enum* enumerations. It is possible
to subclass *EnumType* -- see :ref:`Subclassing EnumType <enumtype-examples>`
for details.
*EnumType* is responsible for setting the correct :meth:`__repr__`,
:meth:`__str__`, :meth:`__format__`, and :meth:`__reduce__` methods on the
final *enum*, as well as creating the enum members, properly handling
duplicates, providing iteration over the enum class, etc.
.. method:: EnumType.__contains__(cls, member)
Returns ``True`` if member belongs to the ``cls``::
>>> some_var = Color.RED
>>> some_var in Color
True
.. note::
In Python 3.12 it will be possible to check for member values and not
just members; until then, a ``TypeError`` will be raised if a
non-Enum-member is used in a containment check.
.. method:: EnumType.__dir__(cls)
Returns ``['__class__', '__doc__', '__members__', '__module__']`` and the
names of the members in *cls*::
>>> dir(Color)
['BLUE', 'GREEN', 'RED', '__class__', '__contains__', '__doc__', '__getitem__', '__init_subclass__', '__iter__', '__len__', '__members__', '__module__', '__name__', '__qualname__']
.. method:: EnumType.__getattr__(cls, name)
Returns the Enum member in *cls* matching *name*, or raises an :exc:`AttributeError`::
>>> Color.GREEN
<Color.GREEN: 2>
.. method:: EnumType.__getitem__(cls, name)
Returns the Enum member in *cls* matching *name*, or raises an :exc:`KeyError`::
>>> Color['BLUE']
<Color.BLUE: 3>
.. method:: EnumType.__iter__(cls)
Returns each member in *cls* in definition order::
>>> list(Color)
[<Color.RED: 1>, <Color.GREEN: 2>, <Color.BLUE: 3>]
.. method:: EnumType.__len__(cls)
Returns the number of member in *cls*::
>>> len(Color)
3
.. method:: EnumType.__reversed__(cls)
Returns each member in *cls* in reverse definition order::
>>> list(reversed(Color))
[<Color.BLUE: 3>, <Color.GREEN: 2>, <Color.RED: 1>]
.. class:: Enum
*Enum* is the base class for all *enum* enumerations.
.. attribute:: Enum.name
The name used to define the ``Enum`` member::
>>> Color.BLUE.name
'BLUE'
.. attribute:: Enum.value
The value given to the ``Enum`` member::
>>> Color.RED.value
1
.. note:: Enum member values
Member values can be anything: :class:`int`, :class:`str`, etc.. If
the exact value is unimportant you may use :class:`auto` instances and an
appropriate value will be chosen for you. Care must be taken if you mix
:class:`auto` with other values.
.. attribute:: Enum._ignore_
``_ignore_`` is only used during creation and is removed from the
enumeration once creation is complete.
``_ignore_`` is a list of names that will not become members, and whose
names will also be removed from the completed enumeration. See
:ref:`TimePeriod <enum-time-period>` for an example.
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
.. method:: Enum.__call__(cls, value, names=None, \*, module=None, qualname=None, type=None, start=1, boundary=None)
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
This method is called in two different ways:
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
* to look up an existing member:
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
:cls: The enum class being called.
:value: The value to lookup.
* to use the ``cls`` enum to create a new enum:
:cls: The enum class being called.
:value: The name of the new Enum to create.
:names: The names/values of the members for the new Enum.
:module: The name of the module the new Enum is created in.
:qualname: The actual location in the module where this Enum can be found.
:type: A mix-in type for the new Enum.
:start: The first integer value for the Enum (used by :class:`auto`)
:boundary: How to handle out-of-range values from bit operations (:class:`Flag` only)
.. method:: Enum.__dir__(self)
Returns ``['__class__', '__doc__', '__module__', 'name', 'value']`` and
any public methods defined on *self.__class__*::
>>> from datetime import date
>>> class Weekday(Enum):
... MONDAY = 1
... TUESDAY = 2
... WEDNESDAY = 3
... THURSDAY = 4
... FRIDAY = 5
... SATURDAY = 6
... SUNDAY = 7
... @classmethod
... def today(cls):
... print('today is %s' % cls(date.today().isoweekday()).name)
>>> dir(Weekday.SATURDAY)
['__class__', '__doc__', '__eq__', '__hash__', '__module__', 'name', 'today', 'value']
.. method:: Enum._generate_next_value_(name, start, count, last_values)
:name: The name of the member being defined (e.g. 'RED').
:start: The start value for the Enum; the default is 1.
:count: The number of members currently defined, not including this one.
:last_values: A list of the previous values.
A *staticmethod* that is used to determine the next value returned by
:class:`auto`::
>>> from enum import auto
>>> class PowersOfThree(Enum):
... @staticmethod
... def _generate_next_value_(name, start, count, last_values):
... return (count + 1) * 3
... FIRST = auto()
... SECOND = auto()
>>> PowersOfThree.SECOND.value
6
.. method:: Enum.__init_subclass__(cls, \**kwds)
A *classmethod* that is used to further configure subsequent subclasses.
By default, does nothing.
.. method:: Enum._missing_(cls, value)
A *classmethod* for looking up values not found in *cls*. By default it
does nothing, but can be overridden to implement custom search behavior::
>>> from enum import StrEnum
>>> class Build(StrEnum):
... DEBUG = auto()
... OPTIMIZED = auto()
... @classmethod
... def _missing_(cls, value):
... value = value.lower()
... for member in cls:
... if member.value == value:
... return member
... return None
>>> Build.DEBUG.value
'debug'
>>> Build('deBUG')
<Build.DEBUG: 'debug'>
.. method:: Enum.__repr__(self)
Returns the string used for *repr()* calls. By default, returns the
*Enum* name, member name, and value, but can be overridden::
>>> class OtherStyle(Enum):
... ALTERNATE = auto()
... OTHER = auto()
... SOMETHING_ELSE = auto()
... def __repr__(self):
... cls_name = self.__class__.__name__
... return f'{cls_name}.{self.name}'
>>> OtherStyle.ALTERNATE, str(OtherStyle.ALTERNATE), f"{OtherStyle.ALTERNATE}"
(OtherStyle.ALTERNATE, 'OtherStyle.ALTERNATE', 'OtherStyle.ALTERNATE')
.. method:: Enum.__str__(self)
Returns the string used for *str()* calls. By default, returns the
*Enum* name and member name, but can be overridden::
>>> class OtherStyle(Enum):
... ALTERNATE = auto()
... OTHER = auto()
... SOMETHING_ELSE = auto()
... def __str__(self):
... return f'{self.name}'
>>> OtherStyle.ALTERNATE, str(OtherStyle.ALTERNATE), f"{OtherStyle.ALTERNATE}"
(<OtherStyle.ALTERNATE: 1>, 'ALTERNATE', 'ALTERNATE')
.. method:: Enum.__format__(self)
Returns the string used for *format()* and *f-string* calls. By default,
returns :meth:`__str__` returns, but can be overridden::
>>> class OtherStyle(Enum):
... ALTERNATE = auto()
... OTHER = auto()
... SOMETHING_ELSE = auto()
... def __format__(self, spec):
... return f'{self.name}'
>>> OtherStyle.ALTERNATE, str(OtherStyle.ALTERNATE), f"{OtherStyle.ALTERNATE}"
(<OtherStyle.ALTERNATE: 1>, 'OtherStyle.ALTERNATE', 'ALTERNATE')
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
.. note::
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
Using :class:`auto` with :class:`Enum` results in integers of increasing value,
starting with ``1``.
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
.. class:: IntEnum
*IntEnum* is the same as *Enum*, but its members are also integers and can be
used anywhere that an integer can be used. If any integer operation is performed
with an *IntEnum* member, the resulting value loses its enumeration status.
>>> from enum import IntEnum
>>> class Numbers(IntEnum):
... ONE = 1
... TWO = 2
... THREE = 3
>>> Numbers.THREE
<Numbers.THREE: 3>
>>> Numbers.ONE + Numbers.TWO
3
>>> Numbers.THREE + 5
8
>>> Numbers.THREE == 3
True
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
.. note::
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
Using :class:`auto` with :class:`IntEnum` results in integers of increasing
value, starting with ``1``.
.. versionchanged:: 3.11 :meth:`__str__` is now :func:`int.__str__` to
better support the *replacement of existing constants* use-case.
:meth:`__format__` was already :func:`int.__format__` for that same reason.
.. class:: StrEnum
*StrEnum* is the same as *Enum*, but its members are also strings and can be used
in most of the same places that a string can be used. The result of any string
operation performed on or with a *StrEnum* member is not part of the enumeration.
.. note:: There are places in the stdlib that check for an exact :class:`str`
instead of a :class:`str` subclass (i.e. ``type(unknown) == str``
instead of ``isinstance(str, unknown)``), and in those locations you
will need to use ``str(StrEnum.member)``.
.. note::
Using :class:`auto` with :class:`StrEnum` results in the lower-cased member
name as the value.
.. note:: :meth:`__str__` is :func:`str.__str__` to better support the
*replacement of existing constants* use-case. :meth:`__format__` is likewise
:func:`str.__format__` for that same reason.
.. versionadded:: 3.11
.. class:: Flag
*Flag* members support the bitwise operators ``&`` (*AND*), ``|`` (*OR*),
``^`` (*XOR*), and ``~`` (*INVERT*); the results of those operators are members
of the enumeration.
.. method:: __contains__(self, value)
Returns *True* if value is in self::
>>> from enum import Flag, auto
>>> class Color(Flag):
... RED = auto()
... GREEN = auto()
... BLUE = auto()
>>> purple = Color.RED | Color.BLUE
>>> white = Color.RED | Color.GREEN | Color.BLUE
>>> Color.GREEN in purple
False
>>> Color.GREEN in white
True
>>> purple in white
True
>>> white in purple
False
.. method:: __iter__(self):
Returns all contained members::
>>> list(Color.RED)
[<Color.RED: 1>]
>>> list(purple)
[<Color.RED: 1>, <Color.BLUE: 4>]
.. method:: __len__(self):
Returns number of members in flag::
>>> len(Color.GREEN)
1
>>> len(white)
3
.. method:: __bool__(self):
Returns *True* if any members in flag, *False* otherwise::
>>> bool(Color.GREEN)
True
>>> bool(white)
True
>>> black = Color(0)
>>> bool(black)
False
.. method:: __or__(self, other)
Returns current flag binary or'ed with other::
>>> Color.RED | Color.GREEN
<Color.RED|GREEN: 3>
.. method:: __and__(self, other)
Returns current flag binary and'ed with other::
>>> purple & white
<Color.RED|BLUE: 5>
>>> purple & Color.GREEN
<Color: 0>
.. method:: __xor__(self, other)
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
Returns current flag binary xor'ed with other::
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
>>> purple ^ white
<Color.GREEN: 2>
>>> purple ^ Color.GREEN
<Color.RED|GREEN|BLUE: 7>
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
.. method:: __invert__(self):
Returns all the flags in *type(self)* that are not in self::
>>> ~white
<Color: 0>
>>> ~purple
<Color.GREEN: 2>
>>> ~Color.RED
<Color.GREEN|BLUE: 6>
.. method:: _numeric_repr_
Function used to format any remaining unnamed numeric values. Default is
the value's repr; common choices are :func:`hex` and :func:`oct`.
.. note::
Using :class:`auto` with :class:`Flag` results in integers that are powers
of two, starting with ``1``.
.. versionchanged:: 3.11 The *repr()* of zero-valued flags has changed. It
is now::
>>> Color(0) # doctest: +SKIP
<Color: 0>
.. class:: IntFlag
*IntFlag* is the same as *Flag*, but its members are also integers and can be
used anywhere that an integer can be used.
>>> from enum import IntFlag, auto
>>> class Color(IntFlag):
... RED = auto()
... GREEN = auto()
... BLUE = auto()
>>> Color.RED & 2
<Color: 0>
>>> Color.RED | 2
<Color.RED|GREEN: 3>
If any integer operation is performed with an *IntFlag* member, the result is
not an *IntFlag*::
>>> Color.RED + 2
3
If a *Flag* operation is performed with an *IntFlag* member and:
* the result is a valid *IntFlag*: an *IntFlag* is returned
* the result is not a valid *IntFlag*: the result depends on the *FlagBoundary* setting
The *repr()* of unnamed zero-valued flags has changed. It is now:
>>> Color(0)
<Color: 0>
.. note::
Using :class:`auto` with :class:`IntFlag` results in integers that are powers
of two, starting with ``1``.
.. versionchanged:: 3.11 :meth:`__str__` is now :func:`int.__str__` to
better support the *replacement of existing constants* use-case.
:meth:`__format__` was already :func:`int.__format__` for that same reason.
.. class:: EnumCheck
*EnumCheck* contains the options used by the :func:`verify` decorator to ensure
various constraints; failed constraints result in a :exc:`ValueError`.
.. attribute:: UNIQUE
Ensure that each value has only one name::
>>> from enum import Enum, verify, UNIQUE
>>> @verify(UNIQUE)
... class Color(Enum):
... RED = 1
... GREEN = 2
... BLUE = 3
... CRIMSON = 1
Traceback (most recent call last):
...
ValueError: aliases found in <enum 'Color'>: CRIMSON -> RED
.. attribute:: CONTINUOUS
Ensure that there are no missing values between the lowest-valued member
and the highest-valued member::
>>> from enum import Enum, verify, CONTINUOUS
>>> @verify(CONTINUOUS)
... class Color(Enum):
... RED = 1
... GREEN = 2
... BLUE = 5
Traceback (most recent call last):
...
ValueError: invalid enum 'Color': missing values 3, 4
.. attribute:: NAMED_FLAGS
Ensure that any flag groups/masks contain only named flags -- useful when
values are specified instead of being generated by :func:`auto`
>>> from enum import Flag, verify, NAMED_FLAGS
>>> @verify(NAMED_FLAGS)
... class Color(Flag):
... RED = 1
... GREEN = 2
... BLUE = 4
... WHITE = 15
... NEON = 31
Traceback (most recent call last):
...
ValueError: invalid Flag 'Color': aliases WHITE and NEON are missing combined values of 0x18 [use enum.show_flag_values(value) for details]
.. note::
CONTINUOUS and NAMED_FLAGS are designed to work with integer-valued members.
.. versionadded:: 3.11
.. class:: FlagBoundary
*FlagBoundary* controls how out-of-range values are handled in *Flag* and its
subclasses.
2016-08-20 04:00:52 -03:00
.. attribute:: STRICT
Out-of-range values cause a :exc:`ValueError` to be raised. This is the
default for :class:`Flag`::
>>> from enum import Flag, STRICT
>>> class StrictFlag(Flag, boundary=STRICT):
... RED = auto()
... GREEN = auto()
... BLUE = auto()
>>> StrictFlag(2**2 + 2**4)
Traceback (most recent call last):
...
ValueError: <flag 'StrictFlag'> invalid value 20
given 0b0 10100
allowed 0b0 00111
.. attribute:: CONFORM
Out-of-range values have invalid values removed, leaving a valid *Flag*
value::
>>> from enum import Flag, CONFORM
>>> class ConformFlag(Flag, boundary=CONFORM):
... RED = auto()
... GREEN = auto()
... BLUE = auto()
>>> ConformFlag(2**2 + 2**4)
<ConformFlag.BLUE: 4>
.. attribute:: EJECT
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
Out-of-range values lose their *Flag* membership and revert to :class:`int`.
This is the default for :class:`IntFlag`::
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
>>> from enum import Flag, EJECT
>>> class EjectFlag(Flag, boundary=EJECT):
... RED = auto()
... GREEN = auto()
... BLUE = auto()
>>> EjectFlag(2**2 + 2**4)
20
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
.. attribute:: KEEP
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
Out-of-range values are kept, and the *Flag* membership is kept. This is
used for some stdlib flags:
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
>>> from enum import Flag, KEEP
>>> class KeepFlag(Flag, boundary=KEEP):
... RED = auto()
... GREEN = auto()
... BLUE = auto()
>>> KeepFlag(2**2 + 2**4)
<KeepFlag.BLUE|16: 20>
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
.. versionadded:: 3.11
---------------
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
Supported ``__dunder__`` names
""""""""""""""""""""""""""""""
:attr:`__members__` is a read-only ordered mapping of ``member_name``:``member``
items. It is only available on the class.
:meth:`__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
.. note::
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, regardless of the last value seen.
.. versionadded:: 3.6 ``_missing_``, ``_order_``, ``_generate_next_value_``
.. versionadded:: 3.7 ``_ignore_``
---------------
Utilities and Decorators
------------------------
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
.. class:: auto
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
*auto* can be used in place of a value. If used, the *Enum* machinery will
call an *Enum*'s :meth:`_generate_next_value_` to get an appropriate value.
For *Enum* and *IntEnum* that appropriate value will be the last value plus
one; for *Flag* and *IntFlag* it will be the first power-of-two greater
than the last value; for *StrEnum* it will be the lower-cased version of the
member's name.
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
``_generate_next_value_`` can be overridden to customize the values used by
*auto*.
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
.. decorator:: property
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
A decorator similar to the built-in *property*, but specifically for
enumerations. It allows member attributes to have the same names as members
themselves.
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
.. note:: the *property* and the member must be defined in separate classes;
for example, the *value* and *name* attributes are defined in the
*Enum* class, and *Enum* subclasses can define members with the
names ``value`` and ``name``.
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
.. versionadded:: 3.11
.. decorator:: unique
bpo-38250: [Enum] single-bit flags are canonical (GH-24215) Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags. Iterating, repr(), and str() show members in definition order. When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired: >>> class Test(Flag, boundary=CONFORM): ... ONE = 1 ... TWO = 2 ... >>> Test(5) <Test.ONE: 1> Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits. Iteration is now in member definition order. If member definition order matches increasing value order, then a more efficient method of flag decomposition is used; otherwise, sort() is called on the results of that method to get definition order. ``re`` module: repr() has been modified to support as closely as possible its previous output; the big difference is that inverted flags cannot be output as before because the inversion operation now always returns the comparable positive result; i.e. re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG) in both of the above terms, the ``value`` is 282. re's tests have been updated to reflect the modifications to repr().
2021-01-25 18:26:19 -04:00
A :keyword:`class` decorator specifically for enumerations. It searches an
enumeration's :attr:`__members__`, gathering any aliases it finds; if any are
found :exc:`ValueError` is raised with the details::
>>> from enum import Enum, unique
>>> @unique
... class Mistake(Enum):
... ONE = 1
... TWO = 2
... THREE = 3
... FOUR = 3
...
Traceback (most recent call last):
...
ValueError: duplicate values found in <enum 'Mistake'>: FOUR -> THREE
.. decorator:: verify
A :keyword:`class` decorator specifically for enumerations. Members from
:class:`EnumCheck` are used to specify which constraints should be checked
on the decorated enumeration.
.. versionadded:: 3.11
.. decorator:: member
A decorator for use in enums: its target will become a member.
.. versionadded:: 3.11
.. decorator:: nonmember
A decorator for use in enums: its target will not become a member.
.. versionadded:: 3.11
---------------
Notes
-----
:class:`IntEnum`, :class:`StrEnum`, and :class:`IntFlag`
These three enum types are designed to be drop-in replacements for existing
integer- and string-based values; as such, they have extra limitations:
- ``__str__`` uses the value and not the name of the enum member
- ``__format__``, because it uses ``__str__``, will also use the value of
the enum member instead of its name
If you do not need/want those limitations, you can either create your own
base class by mixing in the ``int`` or ``str`` type yourself::
>>> from enum import Enum
>>> class MyIntEnum(int, Enum):
... pass
or you can reassign the appropriate :meth:`str`, etc., in your enum::
>>> from enum import IntEnum
>>> class MyIntEnum(IntEnum):
... __str__ = IntEnum.__str__