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Close #18908: Keep Enum docs in their own section. Patch by Elazar Gershuni.
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1 changed files with 67 additions and 58 deletions
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@ -36,11 +36,15 @@ follows::
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... red = 1
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... red = 1
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... green = 2
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... green = 2
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... blue = 3
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... blue = 3
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...
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**A note on nomenclature**: we call :class:`Color` an *enumeration* (or *enum*)
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..note: Nomenclature
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and :attr:`Color.red`, :attr:`Color.green` are *enumeration members* (or
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- The class :class:`Color` is an *enumeration* (or *enum*)
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*enum members*). Enumeration members also have *values* (the value of
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- The attributes :attr:`Color.red`, :attr:`Color.green`, etc., are
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:attr:`Color.red` is ``1``, etc.)
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*enumeration members* (or *enum members*).
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- The enum members have *names* and *values* (the name of
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:attr:`Color.red` is ``red``, the value of :attr:`Color.blue` is
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``3``, etc.)
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Enumeration members have human readable string representations::
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Enumeration members have human readable string representations::
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@ -151,7 +155,7 @@ return A::
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Ensuring unique enumeration values
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Ensuring unique enumeration values
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==================================
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----------------------------------
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By default, enumerations allow multiple names as aliases for the same value.
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By default, enumerations allow multiple names as aliases for the same value.
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When this behavior isn't desired, the following decorator can be used to
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When this behavior isn't desired, the following decorator can be used to
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@ -170,13 +174,14 @@ found :exc:`ValueError` is raised with the details::
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... two = 2
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... two = 2
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... three = 3
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... three = 3
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... four = 3
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... four = 3
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...
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Traceback (most recent call last):
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Traceback (most recent call last):
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...
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...
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ValueError: duplicate values found in <enum 'Mistake'>: four -> three
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ValueError: duplicate values found in <enum 'Mistake'>: four -> three
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Iteration
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Iteration
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=========
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---------
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Iterating over the members of an enum does not provide the aliases::
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Iterating over the members of an enum does not provide the aliases::
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@ -266,6 +271,7 @@ usual. If we have this enumeration::
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... def favorite_mood(cls):
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... def favorite_mood(cls):
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... # cls here is the enumeration
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... # cls here is the enumeration
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... return cls.happy
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... return cls.happy
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...
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Then::
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Then::
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@ -295,6 +301,7 @@ any members. So this is forbidden::
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>>> class MoreColor(Color):
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>>> class MoreColor(Color):
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... pink = 17
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... pink = 17
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...
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Traceback (most recent call last):
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Traceback (most recent call last):
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...
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...
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TypeError: Cannot extend enumerations
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TypeError: Cannot extend enumerations
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@ -367,6 +374,7 @@ assignment to :class:`Animal` is equivalent to::
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... bee = 2
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... bee = 2
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... cat = 3
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... cat = 3
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... dog = 4
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... dog = 4
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...
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The reason for defaulting to ``1`` as the starting number and not ``0`` is
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The reason for defaulting to ``1`` as the starting number and not ``0`` is
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that ``0`` is ``False`` in a boolean sense, but enum members all evaluate
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that ``0`` is ``False`` in a boolean sense, but enum members all evaluate
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@ -381,10 +389,10 @@ The solution is to specify the module name explicitly as follows::
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>>> Animals = Enum('Animals', 'ant bee cat dog', module=__name__)
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>>> Animals = Enum('Animals', 'ant bee cat dog', module=__name__)
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Derived Enumerations
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Derived Enumerations
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====================
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--------------------
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IntEnum
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IntEnum
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-------
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^^^^^^^
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A variation of :class:`Enum` is provided which is also a subclass of
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A variation of :class:`Enum` is provided which is also a subclass of
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:class:`int`. Members of an :class:`IntEnum` can be compared to integers;
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:class:`int`. Members of an :class:`IntEnum` can be compared to integers;
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@ -439,7 +447,7 @@ that still expects integers.
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Others
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Others
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------
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^^^^^^
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While :class:`IntEnum` is part of the :mod:`enum` module, it would be very
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While :class:`IntEnum` is part of the :mod:`enum` module, it would be very
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simple to implement independently::
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simple to implement independently::
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@ -472,7 +480,7 @@ Some rules:
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Interesting examples
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Interesting examples
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====================
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--------------------
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While :class:`Enum` and :class:`IntEnum` are expected to cover the majority of
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While :class:`Enum` and :class:`IntEnum` are expected to cover the majority of
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use-cases, they cannot cover them all. Here are recipes for some different
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use-cases, they cannot cover them all. Here are recipes for some different
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@ -481,7 +489,7 @@ one's own.
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AutoNumber
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AutoNumber
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----------
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^^^^^^^^^^
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Avoids having to specify the value for each enumeration member::
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Avoids having to specify the value for each enumeration member::
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@ -502,7 +510,7 @@ Avoids having to specify the value for each enumeration member::
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OrderedEnum
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OrderedEnum
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-----------
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^^^^^^^^^^^
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An ordered enumeration that is not based on :class:`IntEnum` and so maintains
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An ordered enumeration that is not based on :class:`IntEnum` and so maintains
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the normal :class:`Enum` invariants (such as not being comparable to other
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the normal :class:`Enum` invariants (such as not being comparable to other
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@ -538,7 +546,7 @@ enumerations)::
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DuplicateFreeEnum
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DuplicateFreeEnum
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-----------------
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^^^^^^^^^^^^^^^^^
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Raises an error if a duplicate member name is found instead of creating an
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Raises an error if a duplicate member name is found instead of creating an
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alias::
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alias::
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@ -558,6 +566,7 @@ alias::
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... green = 2
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... green = 2
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... blue = 3
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... blue = 3
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... grene = 2
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... grene = 2
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...
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Traceback (most recent call last):
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Traceback (most recent call last):
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...
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...
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ValueError: aliases not allowed in DuplicateFreeEnum: 'grene' --> 'green'
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ValueError: aliases not allowed in DuplicateFreeEnum: 'grene' --> 'green'
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@ -570,7 +579,7 @@ alias::
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Planet
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Planet
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------
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^^^^^^
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If :meth:`__new__` or :meth:`__init__` is defined the value of the enum member
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If :meth:`__new__` or :meth:`__init__` is defined the value of the enum member
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will be passed to those methods::
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will be passed to those methods::
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