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authorEthan Furman <ethan@stoneleaf.us>2016-11-21 17:22:05 (GMT)
committerEthan Furman <ethan@stoneleaf.us>2016-11-21 17:22:05 (GMT)
commit23bb6f48ea30e805b558a4e03849c362029ca7c4 (patch)
tree8109cb1787acc3949014320885ceaa234c37fa1b /Doc
parent64a6861b0f113002763407159fe287a5c38a8fa2 (diff)
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close issue28172: Change all example enum member names to uppercase, per Guido; patch by Chris Angelico.
Diffstat (limited to 'Doc')
-rw-r--r--Doc/library/enum.rst345
1 files changed, 173 insertions, 172 deletions
diff --git a/Doc/library/enum.rst b/Doc/library/enum.rst
index 87aa8b1..ddcc286 100644
--- a/Doc/library/enum.rst
+++ b/Doc/library/enum.rst
@@ -70,9 +70,9 @@ follows::
>>> from enum import Enum
>>> class Color(Enum):
- ... red = 1
- ... green = 2
- ... blue = 3
+ ... RED = 1
+ ... GREEN = 2
+ ... BLUE = 3
...
.. note:: Enum member values
@@ -85,10 +85,10 @@ follows::
.. note:: Nomenclature
- The class :class:`Color` is an *enumeration* (or *enum*)
- - The attributes :attr:`Color.red`, :attr:`Color.green`, etc., are
- *enumeration members* (or *enum members*).
+ - The attributes :attr:`Color.RED`, :attr:`Color.GREEN`, etc., are
+ *enumeration members* (or *enum 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
+ :attr:`Color.RED` is ``RED``, the value of :attr:`Color.BLUE` is
``3``, etc.)
.. note::
@@ -99,49 +99,49 @@ follows::
Enumeration members have human readable string representations::
- >>> print(Color.red)
- Color.red
+ >>> print(Color.RED)
+ Color.RED
...while their ``repr`` has more information::
- >>> print(repr(Color.red))
- <Color.red: 1>
+ >>> print(repr(Color.RED))
+ <Color.RED: 1>
The *type* of an enumeration member is the enumeration it belongs to::
- >>> type(Color.red)
+ >>> type(Color.RED)
<enum 'Color'>
- >>> isinstance(Color.green, Color)
+ >>> isinstance(Color.GREEN, Color)
True
>>>
Enum members also have a property that contains just their item name::
- >>> print(Color.red.name)
- red
+ >>> print(Color.RED.name)
+ RED
Enumerations support iteration, in definition order::
>>> class Shake(Enum):
- ... vanilla = 7
- ... chocolate = 4
- ... cookies = 9
- ... mint = 3
+ ... VANILLA = 7
+ ... CHOCOLATE = 4
+ ... COOKIES = 9
+ ... MINT = 3
...
>>> for shake in Shake:
... print(shake)
...
- Shake.vanilla
- Shake.chocolate
- Shake.cookies
- Shake.mint
+ 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'}
+ >>> apples[Color.RED] = 'red delicious'
+ >>> apples[Color.GREEN] = 'granny smith'
+ >>> apples == {Color.RED: 'red delicious', Color.GREEN: 'granny smith'}
True
@@ -149,26 +149,26 @@ Programmatic access to enumeration members and their attributes
---------------------------------------------------------------
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
+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.RED: 1>
>>> Color(3)
- <Color.blue: 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>
+ >>> Color['RED']
+ <Color.RED: 1>
+ >>> Color['GREEN']
+ <Color.GREEN: 2>
If you have an enum member and need its :attr:`name` or :attr:`value`::
- >>> member = Color.red
+ >>> member = Color.RED
>>> member.name
- 'red'
+ 'RED'
>>> member.value
1
@@ -179,12 +179,12 @@ Duplicating enum members and values
Having two enum members with the same name is invalid::
>>> class Shape(Enum):
- ... square = 2
- ... square = 3
+ ... SQUARE = 2
+ ... SQUARE = 3
...
Traceback (most recent call last):
...
- TypeError: Attempted to reuse key: 'square'
+ 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
@@ -192,17 +192,17 @@ 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
+ ... SQUARE = 2
+ ... DIAMOND = 1
+ ... CIRCLE = 3
+ ... ALIAS_FOR_SQUARE = 2
...
- >>> Shape.square
- <Shape.square: 2>
- >>> Shape.alias_for_square
- <Shape.square: 2>
+ >>> Shape.SQUARE
+ <Shape.SQUARE: 2>
+ >>> Shape.ALIAS_FOR_SQUARE
+ <Shape.SQUARE: 2>
>>> Shape(2)
- <Shape.square: 2>
+ <Shape.SQUARE: 2>
.. note::
@@ -227,14 +227,14 @@ 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
+ ... ONE = 1
+ ... TWO = 2
+ ... THREE = 3
+ ... FOUR = 3
...
Traceback (most recent call last):
...
- ValueError: duplicate values found in <enum 'Mistake'>: four -> three
+ ValueError: duplicate values found in <enum 'Mistake'>: FOUR -> THREE
Using automatic values
@@ -244,12 +244,12 @@ If the exact value is unimportant you can use :class:`auto`::
>>> from enum import Enum, auto
>>> class Color(Enum):
- ... red = auto()
- ... blue = auto()
- ... green = auto()
+ ... RED = auto()
+ ... BLUE = auto()
+ ... GREEN = auto()
...
>>> list(Color)
- [<Color.red: 1>, <Color.blue: 2>, <Color.green: 3>]
+ [<Color.RED: 1>, <Color.BLUE: 2>, <Color.GREEN: 3>]
The values are chosen by :func:`_generate_next_value_`, which can be
overridden::
@@ -259,13 +259,13 @@ overridden::
... return name
...
>>> class Ordinal(AutoName):
- ... north = auto()
- ... south = auto()
- ... east = auto()
- ... west = auto()
+ ... NORTH = auto()
+ ... SOUTH = auto()
+ ... EAST = auto()
+ ... WEST = auto()
...
>>> list(Ordinal)
- [<Ordinal.north: 'north'>, <Ordinal.south: 'south'>, <Ordinal.east: 'east'>, <Ordinal.west: 'west'>]
+ [<Ordinal.NORTH: 'NORTH'>, <Ordinal.SOUTH: 'SOUTH'>, <Ordinal.EAST: 'EAST'>, <Ordinal.WEST: 'WEST'>]
.. note::
@@ -279,7 +279,7 @@ Iteration
Iterating over the members of an enum does not provide the aliases::
>>> list(Shape)
- [<Shape.square: 2>, <Shape.diamond: 1>, <Shape.circle: 3>]
+ [<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
@@ -288,16 +288,16 @@ 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>)
+ ('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']
+ ['ALIAS_FOR_SQUARE']
Comparisons
@@ -305,35 +305,35 @@ Comparisons
Enumeration members are compared by identity::
- >>> Color.red is Color.red
+ >>> Color.RED is Color.RED
True
- >>> Color.red is Color.blue
+ >>> Color.RED is Color.BLUE
False
- >>> Color.red is not Color.blue
+ >>> 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
+ >>> Color.RED < Color.BLUE
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: '<' not supported between instances of 'Color' and 'Color'
Equality comparisons are defined though::
- >>> Color.blue == Color.red
+ >>> Color.BLUE == Color.RED
False
- >>> Color.blue != Color.red
+ >>> Color.BLUE != Color.RED
True
- >>> Color.blue == Color.blue
+ >>> 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
+ >>> Color.BLUE == 2
False
@@ -350,8 +350,8 @@ 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
+ ... FUNKY = 1
+ ... HAPPY = 3
...
... def describe(self):
... # self is the member here
@@ -363,16 +363,16 @@ usual. If we have this enumeration::
... @classmethod
... def favorite_mood(cls):
... # cls here is the enumeration
- ... return cls.happy
+ ... return cls.HAPPY
...
Then::
>>> Mood.favorite_mood()
- <Mood.happy: 3>
- >>> Mood.happy.describe()
- ('happy', 3)
- >>> str(Mood.funky)
+ <Mood.HAPPY: 3>
+ >>> Mood.HAPPY.describe()
+ ('HAPPY', 3)
+ >>> str(Mood.FUNKY)
'my custom str! 1'
The rules for what is allowed are as follows: names that start and end with
@@ -393,7 +393,7 @@ Subclassing an enumeration is allowed only if the enumeration does not define
any members. So this is forbidden::
>>> class MoreColor(Color):
- ... pink = 17
+ ... PINK = 17
...
Traceback (most recent call last):
...
@@ -406,8 +406,8 @@ But this is allowed::
... pass
...
>>> class Bar(Foo):
- ... happy = 1
- ... sad = 2
+ ... HAPPY = 1
+ ... SAD = 2
...
Allowing subclassing of enums that define members would lead to a violation of
@@ -423,7 +423,7 @@ Enumerations can be pickled and unpickled::
>>> from test.test_enum import Fruit
>>> from pickle import dumps, loads
- >>> Fruit.tomato is loads(dumps(Fruit.tomato))
+ >>> Fruit.TOMATO is loads(dumps(Fruit.TOMATO))
True
The usual restrictions for pickling apply: picklable enums must be defined in
@@ -444,15 +444,15 @@ Functional API
The :class:`Enum` class is callable, providing the following functional API::
- >>> Animal = Enum('Animal', 'ant bee cat dog')
+ >>> Animal = Enum('Animal', 'ANT BEE CAT DOG')
>>> Animal
<enum 'Animal'>
- >>> Animal.ant
- <Animal.ant: 1>
- >>> Animal.ant.value
+ >>> Animal.ANT
+ <Animal.ANT: 1>
+ >>> Animal.ANT.value
1
>>> list(Animal)
- [<Animal.ant: 1>, <Animal.bee: 2>, <Animal.cat: 3>, <Animal.dog: 4>]
+ [<Animal.ANT: 1>, <Animal.BEE: 2>, <Animal.CAT: 3>, <Animal.DOG: 4>]
The semantics of this API resemble :class:`~collections.namedtuple`. The first
argument of the call to :class:`Enum` is the name of the enumeration.
@@ -467,10 +467,10 @@ new class derived from :class:`Enum` is returned. In other words, the above
assignment to :class:`Animal` is equivalent to::
>>> class Animal(Enum):
- ... ant = 1
- ... bee = 2
- ... cat = 3
- ... dog = 4
+ ... ANT = 1
+ ... BEE = 2
+ ... CAT = 3
+ ... DOG = 4
...
The reason for defaulting to ``1`` as the starting number and not ``0`` is
@@ -483,7 +483,7 @@ 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::
- >>> Animal = Enum('Animal', 'ant bee cat dog', module=__name__)
+ >>> Animal = Enum('Animal', 'ANT BEE CAT DOG', module=__name__)
.. warning::
@@ -496,7 +496,7 @@ The new pickle protocol 4 also, in some circumstances, relies on
to find the class. For example, if the class was made available in class
SomeData in the global scope::
- >>> Animal = Enum('Animal', 'ant bee cat dog', qualname='SomeData.Animal')
+ >>> Animal = Enum('Animal', 'ANT BEE CAT DOG', qualname='SomeData.Animal')
The complete signature is::
@@ -507,19 +507,19 @@ The complete signature is::
:names: The Enum members. This can be a whitespace or comma separated string
(values will start at 1 unless otherwise specified)::
- 'red green blue' | 'red,green,blue' | 'red, green, blue'
+ 'RED GREEN BLUE' | 'RED,GREEN,BLUE' | 'RED, GREEN, BLUE'
or an iterator of names::
- ['red', 'green', 'blue']
+ ['RED', 'GREEN', 'BLUE']
or an iterator of (name, value) pairs::
- [('cyan', 4), ('magenta', 5), ('yellow', 6)]
+ [('CYAN', 4), ('MAGENTA', 5), ('YELLOW', 6)]
or a mapping::
- {'chartreuse': 7, 'sea_green': 11, 'rosemary': 42}
+ {'CHARTREUSE': 7, 'SEA_GREEN': 11, 'ROSEMARY': 42}
:module: name of module where new Enum class can be found.
@@ -546,40 +546,40 @@ to each other::
>>> from enum import IntEnum
>>> class Shape(IntEnum):
- ... circle = 1
- ... square = 2
+ ... CIRCLE = 1
+ ... SQUARE = 2
...
>>> class Request(IntEnum):
- ... post = 1
- ... get = 2
+ ... POST = 1
+ ... GET = 2
...
>>> Shape == 1
False
- >>> Shape.circle == 1
+ >>> Shape.CIRCLE == 1
True
- >>> Shape.circle == Request.post
+ >>> Shape.CIRCLE == Request.POST
True
However, they still can't be compared to standard :class:`Enum` enumerations::
>>> class Shape(IntEnum):
- ... circle = 1
- ... square = 2
+ ... CIRCLE = 1
+ ... SQUARE = 2
...
>>> class Color(Enum):
- ... red = 1
- ... green = 2
+ ... RED = 1
+ ... GREEN = 2
...
- >>> Shape.circle == Color.red
+ >>> Shape.CIRCLE == Color.RED
False
:class:`IntEnum` values behave like integers in other ways you'd expect::
- >>> int(Shape.circle)
+ >>> int(Shape.CIRCLE)
1
- >>> ['a', 'b', 'c'][Shape.circle]
+ >>> ['a', 'b', 'c'][Shape.CIRCLE]
'b'
- >>> [i for i in range(Shape.square)]
+ >>> [i for i in range(Shape.SQUARE)]
[0, 1]
@@ -656,39 +656,39 @@ flags being set, the boolean evaluation is :data:`False`::
>>> from enum import Flag
>>> class Color(Flag):
- ... red = auto()
- ... blue = auto()
- ... green = auto()
+ ... RED = auto()
+ ... BLUE = auto()
+ ... GREEN = auto()
...
- >>> Color.red & Color.green
+ >>> Color.RED & Color.GREEN
<Color.0: 0>
- >>> bool(Color.red & Color.green)
+ >>> bool(Color.RED & Color.GREEN)
False
Individual flags should have values that are powers of two (1, 2, 4, 8, ...),
while combinations of flags won't::
>>> class Color(Flag):
- ... red = auto()
- ... blue = auto()
- ... green = auto()
- ... white = red | blue | green
+ ... RED = auto()
+ ... BLUE = auto()
+ ... GREEN = auto()
+ ... WHITE = RED | BLUE | GREEN
...
- >>> Color.white
- <Color.white: 7>
+ >>> Color.WHITE
+ <Color.WHITE: 7>
Giving a name to the "no flags set" condition does not change its boolean
value::
>>> class Color(Flag):
- ... black = 0
- ... red = auto()
- ... blue = auto()
- ... green = auto()
+ ... BLACK = 0
+ ... RED = auto()
+ ... BLUE = auto()
+ ... GREEN = auto()
...
- >>> Color.black
- <Color.black: 0>
- >>> bool(Color.black)
+ >>> Color.BLACK
+ <Color.BLACK: 0>
+ >>> bool(Color.BLACK)
False
.. note::
@@ -776,12 +776,12 @@ Using :class:`auto`
Using :class:`object` would look like::
>>> class Color(NoValue):
- ... red = auto()
- ... blue = auto()
- ... green = auto()
+ ... RED = auto()
+ ... BLUE = auto()
+ ... GREEN = auto()
...
- >>> Color.green
- <Color.green>
+ >>> Color.GREEN
+ <Color.GREEN>
Using :class:`object`
@@ -790,12 +790,12 @@ Using :class:`object`
Using :class:`object` would look like::
>>> class Color(NoValue):
- ... red = object()
- ... green = object()
- ... blue = object()
+ ... RED = object()
+ ... GREEN = object()
+ ... BLUE = object()
...
- >>> Color.green
- <Color.green>
+ >>> Color.GREEN
+ <Color.GREEN>
Using a descriptive string
@@ -804,13 +804,13 @@ Using a descriptive string
Using a string as the value would look like::
>>> class Color(NoValue):
- ... red = 'stop'
- ... green = 'go'
- ... blue = 'too fast!'
+ ... RED = 'stop'
+ ... GREEN = 'go'
+ ... BLUE = 'too fast!'
...
- >>> Color.green
- <Color.green>
- >>> Color.green.value
+ >>> Color.GREEN
+ <Color.GREEN>
+ >>> Color.GREEN.value
'go'
@@ -827,13 +827,13 @@ Using an auto-numbering :meth:`__new__` would look like::
... return obj
...
>>> class Color(AutoNumber):
- ... red = ()
- ... green = ()
- ... blue = ()
+ ... RED = ()
+ ... GREEN = ()
+ ... BLUE = ()
...
- >>> Color.green
- <Color.green>
- >>> Color.green.value
+ >>> Color.GREEN
+ <Color.GREEN>
+ >>> Color.GREEN.value
2
@@ -897,14 +897,14 @@ alias::
... % (a, e))
...
>>> class Color(DuplicateFreeEnum):
- ... red = 1
- ... green = 2
- ... blue = 3
- ... grene = 2
+ ... RED = 1
+ ... GREEN = 2
+ ... BLUE = 3
+ ... GRENE = 2
...
Traceback (most recent call last):
...
- ValueError: aliases not allowed in DuplicateFreeEnum: 'grene' --> 'green'
+ ValueError: aliases not allowed in DuplicateFreeEnum: 'GRENE' --> 'GREEN'
.. note::
@@ -1007,10 +1007,10 @@ be provided. It will be checked against the actual order of the enumeration
and raise an error if the two do not match::
>>> class Color(Enum):
- ... _order_ = 'red green blue'
- ... red = 1
- ... blue = 3
- ... green = 2
+ ... _order_ = 'RED GREEN BLUE'
+ ... RED = 1
+ ... BLUE = 3
+ ... GREEN = 2
...
Traceback (most recent call last):
...
@@ -1028,7 +1028,8 @@ and raise an error if the two do not match::
normally accessed as ``EnumClass.member``. Under certain circumstances they
can also be accessed as ``EnumClass.member.member``, but you should never do
this as that lookup may fail or, worse, return something besides the
-:class:`Enum` member you are looking for::
+:class:`Enum` member you are looking for (this is another good reason to use
+all-uppercase names for members)::
>>> class FieldTypes(Enum):
... name = 0
@@ -1078,15 +1079,15 @@ If a combination of Flag members is not named, the :func:`repr` will include
all named flags and all named combinations of flags that are in the value::
>>> class Color(Flag):
- ... red = auto()
- ... green = auto()
- ... blue = auto()
- ... magenta = red | blue
- ... yellow = red | green
- ... cyan = green | blue
+ ... RED = auto()
+ ... GREEN = auto()
+ ... BLUE = auto()
+ ... MAGENTA = RED | BLUE
+ ... YELLOW = RED | GREEN
+ ... CYAN = GREEN | BLUE
...
>>> Color(3) # named combination
- <Color.yellow: 3>
+ <Color.YELLOW: 3>
>>> Color(7) # not named combination
- <Color.cyan|magenta|blue|yellow|green|red: 7>
+ <Color.CYAN|MAGENTA|BLUE|YELLOW|GREEN|RED: 7>