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<!DOCTYPE html>

<head>

<title>Enum HOWTO — مستندات Python3.14.6</title><meta name="viewport" content="width=device-width, initial-scale=1.0">

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<h3><a href="../contents.html">فهرست عناوین</a></h3>

<ul>

<li><a class="reference internal" href="#">Enum HOWTO</a><ul>

<li><a class="reference internal" href="#programmatic-access-to-enumeration-members-and-their-attributes">Programmatic access to enumeration members and their attributes</a></li>

<li><a class="reference internal" href="#duplicating-enum-members-and-values">Duplicating enum members and values</a></li>

<li><a class="reference internal" href="#ensuring-unique-enumeration-values">Ensuring unique enumeration values</a></li>

<li><a class="reference internal" href="#using-automatic-values">Using automatic values</a></li>

<li><a class="reference internal" href="#iteration">Iteration</a></li>

<li><a class="reference internal" href="#comparisons">Comparisons</a></li>

<li><a class="reference internal" href="#allowed-members-and-attributes-of-enumerations">Allowed members and attributes of enumerations</a></li>

<li><a class="reference internal" href="#restricted-enum-subclassing">Restricted Enum subclassing</a></li>

<li><a class="reference internal" href="#dataclass-support">Dataclass support</a></li>

<li><a class="reference internal" href="#pickling">Pickling</a></li>

<li><a class="reference internal" href="#functional-api">Functional API</a></li>

<li><a class="reference internal" href="#derived-enumerations">Derived Enumerations</a><ul>

<li><a class="reference internal" href="#intenum">IntEnum</a></li>

<li><a class="reference internal" href="#strenum">StrEnum</a></li>

<li><a class="reference internal" href="#intflag">IntFlag</a></li>

<li><a class="reference internal" href="#others">Others</a></li>

</ul>

</li>

<li><a class="reference internal" href="#finer-points">Finer Points</a><ul>

<li><a class="reference internal" href="#supported-dunder-and-sunder-names">Supported <code class="docutils literal notranslate">__dunder__</code> and <code class="docutils literal notranslate">_sunder_</code> names</a></li>

<li><a class="reference internal" href="#private-names">_Private__names</a></li>

<li><a class="reference internal" href="#enum-member-type"><code class="docutils literal notranslate">Enum</code> member type</a></li>

<li><a class="reference internal" href="#creating-members-that-are-mixed-with-other-data-types">Creating members that are mixed with other data types</a></li>

<li><a class="reference internal" href="#boolean-value-of-enum-classes-and-members">Boolean value of <code class="docutils literal notranslate">Enum</code> classes and members</a></li>

<li><a class="reference internal" href="#enum-classes-with-methods"><code class="docutils literal notranslate">Enum</code> classes with methods</a></li>

<li><a class="reference internal" href="#combining-members-of-flag">Combining members of <code class="docutils literal notranslate">Flag</code></a></li>

<li><a class="reference internal" href="#flag-and-intflag-minutia"><code class="docutils literal notranslate">Flag</code> and <code class="docutils literal notranslate">IntFlag</code> minutia</a></li>

</ul>

</li>

<li><a class="reference internal" href="#how-are-enums-and-flags-different">How are Enums and Flags different?</a><ul>

<li><a class="reference internal" href="#enum-classes">Enum Classes</a></li>

<li><a class="reference internal" href="#flag-classes">Flag Classes</a></li>

<li><a class="reference internal" href="#enum-members-aka-instances">Enum Members (aka instances)</a></li>

<li><a class="reference internal" href="#flag-members">Flag Members</a></li>

</ul>

</li>

<li><a class="reference internal" href="#enum-cookbook">Enum Cookbook</a><ul>

<li><a class="reference internal" href="#omitting-values">Omitting values</a><ul>

<li><a class="reference internal" href="#using-auto">Using <code class="xref py py-class docutils literal notranslate">auto</code></a></li>

<li><a class="reference internal" href="#using-object">Using <code class="xref py py-class docutils literal notranslate">object</code></a></li>

<li><a class="reference internal" href="#using-a-descriptive-string">Using a descriptive string</a></li>

<li><a class="reference internal" href="#using-a-custom-new">Using a custom <code class="xref py py-meth docutils literal notranslate">__new__()</code></a></li>

</ul>

</li>

<li><a class="reference internal" href="#orderedenum">OrderedEnum</a></li>

<li><a class="reference internal" href="#duplicatefreeenum">DuplicateFreeEnum</a></li>

<li><a class="reference internal" href="#multivalueenum">MultiValueEnum</a></li>

<li><a class="reference internal" href="#planet">Planet</a></li>

<li><a class="reference internal" href="#timeperiod">TimePeriod</a></li>

</ul>

</li>

<li><a class="reference internal" href="#subclassing-enumtype">Subclassing EnumType</a></li>

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<h1>Enum HOWTO<a class="headerlink" href="#enum-howto" title="Link to this heading">¶</a></h1>

An <a class="reference internal" href="../library/enum.html#enum.Enum" title="enum.Enum"><code class="xref py py-class docutils literal notranslate">Enum</code></a> is a set of symbolic names bound to unique values. They are

similar to global variables, but they offer a more useful <a class="reference internal" href="../library/functions.html#repr" title="repr"><code class="xref py py-func docutils literal notranslate">repr()</code></a>,

grouping, type-safety, and a few other features.

They are most useful when you have a variable that can take one of a limited

selection of values. For example, the days of the week:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> from enum import Enum

>>> class Weekday(Enum):

... MONDAY = 1

... TUESDAY = 2

... WEDNESDAY = 3

... THURSDAY = 4

... FRIDAY = 5

... SATURDAY = 6

... SUNDAY = 7

</pre></div>

</div>

Or perhaps the RGB primary colors:

>>> class Color(Enum):

... RED = 1

... GREEN = 2

... BLUE = 3

</pre></div>

</div>

As you can see, creating an <a class="reference internal" href="../library/enum.html#enum.Enum" title="enum.Enum"><code class="xref py py-class docutils literal notranslate">Enum</code></a> is as simple as writing a class that

inherits from <code class="xref py py-class docutils literal notranslate">Enum</code> itself.

توجه

Case of Enum Members

Because Enums are used to represent constants, and to help avoid issues

with name clashes between mixin-class methods/attributes and enum names,

we strongly recommend using UPPER_CASE names for members, and will be using

that style in our examples.

</div>

Depending on the nature of the enum a member's value may or may not be

important, but either way that value can be used to get the corresponding

member:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> Weekday(3)

<Weekday.WEDNESDAY: 3>

</pre></div>

</div>

As you can see, the <code class="docutils literal notranslate">repr()</code> of a member shows the enum name, the member name,

and the value. The <code class="docutils literal notranslate">str()</code> of a member shows only the enum name and member

name:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> print(Weekday.THURSDAY)

Weekday.THURSDAY

</pre></div>

</div>

The type of an enumeration member is the enum it belongs to:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> type(Weekday.MONDAY)

>>> isinstance(Weekday.FRIDAY, Weekday)

True

</pre></div>

</div>

Enum members have an attribute that contains just their <code class="xref py py-attr docutils literal notranslate">name</code>:

TUESDAY

</pre></div>

</div>

Likewise, they have an attribute for their <code class="xref py py-attr docutils literal notranslate">value</code>:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> Weekday.WEDNESDAY.value

3

</pre></div>

</div>

Unlike many languages that treat enumerations solely as name/value pairs,

Python Enums can have behavior added. For example, <a class="reference internal" href="../library/datetime.html#datetime.date" title="datetime.date"><code class="xref py py-class docutils literal notranslate">datetime.date</code></a>

has two methods for returning the weekday:

<a class="reference internal" href="../library/datetime.html#datetime.date.weekday" title="datetime.date.weekday"><code class="xref py py-meth docutils literal notranslate">weekday()</code></a> and <a class="reference internal" href="../library/datetime.html#datetime.date.isoweekday" title="datetime.date.isoweekday"><code class="xref py py-meth docutils literal notranslate">isoweekday()</code></a>.

The difference is that one of them counts from 0-6 and the other from 1-7.

Rather than keep track of that ourselves we can add a method to the <code class="xref py py-class docutils literal notranslate">Weekday</code>

enum to extract the day from the <code class="xref py py-class docutils literal notranslate">date</code> instance and return the matching

enum member:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>@classmethod

def from_date(cls, date):

return cls(date.isoweekday())

</pre></div>

</div>

The complete <code class="xref py py-class docutils literal notranslate">Weekday</code> enum now looks like this:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> class Weekday(Enum):

... MONDAY = 1

... TUESDAY = 2

... WEDNESDAY = 3

... THURSDAY = 4

... FRIDAY = 5

... SATURDAY = 6

... SUNDAY = 7

... #

... @classmethod

... def from_date(cls, date):

... return cls(date.isoweekday())

</pre></div>

</div>

Now we can find out what today is! Observe:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> import datetime as dt

>>> Weekday.from_date(dt.date.today())

<Weekday.TUESDAY: 2>

</pre></div>

</div>

Of course, if you're reading this on some other day, you'll see that day instead.

This <code class="xref py py-class docutils literal notranslate">Weekday</code> enum is great if our variable only needs one day, but

what if we need several? Maybe we're writing a function to plot chores during

a week, and don't want to use a <a class="reference internal" href="../library/stdtypes.html#list" title="list"><code class="xref py py-class docutils literal notranslate">list</code></a> -- we could use a different type

of <a class="reference internal" href="../library/enum.html#enum.Enum" title="enum.Enum"><code class="xref py py-class docutils literal notranslate">Enum</code></a>:

>>> class Weekday(Flag):

... MONDAY = 1

... TUESDAY = 2

... WEDNESDAY = 4

... THURSDAY = 8

... FRIDAY = 16

... SATURDAY = 32

... SUNDAY = 64

</pre></div>

</div>

We've changed two things: we're inherited from <a class="reference internal" href="../library/enum.html#enum.Flag" title="enum.Flag"><code class="xref py py-class docutils literal notranslate">Flag</code></a>, and the values are

all powers of 2.

Just like the original <code class="xref py py-class docutils literal notranslate">Weekday</code> enum above, we can have a single selection:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> first_week_day = Weekday.MONDAY

>>> first_week_day

<Weekday.MONDAY: 1>

</pre></div>

</div>

But <a class="reference internal" href="../library/enum.html#enum.Flag" title="enum.Flag"><code class="xref py py-class docutils literal notranslate">Flag</code></a> also allows us to combine several members into a single

variable:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> weekend = Weekday.SATURDAY | Weekday.SUNDAY

>>> weekend

<Weekday.SATURDAY|SUNDAY: 96>

</pre></div>

</div>

You can even iterate over a <a class="reference internal" href="../library/enum.html#enum.Flag" title="enum.Flag"><code class="xref py py-class docutils literal notranslate">Flag</code></a> variable:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> for day in weekend:

... print(day)

Weekday.SATURDAY

Weekday.SUNDAY

</pre></div>

</div>

Okay, let's get some chores set up:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> chores_for_ethan = {

... 'feed the cat': Weekday.MONDAY | Weekday.WEDNESDAY | Weekday.FRIDAY,

... 'do the dishes': Weekday.TUESDAY | Weekday.THURSDAY,

... 'answer SO questions': Weekday.SATURDAY,

... }

</pre></div>

</div>

And a function to display the chores for a given day:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> def show_chores(chores, day):

... for chore, days in chores.items():

... if day in days:

... print(chore)

...

>>> show_chores(chores_for_ethan, Weekday.SATURDAY)

answer SO questions

</pre></div>

</div>

In cases where the actual values of the members do not matter, you can save

yourself some work and use <a class="reference internal" href="../library/enum.html#enum.auto" title="enum.auto"><code class="xref py py-func docutils literal notranslate">auto()</code></a> for the values:

>>> class Weekday(Flag):

... MONDAY = auto()

... TUESDAY = auto()

... WEDNESDAY = auto()

... THURSDAY = auto()

... FRIDAY = auto()

... SATURDAY = auto()

... SUNDAY = auto()

... WEEKEND = SATURDAY | SUNDAY

</pre></div>

</div>

<h2>Programmatic access to enumeration members and their attributes<a class="headerlink" href="#programmatic-access-to-enumeration-members-and-their-attributes" title="Link to this heading">¶</a></h2>

Sometimes it's useful to access members in enumerations programmatically (i.e.

situations where <code class="docutils literal notranslate">Color.RED</code> won't do because the exact color is not known

at program-writing time). <code class="docutils literal notranslate">Enum</code> allows such access:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> Color(1)

<Color.RED: 1>

>>> Color(3)

<Color.BLUE: 3>

</pre></div>

</div>

If you want to access enum members by name, use item access:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> Color['RED']

<Color.RED: 1>

>>> Color['GREEN']

<Color.GREEN: 2>

</pre></div>

</div>

If you have an enum member and need its <code class="xref py py-attr docutils literal notranslate">name</code> or <code class="xref py py-attr docutils literal notranslate">value</code>:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> member = Color.RED

>>> member.name

'RED'

>>> member.value

1

</pre></div>

</div>

</section>

<h2>Duplicating enum members and values<a class="headerlink" href="#duplicating-enum-members-and-values" title="Link to this heading">¶</a></h2>

Having two enum members with the same name is invalid:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> class Shape(Enum):

... SQUARE = 2

... SQUARE = 3

...

Traceback (most recent call last):

...

TypeError: 'SQUARE' already defined as 2

</pre></div>

</div>

However, an enum member can have other names associated with it. Given two

entries <code class="docutils literal notranslate">A</code> and <code class="docutils literal notranslate">B</code> with the same value (and <code class="docutils literal notranslate">A</code> defined first), <code class="docutils literal notranslate">B</code>

is an alias for the member <code class="docutils literal notranslate">A</code>. By-value lookup of the value of <code class="docutils literal notranslate">A</code> will

return the member <code class="docutils literal notranslate">A</code>. By-name lookup of <code class="docutils literal notranslate">A</code> will return the member <code class="docutils literal notranslate">A</code>.

By-name lookup of <code class="docutils literal notranslate">B</code> will also return the member <code class="docutils literal notranslate">A</code>:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> class Shape(Enum):

... SQUARE = 2

... DIAMOND = 1

... CIRCLE = 3

... ALIAS_FOR_SQUARE = 2

...

>>> Shape.SQUARE

<Shape.SQUARE: 2>

>>> Shape.ALIAS_FOR_SQUARE

<Shape.SQUARE: 2>

>>> Shape(2)

<Shape.SQUARE: 2>

</pre></div>

</div>

توجه

Attempting to create a member with the same name as an already

defined attribute (another member, a method, etc.) or attempting to create

an attribute with the same name as a member is not allowed.

</div>

</section>

<h2>Ensuring unique enumeration values<a class="headerlink" href="#ensuring-unique-enumeration-values" title="Link to this heading">¶</a></h2>

By default, enumerations allow multiple names as aliases for the same value.

When this behavior isn't desired, you can use the <a class="reference internal" href="../library/enum.html#enum.unique" title="enum.unique"><code class="xref py py-func docutils literal notranslate">unique()</code></a> decorator:

>>> @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

</pre></div>

</div>

</section>

<h2>Using automatic values<a class="headerlink" href="#using-automatic-values" title="Link to this heading">¶</a></h2>

If the exact value is unimportant you can use <a class="reference internal" href="../library/enum.html#enum.auto" title="enum.auto"><code class="xref py py-class docutils literal notranslate">auto</code></a>:

>>> class Color(Enum):

... RED = auto()

... BLUE = auto()

... GREEN = auto()

...

>>> [member.value for member in Color]

[1, 2, 3]

</pre></div>

</div>

The values are chosen by <a class="reference internal" href="../library/enum.html#enum.Enum._generate_next_value_" title="enum.Enum._generate_next_value_"><code class="xref py py-func docutils literal notranslate">_generate_next_value_()</code></a>, which can be

overridden:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> class AutoName(Enum):

... @staticmethod

... def _generate_next_value_(name, start, count, last_values):

... return name

...

>>> class Ordinal(AutoName):

... NORTH = auto()

... SOUTH = auto()

... EAST = auto()

... WEST = auto()

...

['NORTH', 'SOUTH', 'EAST', 'WEST']

</pre></div>

</div>

توجه

The <a class="reference internal" href="../library/enum.html#enum.Enum._generate_next_value_" title="enum.Enum._generate_next_value_"><code class="xref py py-meth docutils literal notranslate">_generate_next_value_()</code></a> method must be defined before any members.

</div>

</section>

<h2>Iteration<a class="headerlink" href="#iteration" title="Link to this heading">¶</a></h2>

Iterating over the members of an enum does not provide the aliases:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> list(Shape)

[<Shape.SQUARE: 2>, <Shape.DIAMOND: 1>, <Shape.CIRCLE: 3>]

>>> list(Weekday)

[<Weekday.MONDAY: 1>, <Weekday.TUESDAY: 2>, <Weekday.WEDNESDAY: 4>, <Weekday.THURSDAY: 8>, <Weekday.FRIDAY: 16>, <Weekday.SATURDAY: 32>, <Weekday.SUNDAY: 64>]

</pre></div>

</div>

Note that the aliases <code class="docutils literal notranslate">Shape.ALIAS_FOR_SQUARE</code> and <code class="docutils literal notranslate">Weekday.WEEKEND</code> aren't shown.

The special attribute <code class="docutils literal notranslate">__members__</code> is a read-only ordered mapping of names

to members. It includes all names defined in the enumeration, including the

aliases:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> 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>)

</pre></div>

</div>

The <code class="docutils literal notranslate">__members__</code> attribute can be used for detailed programmatic access to

the enumeration members. For example, finding all the aliases:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> [name for name, member in Shape.__members__.items() if member.name != name]

['ALIAS_FOR_SQUARE']

</pre></div>

</div>

توجه

Aliases for flags include values with multiple flags set, such as <code class="docutils literal notranslate">3</code>,

and no flags set, i.e. <code class="docutils literal notranslate">0</code>.

</div>

</section>

<h2>Comparisons<a class="headerlink" href="#comparisons" title="Link to this heading">¶</a></h2>

Enumeration members are compared by identity:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> Color.RED is Color.RED

True

>>> Color.RED is Color.BLUE

False

>>> Color.RED is not Color.BLUE

True

</pre></div>

</div>

Ordered comparisons between enumeration values are not supported. Enum

members are not integers (but see <a class="reference internal" href="#intenum">IntEnum</a> below):

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> Color.RED < Color.BLUE

Traceback (most recent call last):

File "<stdin>", line 1, in <module>

TypeError: '<' not supported between instances of 'Color' and 'Color'

</pre></div>

</div>

Equality comparisons are defined though:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> Color.BLUE == Color.RED

False

>>> Color.BLUE != Color.RED

True

>>> Color.BLUE == Color.BLUE

True

</pre></div>

</div>

Comparisons against non-enumeration values will always compare not equal

(again, <a class="reference internal" href="../library/enum.html#enum.IntEnum" title="enum.IntEnum"><code class="xref py py-class docutils literal notranslate">IntEnum</code></a> was explicitly designed to behave differently, see

below):

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> Color.BLUE == 2

False

</pre></div>

</div>

هشدار

It is possible to reload modules -- if a reloaded module contains

enums, they will be recreated, and the new members may not

compare identical/equal to the original members.

</div>

</section>

<h2>Allowed members and attributes of enumerations<a class="headerlink" href="#allowed-members-and-attributes-of-enumerations" title="Link to this heading">¶</a></h2>

Most of the examples above use integers for enumeration values. Using integers

is short and handy (and provided by default by the <a class="reference internal" href="#functional-api">Functional API</a>), but not

strictly enforced. In the vast majority of use-cases, one doesn't care what

the actual value of an enumeration is. But if the value is important,

enumerations can have arbitrary values.

Enumerations are Python classes, and can have methods and special methods as

usual. If we have this enumeration:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> class Mood(Enum):

... FUNKY = 1

... HAPPY = 3

...

... def describe(self):

... # self is the member here

... return self.name, self.value

...

... def __str__(self):

... return 'my custom str! {0}'.format(self.value)

...

... @classmethod

... def favorite_mood(cls):

... # cls here is the enumeration

... return cls.HAPPY

...

</pre></div>

</div>

Then:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> Mood.favorite_mood()

<Mood.HAPPY: 3>

>>> Mood.HAPPY.describe()

('HAPPY', 3)

>>> str(Mood.FUNKY)

'my custom str! 1'

</pre></div>

</div>

The rules for what is allowed are as follows: names that start and end with

a single underscore are reserved by enum and cannot be used; all other

attributes defined within an enumeration will become members of this

enumeration, with the exception of special methods (<a class="reference internal" href="../reference/datamodel.html#object.__str__" title="object.__str__"><code class="xref py py-meth docutils literal notranslate">__str__()</code></a>,

<a class="reference internal" href="../reference/datamodel.html#object.__add__" title="object.__add__"><code class="xref py py-meth docutils literal notranslate">__add__()</code></a>, etc.), descriptors (methods are also descriptors), and

variable names listed in <a class="reference internal" href="../library/enum.html#enum.Enum._ignore_" title="enum.Enum._ignore_"><code class="xref py py-attr docutils literal notranslate">_ignore_</code></a>.

Note: if your enumeration defines <a class="reference internal" href="../reference/datamodel.html#object.__new__" title="object.__new__"><code class="xref py py-meth docutils literal notranslate">__new__()</code></a> and/or <a class="reference internal" href="../reference/datamodel.html#object.__init__" title="object.__init__"><code class="xref py py-meth docutils literal notranslate">__init__()</code></a>,

any value(s) given to the enum member will be passed into those methods.

See <a class="reference internal" href="#planet">Planet</a> for an example.

توجه

The <a class="reference internal" href="../reference/datamodel.html#object.__new__" title="object.__new__"><code class="xref py py-meth docutils literal notranslate">__new__()</code></a> method, if defined, is used during creation of the Enum

members; it is then replaced by Enum's <code class="xref py py-meth docutils literal notranslate">__new__()</code> which is used after

class creation for lookup of existing members. See <a class="reference internal" href="#new-vs-init">When to use __new__() vs. __init__()</a> for

more details.

</div>

</section>

<h2>Restricted Enum subclassing<a class="headerlink" href="#restricted-enum-subclassing" title="Link to this heading">¶</a></h2>

A new <a class="reference internal" href="../library/enum.html#enum.Enum" title="enum.Enum"><code class="xref py py-class docutils literal notranslate">Enum</code></a> class must have one base enum class, up to one concrete

data type, and as many <a class="reference internal" href="../library/functions.html#object" title="object"><code class="xref py py-class docutils literal notranslate">object</code></a>-based mixin classes as needed. The

order of these base classes is:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>class EnumName([mix-in, ...,] [data-type,] base-enum):

pass

</pre></div>

</div>

Also, subclassing an enumeration is allowed only if the enumeration does not define

any members. So this is forbidden:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> class MoreColor(Color):

... PINK = 17

...

Traceback (most recent call last):

...

TypeError: <enum 'MoreColor'> cannot extend <enum 'Color'>

</pre></div>

</div>

But this is allowed:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> class Foo(Enum):

... def some_behavior(self):

... pass

...

>>> class Bar(Foo):

... HAPPY = 1

... SAD = 2

...

</pre></div>

</div>

Allowing subclassing of enums that define members would lead to a violation of

some important invariants of types and instances. On the other hand, it makes

sense to allow sharing some common behavior between a group of enumerations.

(See <a class="reference internal" href="#orderedenum">OrderedEnum</a> for an example.)

</section>

<h2>Dataclass support<a class="headerlink" href="#dataclass-support" title="Link to this heading">¶</a></h2>

When inheriting from a <a class="reference internal" href="../library/dataclasses.html#dataclasses.dataclass" title="dataclasses.dataclass"><code class="xref py py-class docutils literal notranslate">dataclass</code></a>,

the <a class="reference internal" href="../library/enum.html#enum.Enum.__repr__" title="enum.Enum.__repr__"><code class="xref py py-meth docutils literal notranslate">__repr__()</code></a> omits the inherited class' name. For example:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> from dataclasses import dataclass, field

>>> @dataclass

... class CreatureDataMixin:

... size: str

... legs: int

... tail: bool = field(repr=False, default=True)

...

>>> class Creature(CreatureDataMixin, Enum):

... BEETLE = 'small', 6

... DOG = 'medium', 4

...

>>> Creature.DOG

<Creature.DOG: size='medium', legs=4>

</pre></div>

</div>

Use the <a class="reference internal" href="../library/dataclasses.html#dataclasses.dataclass" title="dataclasses.dataclass"><code class="xref py py-func docutils literal notranslate">dataclass()</code></a> argument <code class="docutils literal notranslate">repr=False</code>

to use the standard <a class="reference internal" href="../library/functions.html#repr" title="repr"><code class="xref py py-func docutils literal notranslate">repr()</code></a>.

تغییر داده شده در نسخه 3.12: Only the dataclass fields are shown in the value area, not the dataclass'

name.

</div>

توجه

Adding <a class="reference internal" href="../library/dataclasses.html#dataclasses.dataclass" title="dataclasses.dataclass"><code class="xref py py-func docutils literal notranslate">dataclass()</code></a> decorator to <a class="reference internal" href="../library/enum.html#enum.Enum" title="enum.Enum"><code class="xref py py-class docutils literal notranslate">Enum</code></a>

and its subclasses is not supported. It will not raise any errors,

but it will produce very strange results at runtime, such as members

being equal to each other:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> @dataclass # don't do this: it does not make any sense

... class Color(Enum):

... RED = 1

... BLUE = 2

...

False

>>> Color.RED == Color.BLUE # problem is here: they should not be equal

True

</pre></div>

</div>

</section>

<h2>Pickling<a class="headerlink" href="#pickling" title="Link to this heading">¶</a></h2>

Enumerations can be pickled and unpickled:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> from test.test_enum import Fruit

>>> from pickle import dumps, loads

>>> Fruit.TOMATO is loads(dumps(Fruit.TOMATO))

True

</pre></div>

</div>

The usual restrictions for pickling apply: picklable enums must be defined in

the top level of a module, since unpickling requires them to be importable

from that module.

توجه

With pickle protocol version 4 it is possible to easily pickle enums

nested in other classes.

</div>

It is possible to modify how enum members are pickled/unpickled by defining

<a class="reference internal" href="../library/pickle.html#object.__reduce_ex__" title="object.__reduce_ex__"><code class="xref py py-meth docutils literal notranslate">__reduce_ex__()</code></a> in the enumeration class. The default method is by-value,

but enums with complicated values may want to use by-name:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> import enum

>>> class MyEnum(enum.Enum):

... __reduce_ex__ = enum.pickle_by_enum_name

</pre></div>

</div>

توجه

Using by-name for flags is not recommended, as unnamed aliases will

not unpickle.

</div>

</section>

<h2>Functional API<a class="headerlink" href="#functional-api" title="Link to this heading">¶</a></h2>

The <a class="reference internal" href="../library/enum.html#enum.Enum" title="enum.Enum"><code class="xref py py-class docutils literal notranslate">Enum</code></a> class is callable, providing the following functional API:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> Animal = Enum('Animal', 'ANT BEE CAT DOG')

>>> Animal

>>> Animal.ANT

<Animal.ANT: 1>

>>> list(Animal)

[<Animal.ANT: 1>, <Animal.BEE: 2>, <Animal.CAT: 3>, <Animal.DOG: 4>]

</pre></div>

</div>

The semantics of this API resemble <a class="reference internal" href="../library/collections.html#collections.namedtuple" title="collections.namedtuple"><code class="xref py py-class docutils literal notranslate">namedtuple</code></a>. The first

argument of the call to <a class="reference internal" href="../library/enum.html#enum.Enum" title="enum.Enum"><code class="xref py py-class docutils literal notranslate">Enum</code></a> is the name of the enumeration.

The second argument is the source of enumeration member names. It can be a

whitespace-separated string of names, a sequence of names, a sequence of

2-tuples with key/value pairs, or a mapping (e.g. dictionary) of names to

values. The last two options enable assigning arbitrary values to

enumerations; the others auto-assign increasing integers starting with 1 (use

the <code class="docutils literal notranslate">start</code> parameter to specify a different starting value). A

new class derived from <a class="reference internal" href="../library/enum.html#enum.Enum" title="enum.Enum"><code class="xref py py-class docutils literal notranslate">Enum</code></a> is returned. In other words, the above

assignment to <code class="xref py py-class docutils literal notranslate">Animal</code> is equivalent to:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> class Animal(Enum):

... ANT = 1

... BEE = 2

... CAT = 3

... DOG = 4

...

</pre></div>

</div>

The reason for defaulting to <code class="docutils literal notranslate">1</code> as the starting number and not <code class="docutils literal notranslate">0</code> is

that <code class="docutils literal notranslate">0</code> is <code class="docutils literal notranslate">False</code> in a boolean sense, but by default enum members all

evaluate to <code class="docutils literal notranslate">True</code>.

Pickling enums created with the functional API can be tricky as frame stack

implementation details are used to try and figure out which module the

enumeration is being created in (e.g. it will fail if you use a utility

function in a separate module, and also may not work on IronPython or Jython).

The solution is to specify the module name explicitly as follows:

</pre></div>

</div>

هشدار

If <code class="docutils literal notranslate">module</code> is not supplied, and Enum cannot determine what it is,

the new Enum members will not be unpicklable; to keep errors closer to

the source, pickling will be disabled.

</div>

The new pickle protocol 4 also, in some circumstances, relies on

<a class="reference internal" href="../reference/datamodel.html#type.__qualname__" title="type.__qualname__"><code class="xref py py-attr docutils literal notranslate">__qualname__</code></a> being set to the location where pickle will be able

to find the class. For example, if the class was made available in class

SomeData in the global scope:

</pre></div>

</div>

The complete signature is:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>Enum(

value='NewEnumName',

names=<...>,

*,

module='...',

qualname='...',

type=<mixed-in class>,

start=1,

)

</pre></div>

</div>

<ul>

<li>value: What the new enum class will record as its name.</li>

<li>names: The enum members. This can be a whitespace- or comma-separated string

(values will start at 1 unless otherwise specified):

<div class="highlight-python3 notranslate"><div class="highlight"><pre>'RED GREEN BLUE' | 'RED,GREEN,BLUE' | 'RED, GREEN, BLUE'

</pre></div>

</div>

or an iterator of names:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>['RED', 'GREEN', 'BLUE']

</pre></div>

</div>

or an iterator of (name, value) pairs:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>[('CYAN', 4), ('MAGENTA', 5), ('YELLOW', 6)]

</pre></div>

</div>

or a mapping:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>{'CHARTREUSE': 7, 'SEA_GREEN': 11, 'ROSEMARY': 42}

</pre></div>

</div>

</li>

<li>module: name of module where new enum class can be found.</li>

<li>qualname: where in module new enum class can be found.</li>

<li>type: type to mix in to new enum class.</li>

<li>start: number to start counting at if only names are passed in.</li>

</ul>

تغییر داده شده در نسخه 3.5: The start parameter was added.

</div>

</section>

<h2>Derived Enumerations<a class="headerlink" href="#derived-enumerations" title="Link to this heading">¶</a></h2>

<h3>IntEnum<a class="headerlink" href="#intenum" title="Link to this heading">¶</a></h3>

The first variation of <a class="reference internal" href="../library/enum.html#enum.Enum" title="enum.Enum"><code class="xref py py-class docutils literal notranslate">Enum</code></a> that is provided is also a subclass of

<a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate">int</code></a>. Members of an <a class="reference internal" href="../library/enum.html#enum.IntEnum" title="enum.IntEnum"><code class="xref py py-class docutils literal notranslate">IntEnum</code></a> can be compared to integers;

by extension, integer enumerations of different types can also be compared

to each other:

>>> class Shape(IntEnum):

... CIRCLE = 1

... SQUARE = 2

...

>>> class Request(IntEnum):

... POST = 1

... GET = 2

...

>>> Shape == 1

False

>>> Shape.CIRCLE == 1

True

>>> Shape.CIRCLE == Request.POST

True

</pre></div>

</div>

However, they still can't be compared to standard <a class="reference internal" href="../library/enum.html#enum.Enum" title="enum.Enum"><code class="xref py py-class docutils literal notranslate">Enum</code></a> enumerations:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> class Shape(IntEnum):

... CIRCLE = 1

... SQUARE = 2

...

>>> class Color(Enum):

... RED = 1

... GREEN = 2

...

>>> Shape.CIRCLE == Color.RED

False

</pre></div>

</div>

<a class="reference internal" href="../library/enum.html#enum.IntEnum" title="enum.IntEnum"><code class="xref py py-class docutils literal notranslate">IntEnum</code></a> values behave like integers in other ways you'd expect:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> int(Shape.CIRCLE)

1

>>> ['a', 'b', 'c'][Shape.CIRCLE]

'b'

>>> [i for i in range(Shape.SQUARE)]

[0, 1]

</pre></div>

</div>

</section>

<h3>StrEnum<a class="headerlink" href="#strenum" title="Link to this heading">¶</a></h3>

The second variation of <a class="reference internal" href="../library/enum.html#enum.Enum" title="enum.Enum"><code class="xref py py-class docutils literal notranslate">Enum</code></a> that is provided is also a subclass of

<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate">str</code></a>. Members of a <a class="reference internal" href="../library/enum.html#enum.StrEnum" title="enum.StrEnum"><code class="xref py py-class docutils literal notranslate">StrEnum</code></a> can be compared to strings;

by extension, string enumerations of different types can also be compared

to each other.

Added in version 3.11.

</div>

</section>

<h3>IntFlag<a class="headerlink" href="#intflag" title="Link to this heading">¶</a></h3>

The next variation of <a class="reference internal" href="../library/enum.html#enum.Enum" title="enum.Enum"><code class="xref py py-class docutils literal notranslate">Enum</code></a> provided, <a class="reference internal" href="../library/enum.html#enum.IntFlag" title="enum.IntFlag"><code class="xref py py-class docutils literal notranslate">IntFlag</code></a>, is also based

on <a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate">int</code></a>. The difference being <code class="xref py py-class docutils literal notranslate">IntFlag</code> members can be combined

using the bitwise operators (&, |, ^, ~) and the result is still an

<code class="xref py py-class docutils literal notranslate">IntFlag</code> member, if possible. Like <a class="reference internal" href="../library/enum.html#enum.IntEnum" title="enum.IntEnum"><code class="xref py py-class docutils literal notranslate">IntEnum</code></a>, <code class="xref py py-class docutils literal notranslate">IntFlag</code>

members are also integers and can be used wherever an <code class="xref py py-class docutils literal notranslate">int</code> is used.

توجه

Any operation on an <a class="reference internal" href="../library/enum.html#enum.IntFlag" title="enum.IntFlag"><code class="xref py py-class docutils literal notranslate">IntFlag</code></a> member besides the bit-wise operations will

lose the <code class="xref py py-class docutils literal notranslate">IntFlag</code> membership.

Bit-wise operations that result in invalid <a class="reference internal" href="../library/enum.html#enum.IntFlag" title="enum.IntFlag"><code class="xref py py-class docutils literal notranslate">IntFlag</code></a> values will lose the

<code class="xref py py-class docutils literal notranslate">IntFlag</code> membership. See <a class="reference internal" href="../library/enum.html#enum.FlagBoundary" title="enum.FlagBoundary"><code class="xref py py-class docutils literal notranslate">FlagBoundary</code></a> for

details.

</div>

Added in version 3.6.

</div>

تغییر داده شده در نسخه 3.11.

</div>

Sample <a class="reference internal" href="../library/enum.html#enum.IntFlag" title="enum.IntFlag"><code class="xref py py-class docutils literal notranslate">IntFlag</code></a> class:

>>> class Perm(IntFlag):

... R = 4

... W = 2

... X = 1

...

>>> Perm.R | Perm.W

<Perm.R|W: 6>

>>> Perm.R + Perm.W

6

>>> RW = Perm.R | Perm.W

>>> Perm.R in RW

True

</pre></div>

</div>

It is also possible to name the combinations:

<div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> class Perm(IntFlag):

... R = 4

... W = 2

... X = 1

... RWX = 7

...

>>> Perm.RWX

<Perm.RWX: 7>

>>> ~Perm.RWX

<Perm: 0>

>>> Perm(7)

<Perm.RWX: 7>

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