backports.strenum 1.1.1

Base class for creating enumerated constants that are also subclasses of str

A backport of (copy and paste from) python 3.10’s StrEnum class for >=3.8.6:

Base class for creating enumerated constants that are also subclasses of str.

See the design discussion, and Ethan Furman’s first and second PR with this implementation.

A slightly different implementation would likely be compatible with lower python versions; PRs are welcome if they pass the test suite. The existing (reference) implementation should still be the one used on supported versions.

Install with pip install backports.strenum, and use with:

try:
    # be ready for 3.10 when it drops
    from enum import StrEnum
except ImportError:
    from backports.strenum import StrEnum

class MyStrEnum(StrEnum):
    POTATO = "potato"
    ORANGE = "orange"
    SPADE = "spade"

MyStrEnum.POTATO == "potato"  # True
MyStrEnum.ORANGE.upper() == "ORANGE"  # True
str(MyStrEnum.SPADE) == "spade"  # True

---

StrEnum

The second variation of Enum that is provided is also a subclass of str. Members of a StrEnum can be compared to strings; by extension, string enumerations of different types can also be compared to each other. StrEnum exists to help avoid the problem of getting an incorrect member:

>>> class Directions(StrEnum):
...     NORTH = 'north',    # notice the trailing comma
...     SOUTH = 'south'

Before StrEnum, Directions.NORTH would have been the tuple ('north',).

Note

Unlike other Enum’s, str(StrEnum.member) will return the value of the member instead of the usual "EnumClass.member".

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Creating members that are mixed with other data types

When subclassing other data types, such as int or str, with an Enum, all values after the = are passed to that data type’s constructor. For example:

>>> class MyEnum(IntEnum):
...     example = '11', 16      # '11' will be interpreted as a hexadecimal
...                             # number
>>> MyEnum.example
<MyEnum.example: 17>

---

StrEnum and str.__str__

An important difference between StrEnum and other Enums is the __str__ method; because StrEnum members are strings, some parts of Python will read the string data directly, while others will call str(). To make those two operations have the same result, StrEnum.__str__ will be the same as str.__str__ so that str(StrEnum.member) == StrEnum.member is true.