10.2. Enum IntEnum

  • List of finite choices

  • Enumerations

  • IntEnum

  • Flag

  • IntFlag

10.2.1. IntEnum

>>> from enum import IntEnum
>>>
>>>
>>> class Color(IntEnum):
...     RED = 1
...     GREEN = 2
...     BLUE = 3
>>>
>>>
>>> mycolor = Color.RED
>>>
>>> mycolor.name
'RED'
>>>
>>> mycolor.value
1

10.2.2. Auto

>>> from enum import IntEnum, auto
>>>
>>>
>>> class Color(IntEnum):
...     RED = auto()
...     GREEN = auto()
...     BLUE = auto()
>>>
>>> for color in Color:
...     print(color.name, color.value)
...
RED 1
GREEN 2
BLUE 3

10.2.3. Use Case - 1

>>> from enum import Enum, IntEnum
>>>
>>>
>>> class HTTPStatus(Enum):
...     OK = 200
...     CREATED = 201
...     BAD_REQUEST = 400
...     NOT_FOUND = 404
...     INTERNAL_ERROR = 500

10.2.4. Use Case - 2

>>> from enum import Enum, IntEnum
>>>
>>>
>>> class Status(IntEnum):
...     FULL_HEALTH = 100
...     DEAD = 0

>>> hit_points = 100
>>> Status(hit_points)
<Status.FULL_HEALTH: 100>

>>> hit_points = 0
>>> Status(hit_points)
<Status.DEAD: 0>

10.2.5. Use Case - 3

>>> from enum import Enum, IntEnum
>>>
>>>
>>> class IndexDrives(IntEnum):
...     ControlWord = 0x6040
...     StatusWord = 0x6041
...     OperationMode = 0x6060

10.2.6. Use Case - 4

../../_images/enum-usecase-keycodes.png

Note, keycodes can vary depending on operating system and programming language used [mskeycodes], [jskeycodes].

>>> class Key(Enum):
...     ESC = 0x01
...     ARROW_LEFT = 0x61
...     ARROW_UP = 0x57
...     ARROW_RIGHT = 0x63
...     ARROW_DOWN = 0x62

10.2.7. Use Case - 5

  • r - read

  • w - write

  • x - execute

  • rwx - read, write, execute; 0b111 == 0o7

  • rw- - read, write; 0b110 == 0o6

  • r-x - read, execute; 0b101 == 0o5

  • r-- - read only; 0b100 == 0o4

  • rwxr-xr-- - user=(read,write,execute); group=(read,execute); others=(read)

  • https://docs.python.org/3/library/os.html#os.stat

>>> from enum import Enum
>>> from pathlib import Path
>>>
>>>
>>> class Permission(Enum):
...     READ_WRITE_EXECUTE = 0b111
...     READ_WRITE = 0b110
...     READ_EXECUTE = 0b101
...     READ = 0b100
...     WRITE_EXECUTE = 0b011
...     WRITE = 0b010
...     EXECUTE = 0b001
...     NONE = 0b000
>>>
>>>
>>> file = Path('/tmp/myfile.txt')
>>> file.touch()
>>> file.stat()  
os.stat_result(st_mode=33188, st_ino=98480473, st_dev=16777220,
               st_nlink=1, st_uid=501, st_gid=20, st_size=0,
               st_atime=1624458230, st_mtime=1624458230,
               st_ctime=1624458230)
>>>
>>> permissions = file.stat().st_mode
>>> decimal = int(permissions)
>>> octal = oct(permissions)
>>> binary = bin(permissions)
>>> print(f'{decimal=}, {octal=}, {binary}')
decimal=33188, octal='0o100644', 0b1000000110100100
>>>
>>> *_, user, group, others = oct(permissions)
>>> print(f'{user=} {group=} {others=}')
user='6' group='4' others='4'
>>>
>>> Permission(int(user))
<Permission.READ_WRITE: 6>
>>>
>>> Permission(int(group))
<Permission.READ: 4>
>>>
>>> Permission(int(others))
<Permission.READ: 4>
>>>
>>> file.unlink()

10.2.8. References