• Enum

  • StrEnum

  • IntEnum

  • Flag

5.2.1. Enum

>>> from enum import Enum
>>>
>>>
>>> class Color(Enum):
...     RED = 1
...     GREEN = '#00FF00'
...     BLUE = (0, 0, 255)

5.2.2. StrEnum

>>> from enum import StrEnum
>>>
>>>
>>> class Color(StrEnum):
...     RED = 'red'
...     GREEN = 'green'
...     BLUE = 'blue'

5.2.3. IntEnum

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

5.2.4. Flag

  • Flag

  • Values needs to be power-of-two's (1, 2, 4, 8, 16, ...)

  • Cannot have duplicated names

>>> from enum import Flag
>>>
>>> class Color(Flag):
...     RED = 1
...     GREEN = 2
...     BLUE = 4
>>>
>>>
>>> mycolor = Color(3)
>>> mycolor
<Color.RED|GREEN: 3>

5.2.5. Case Study

Recap:

$ ls -l README.txt
-rw-r--r-- 1 alice staff 4.0K 2000-01-01 00:00 README.txt

  • user = rw- = 0b110 = 6

  • group = r-- = 0b100 = 4

  • others = r-- = 0b100 = 4

SetUp:

>>> from enum import Flag

Definition:

>>> class Permission(Flag):
...     READ = 0b100
...     WRITE = 0b010
...     EXECUTE = 0b001

Usage:

>>> Permission(1)
<Permission.EXECUTE: 1>
>>>
>>> Permission(2)
<Permission.WRITE: 2>
>>>
>>> Permission(3)
<Permission.WRITE|EXECUTE: 3>
>>>
>>> Permission(4)
<Permission.READ: 4>
>>>
>>> Permission(5)
<Permission.READ|EXECUTE: 5>
>>>
>>> Permission(6)
<Permission.READ|WRITE: 6>
>>>
>>> Permission(7)
<Permission.READ|WRITE|EXECUTE: 7>

Example:

>>> permission = Permission.READ | Permission.WRITE
>>> permission
<Permission.READ|WRITE: 6>

5.2.6. Use Case - 1

>>> from enum import StrEnum
>>>
>>>
>>> class Color(StrEnum):
...     RED = '#FF0000'
...     GREEN = '#00FF00'
...     BLUE = '#0000FF'

5.2.7. Use Case - 2

>>> from enum import StrEnum
>>>
>>>
>>> class Direction(StrEnum):
...     NORTH = 'N'
...     SOUTH = 'S'
...     EAST = 'E'
...     WEST = 'W'

5.2.8. Use Case - 3

>>> from enum import StrEnum
>>>
>>>
>>> class Status(StrEnum):
...     ALIVE = 'alive'
...     DEAD = 'dead'

5.2.9. Use Case - 4

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

5.2.10. Assignments

# %% About
# - Name: Enum Types StrEnum
# - Difficulty: easy
# - Lines: 4
# - Minutes: 2

# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author

# %% English
# 1. Define enum `Color`:
# - name: RED, value: 'red'
# - name: GREEN, value: 'green'
# - name: BLUE, value: 'blue'
# 2. Use `StrEnum`
# 3. Do not use `auto()`
# 4. Run doctests - all must succeed

# %% Polish
# 1. Zdefiniuj enum `Color`:
# - nazwa: RED, wartość: 'red'
# - nazwa: GREEN, wartość: 'green'
# - nazwa: BLUE, wartość: 'blue'
# 2. Użyj `StrEnum`
# 3. Nie używaj `auto()`
# 4. Uruchom doctesty - wszystkie muszą się powieść

# %% Expected
# >>> Color.RED.value
# 'red'
#
# >>> Color.GREEN.value
# 'green'
#
# >>> Color.BLUE.value
# 'blue'

# %% Doctests
"""
>>> import sys; sys.tracebacklimit = 0

>>> assert sys.version_info >= (3, 9), \
'Python has an is invalid version; expected: `3.9` or newer.'

>>> assert StrEnum in Color.mro(), \
'Color must be an StrEnum'

>>> assert len(Color) == 3, \
'Variable `Color` has an invalid length; expected: `3`.'

>>> assert hasattr(Color, 'RED'), \
'Object `Color` has an invalid attribute; expected: to have an attribute `RED`.'

>>> assert hasattr(Color, 'GREEN'), \
'Object `Color` has an invalid attribute; expected: to have an attribute `GREEN`.'

>>> assert hasattr(Color, 'BLUE'), \
'Object `Color` has an invalid attribute; expected: to have an attribute `BLUE`.'


>>> assert Color.RED.value == 'red'

>>> assert Color.GREEN.value == 'green'

>>> assert Color.BLUE.value == 'blue'
"""

# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -f -v myfile.py`

# %% Imports
from enum import StrEnum

# %% Types
Color: type[StrEnum]

# %% Data

# %% Result


# %% About
# - Name: Enum Types IntEnum
# - Difficulty: easy
# - Lines: 4
# - Minutes: 2

# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author

# %% English
# 1. Define enum `Color`:
# - name: RED, value: 1
# - name: GREEN, value: 2
# - name: BLUE, value: 3
# 2. Use `IntEnum`
# 3. Do not use `auto()`
# 4. Run doctests - all must succeed

# %% Polish
# 1. Zdefiniuj enum `Color`:
# - nazwa: RED, wartość: 1
# - nazwa: GREEN, wartość: 2
# - nazwa: BLUE, wartość: 3
# 2. Użyj `IntEnum`
# 3. Nie używaj `auto()`
# 4. Uruchom doctesty - wszystkie muszą się powieść

# %% Expected
# >>> Color.RED.value
# 1
#
# >>> Color.GREEN.value
# 2
#
# >>> Color.BLUE.value
# 3

# %% Doctests
"""
>>> import sys; sys.tracebacklimit = 0

>>> assert sys.version_info >= (3, 9), \
'Python has an is invalid version; expected: `3.9` or newer.'

>>> assert IntEnum in Color.mro(), \
'Class `IntEnum` has an invalid type; expected: `Enum`.'

>>> assert len(Color) == 3, \
'Variable `Color` has an invalid length; expected: `3`.'

>>> assert hasattr(Color, 'RED'), \
'Object `Color` has an invalid attribute; expected: to have an attribute `RED`.'

>>> assert hasattr(Color, 'GREEN'), \
'Object `Color` has an invalid attribute; expected: to have an attribute `GREEN`.'

>>> assert hasattr(Color, 'BLUE'), \
'Object `Color` has an invalid attribute; expected: to have an attribute `BLUE`.'


>>> assert Color.RED.value == 1
>>> assert Color.GREEN.value == 2
>>> assert Color.BLUE.value == 3
"""

# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -f -v myfile.py`

# %% Imports
from enum import IntEnum

# %% Types
Color: type[IntEnum]

# %% Data

# %% Result


# %% About
# - Name: Enum Types Flag
# - Difficulty: easy
# - Lines: 4
# - Minutes: 3

# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author

# %% English
# 1. Define enum `Color`:
# - name: RED, value: 1
# - name: GREEN, value: 2
# - name: BLUE, value: 4
# 2. Use `Flag`
# 3. Run doctests - all must succeed

# %% Polish
# 1. Zdefiniuj enum `Color`:
# - nazwa: RED, wartość: 1
# - nazwa: GREEN, wartość: 2
# - nazwa: BLUE, wartość: 4
# 2. Użyj `Flag`
# 3. Uruchom doctesty - wszystkie muszą się powieść

# %% Expected
# >>> Color.RED.value
# 1
#
# >>> Color.GREEN.value
# 2
#
# >>> Color.BLUE.value
# 4

# %% Doctests
"""
>>> import sys; sys.tracebacklimit = 0

>>> assert sys.version_info >= (3, 9), \
'Python has an is invalid version; expected: `3.9` or newer.'

>>> assert Flag in Color.mro(), \
'Color must be an Flag'

>>> assert len(Color) == 3, \
'Variable `Color` has an invalid length; expected: `3`.'

>>> assert hasattr(Color, 'RED'), \
'Object `Color` has an invalid attribute; expected: to have an attribute `RED`.'

>>> assert hasattr(Color, 'GREEN'), \
'Object `Color` has an invalid attribute; expected: to have an attribute `GREEN`.'

>>> assert hasattr(Color, 'BLUE'), \
'Object `Color` has an invalid attribute; expected: to have an attribute `BLUE`.'


>>> assert Color.RED.value == 1
>>> assert Color.GREEN.value == 2
>>> assert Color.BLUE.value == 4
"""

# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -f -v myfile.py`

# %% Imports
from enum import Flag

# %% Types
Color: type[Flag]

# %% Data

# %% Result