5.3. Enum Auto

5.3. Enum Auto — Python

auto()
Automatically generated value
Care must be taken if mixing auto() with manually specified values.
If used, the Enum machinery will call an Enum._generate_next_value_() to get an appropriate value.
Enum._generate_next_value_() can be overridden to customize the values used by auto.

5.3.1. StrEnum

Automatically generated string values
By default: lower-cased version of the member's name

>>> from enum import StrEnum, auto
>>>
>>>
>>> class Color(StrEnum):
...     RED = auto()    # 'red'
...     GREEN = auto()  # 'green'
...     BLUE = auto()   # 'blue'
>>>
>>> for color in Color:
...     print(f'color: {color.name}, value: {color.value}')
...
color: RED, value: red
color: GREEN, value: green
color: BLUE, value: blue

5.3.2. IntEnum

Automatically generated integer values
By default: last value plus one

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

5.3.3. Flag

Automatically generated power-of-two values
By default: first power-of-two greater than the last value

>>> from enum import Flag, auto
>>>
>>>
>>> class Color(Flag):
...     RED = auto()    # 1 (0b001)
...     GREEN = auto()  # 2 (0b010)
...     BLUE = auto()   # 4 (0b100)
>>>
>>>
>>> for color in Color:
...     print(f'color: {color.name}, value: {color.value}')
...
color: RED, value: 1
color: GREEN, value: 2
color: BLUE, value: 4

5.3.4. Assignments

# %% About
# - Name: Enum Auto 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` and `auto()`
# 3. 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` i `auto()`
# 3. 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, auto

# %% Types
Color: type[StrEnum]

# %% Data

# %% Result

# %% About
# - Name: Enum Auto 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` and `auto()`
# 3. 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` i `auto()`
# 3. 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 `Color` has an invalid type; expected: `IntEnum`.'

>>> 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, auto

# %% Types
Color: type[IntEnum]

# %% Data

# %% Result