How can I attach documentation to members of a python enum?

@Eric has shown how to do it using the stdlib Enum; this is how to do it using aenum¹:

from aenum import Enum  # or IntEnum


class Color(Enum):                     # or IntEnum

    _init_ = 'value __doc__'

    RED = 1, 'The color red'
    GREEN = 2, 'The color green'
    BLUE = 3, 'The color blue'

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¹ Disclosure: I am the author of the Python stdlib Enum, the enum34 backport, and the Advanced Enumeration (aenum) library.

You can override Enum.__new__ to take a doc argument as follows:

class DocEnum(Enum):
    def __new__(cls, value, doc=None):
        self = object.__new__(cls)  # calling super().__new__(value) here would fail
        self._value_ = value
        if doc is not None:
            self.__doc__ = doc
        return self

Which can be used as:

class Color(DocEnum):
    """ Some colors """
    RED   = 1, "The color red"
    GREEN = 2, "The color green"
    BLUE  = 3, "The color blue. These docstrings are more useful in the real example"

Which in IPython, gives the following:

In [17]: Color.RED?
Type:            Color
String form:     Color.RED
Docstring:       The color red
Class docstring: Some colors

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This can also be made to work for IntEnum:

class DocIntEnum(IntEnum):
    def __new__(cls, value, doc=None):
        self = int.__new__(cls, value)  # calling super().__new__(value) here would fail
        self._value_ = value
        if doc is not None:
            self.__doc__ = doc
        return self