is it possible to directly import an enum field in Python 3?

Question

Let's say I have the following enum:

class LineStyle(Enum):
    SOLID = 'solid'
    DASHED = 'dashed'
    DASHDOT = 'dashdot'
    DOTTED = 'dotted'

Is it possible to somehow directly import fields from this enum ?

Eg:

from mymodule.LineStyle import SOLID, DASHED  # does not work

The only workaround I could think of is declaring all enums fields as module variables:

class LineStyle(Enum):
    SOLID = 'solid'
    DASHED = 'dashed'
    DASHDOT = 'dashdot'
    DOTTED = 'dotted'

SOLID = LineStyle.SOLID
DASHED = LineStyle.DASHED
DASHDOT = LineStyle.DASHDOT
DOTTED = LineStyle.DOTTED

Is there a more elegant way to do this ?

Answer 1

No. With import can only ever add references in the current namespace pointing to the module object itself, or to the top-level names in the module. Enum values are not top-level names in the module unless you explicitly put them there, like in your workaround.

You can automate assigning those names to globals, by adding all information from the __members__ attribute to your module globals:

globals().update(LineStyle.__members__)

The globals() function gives you a reference to the namespace of the current module, letting you add names to that namespace dynamically. The LineStyle.__members__ attribute is a a mapping of name to value (including aliases), so the above adds all names to the global namespace:

>>> from enum import Enum
>>> class LineStyle(Enum):
...     SOLID = 'solid'
...     DASHED = 'dashed'
...     DASHDOT = 'dashdot'
...     DOTTED = 'dotted'
...
>>> SOLID
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'SOLID' is not defined
>>> globals().update(LineStyle.__members__)
>>> SOLID
<LineStyle.SOLID: 'solid'>

If you don't want aliases included in that, use a for loop, iterating over the LineStyle object. That only gives you the member objects, from which you can then pull the name:

for member in LineStyle:
    globals()[member.name] = member

Answer 2

You cannot directly import an enum member, but you can use a decorator to auto-add the Enum members to globals(), which would then be importable. For example:

def global(enum):
    globals().update(enum.__members__)
    return enum


@global
class LineStyle(Enum):
    SOLID = 'solid'
    DASHED = 'dashed'
    DASHDOT = 'dashdot'
    DOTTED = 'dotted'