Enum raises AttributeError: 'dict' object has no attribute '_member_names'

user_13686796 0
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I am trying to create an Enum class dynamically, using type(name, base, dict).

from enum import Enum

class FriendlyEnum(Enum):
    def hello(self):
        print(self.name + ' says hello!')

The normal way works fine:

class MyEnum(FriendlyEnum):
    foo = 1
    bar = 2

MyEnum.foo.hello()

# ->
foo says hello!

But if I try dynamically:

MyEnum = type('MyEnum',
    (FriendlyEnum,),
    {'foo':1,'bar':2}
)

MyEnum.foo.hello()

# ->
File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/enum.py", line 146, in __new__
enum_members = {k: classdict[k] for k in classdict._member_names}
AttributeError: 'dict' object has no attribute '_member_names'

Any suggestions?

It might be useful for testing the methods of a parent Enum class, dynamically creating new Enum classes with different attributes and same inherited methods.

enums python
2 Answers

The Enum class can be called to dynamically create a new Enum type. This will also work for subclasses of Enum

MyEnum = FriendlyEnum('MyEnum', {'foo': 1, 'bar': 2})
MyEnum.foo.hello()
user_5485620

An explanation of why it's not working: EnumMeta is expecting the class dictionary (classdict above) to be an instance of enum._EnumDict, but what you gave it was a normal dict (hence no _member_names attribute).

Using type to directly create an enum is not supported -- use the method outlined by Iain Shelvington instead.

user_2088800
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