我创建了以下枚举:
from enum import Enum
class Action(str, Enum):
NEW_CUSTOMER = "new_customer"
LOGIN = "login"
BLOCK = "block"
我也继承自str
,所以我可以做以下事情:
action = "new_customer"
...
if action == Action.NEW_CUSTOMER:
...
我现在希望能够检查此Enum中是否有字符串,例如:
if "new_customer" in Action:
....
我尝试将以下方法添加到类中:
def __contains__(self, item):
return item in [i for i in self]
但是,当我运行此代码时:
print("new_customer" in [i for i in Action])
print("new_customer" in Action)
我得到这个异常:
True
Traceback (most recent call last):
File "/Users/kevinobrien/Documents/Projects/crazywall/utils.py", line 24, in <module>
print("new_customer" in Action)
File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/enum.py", line 310, in __contains__
raise TypeError(
TypeError: unsupported operand type(s) for 'in': 'str' and 'EnumMeta'
今天我碰到了这个问题。我不得不为Python 3.8更改许多子包。
也许是以下其他解决方案的替代方案,其灵感来自此处对类似问题的出色答案以及此页面上@MadPhysicist的答案:
class MetaEnum(EnumMeta):
def __contains__(cls, item):
try:
cls(item)
except ValueError:
return False
return True
class BaseEnum(Enum, metaclass=MetaEnum):
pass
class Stuff(BaseEnum):
foo = 1
bar = 5
测试(在py37或38中):
>>> 1 in Stuff
True
>>> Stuff.foo in Stuff
True
>>> 2 in Stuff
False
>>> 2.3 in Stuff
False
>>> 'zero' in Stuff
False
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