python中的奇怪枚举行为

Question

I have the following enum(it is truncated to make the examples cleaner)

class ObjectNames(enum.Enum):
    full = 'full'

And this one:

class ObjectPoses(enum.Enum):
    front = 'front'
    left = 'left'
    right = 'right'

This two enums are tied with the following relation:

class ObjectNamePoseMatcher:
    match = {
        ObjectNames.full: [ObjectPoses.front, ObjectPoses.right, ObjectPoses.left],
}

So it basically creates a relation between an ObjectName and a pose. This is the setup. At some point my code fails with KeyError when trying to make ObjectNamePoseMatcher.match lookup. Specifically, it fails with this error message:

KeyError: <ObjectNames.full: 'full'> It fails here:

ObjectNamePoseMatcher.match[self._object_name] ,

however

>>self._object_name
<ObjectNames.full: 'full'>

and

>>ObjectNamePoseMatcher.match {<ObjectNames.full: 'full'>: [<ObjectPoses.front: 'front'>, <ObjectPoses.right: 'right'>, <ObjectPoses.left: 'left'>]}

So the key is there. This is strange so I executed the following snippet:

for k,v in ObjectNamePoseMatcher.match.items():
    print(k,k==self.object_name)
    print(hash(k)==hash(self.object_name))
    print(id(k)==id(self.object_name))
    print(id(type(k))==id(type(self.object_name)))

And this results in: ObjectNames.full False True False False So ObjectNames.full and self._object_name have the same hash, but different types, id and type ids. But hash is the same.

After this I went to the very first place where self._object_name field is set. Executed the same snippet again, got the same result. I executed this snippet after this line:

d.object_name = ObjectNames.full However if at this breakpoint I re-execute this line

d.object_name = ObjectNames.full and then execute the aforementioned snippet I get the following output:

ObjectNames.full True True True True So now hash, ids and type ids match! For no reson, I just re-executed the same line after stopping at breakpoint.

What could possibly go wrong here?

Thanks

Answer 1

I think you want IntEnum not Enum . IntEnum s compare by integer values and so by transitivity to other unrelated enumerations. You're clearly expecting instances of ObjectNames and ObjectPoses to be comparable and I don't think Enum s work like that.