Errors

Exception contract

Operation	Exception
d[missing_key]	KeyError
d.missing_attr	AttributeError
del d.missing_attr	AttributeError (documented deviation)
del d["missing_key"]	KeyError
d[unhashable_key]	TypeError
hash(d)	TypeError (unhashable, like dict)

Example messages

AttributeDict["missing"]
# KeyError: 'missing'

AttributeDict.missing
# AttributeError: 'attributedict._attributedict.AttributeDict' object has no attribute 'missing'

The C implementation never leaves a stale exception after a successful operation; PyErr_Clear is used only where an exception is intentionally swallowed and re-raised with a different type (e.g. the del d.missing → AttributeError deviation).

Unhashable

AttributeDict is unhashable, like dict :

hash(AttributeDict) # TypeError: unhashable type: '...AttributeDict'