Binary operators such as __eq__, __and__, etc. should return NotImplemented in the event that the given argument is an unsupported type rather than raising an error. This allows the other object to patch in its own implementation.
Roughly speaking, it means code should be written like this:
from typing import Iterable
class SortedSet:
def __and__(self, other):
if isinstance(other, Iterable): # Or `hasattr(type(other), "__iter__")`.
return self.intersection(other)
else:
return NotImplemented # `self & other` then checks `other.__and__(self)`.This allows cases such as this:
class Interval: # Not a set e.g. does not contain `__iter__`.
def __and__(self, other):
if isinstance(other, Interval):
...
elif isinstance(other, Iterable):
return {x for x in other if x in self}
else:
return NotImplemented
def __contains__(self, other):
...
sorted_set & interval # Expected set, got TypeError.
Binary operators such as
__eq__,__and__, etc. shouldreturn NotImplementedin the event that the given argument is an unsupported type rather than raising an error. This allows the other object to patch in its own implementation.Roughly speaking, it means code should be written like this:
This allows cases such as this: