"""Utilities for defining models
"""
# The following comment should be removed at some point in the future.
# mypy: disallow-untyped-defs=False
import operator
class KeyBasedCompareMixin(object):
"""Provides comparison capabilities that is based on a key
"""
__slots__ = ['_compare_key', '_defining_class']
def __init__(self, key, defining_class):
self._compare_key = key
self._defining_class = defining_class
def __hash__(self):
return hash(self._compare_key)
def __lt__(self, other):
return self._compare(other, operator.__lt__)
def __le__(self, other):
return self._compare(other, operator.__le__)
def __gt__(self, other):
return self._compare(other, operator.__gt__)
def __ge__(self, other):
return self._compare(other, operator.__ge__)
def __eq__(self, other):
return self._compare(other, operator.__eq__)
def __ne__(self, other):
return self._compare(other, operator.__ne__)
def _compare(self, other, method):
if not isinstance(other, self._defining_class):
return NotImplemented
return method(self._compare_key, other._compare_key)
