| """Utilities for defining models |
| """ |
| |
| import operator |
| |
| |
| class KeyBasedCompareMixin(object): |
| """Provides comparison capabilities that is based on a key |
| """ |
| |
| 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) |
