bpo-44605: Teach @total_ordering() to work with metaclasses (GH-27633)

Author: rhettinger

Lib/functools.py

@@ -88,84 +88,84 @@ def wraps(wrapped,
 
 def _gt_from_lt(self, other, NotImplemented=NotImplemented):
  'Return a > b. Computed by @total_ordering from (not a < b) and (a != b).'
- op_result = self.__lt__(other)
+ op_result = type(self).__lt__(self, other)
  if op_result is NotImplemented:
  return op_result
  return not op_result and self != other
 
 def _le_from_lt(self, other, NotImplemented=NotImplemented):
  'Return a <= b. Computed by @total_ordering from (a < b) or (a == b).'
- op_result = self.__lt__(other)
+ op_result = type(self).__lt__(self, other)
  if op_result is NotImplemented:
  return op_result
  return op_result or self == other
 
 def _ge_from_lt(self, other, NotImplemented=NotImplemented):
  'Return a >= b. Computed by @total_ordering from (not a < b).'
- op_result = self.__lt__(other)
+ op_result = type(self).__lt__(self, other)
  if op_result is NotImplemented:
  return op_result
  return not op_result
 
 def _ge_from_le(self, other, NotImplemented=NotImplemented):
  'Return a >= b. Computed by @total_ordering from (not a <= b) or (a == b).'
- op_result = self.__le__(other)
+ op_result = type(self).__le__(self, other)
  if op_result is NotImplemented:
  return op_result
  return not op_result or self == other
 
 def _lt_from_le(self, other, NotImplemented=NotImplemented):
  'Return a < b. Computed by @total_ordering from (a <= b) and (a != b).'
- op_result = self.__le__(other)
+ op_result = type(self).__le__(self, other)
  if op_result is NotImplemented:
  return op_result
  return op_result and self != other
 
 def _gt_from_le(self, other, NotImplemented=NotImplemented):
  'Return a > b. Computed by @total_ordering from (not a <= b).'
- op_result = self.__le__(other)
+ op_result = type(self).__le__(self, other)
  if op_result is NotImplemented:
  return op_result
  return not op_result
 
 def _lt_from_gt(self, other, NotImplemented=NotImplemented):
  'Return a < b. Computed by @total_ordering from (not a > b) and (a != b).'
- op_result = self.__gt__(other)
+ op_result = type(self).__gt__(self, other)
  if op_result is NotImplemented:
  return op_result
  return not op_result and self != other
 
 def _ge_from_gt(self, other, NotImplemented=NotImplemented):
  'Return a >= b. Computed by @total_ordering from (a > b) or (a == b).'
- op_result = self.__gt__(other)
+ op_result = type(self).__gt__(self, other)
  if op_result is NotImplemented:
  return op_result
  return op_result or self == other
 
 def _le_from_gt(self, other, NotImplemented=NotImplemented):
  'Return a <= b. Computed by @total_ordering from (not a > b).'
- op_result = self.__gt__(other)
+ op_result = type(self).__gt__(self, other)
  if op_result is NotImplemented:
  return op_result
  return not op_result
 
 def _le_from_ge(self, other, NotImplemented=NotImplemented):
  'Return a <= b. Computed by @total_ordering from (not a >= b) or (a == b).'
- op_result = self.__ge__(other)
+ op_result = type(self).__ge__(self, other)
  if op_result is NotImplemented:
  return op_result
  return not op_result or self == other
 
 def _gt_from_ge(self, other, NotImplemented=NotImplemented):
  'Return a > b. Computed by @total_ordering from (a >= b) and (a != b).'
- op_result = self.__ge__(other)
+ op_result = type(self).__ge__(self, other)
  if op_result is NotImplemented:
  return op_result
  return op_result and self != other
 
 def _lt_from_ge(self, other, NotImplemented=NotImplemented):
  'Return a < b. Computed by @total_ordering from (not a >= b).'
- op_result = self.__ge__(other)
+ op_result = type(self).__ge__(self, other)
  if op_result is NotImplemented:
  return op_result
  return not op_result

Lib/test/test_functools.py

@@ -1163,6 +1163,34 @@ def test_pickle(self):
  method_copy = pickle.loads(pickle.dumps(method, proto))
  self.assertIs(method_copy, method)
 
+
+ def test_total_ordering_for_metaclasses_issue_44605(self):
+
+ @functools.total_ordering
+ class SortableMeta(type):
+ def __new__(cls, name, bases, ns):
+ return super().__new__(cls, name, bases, ns)
+
+ def __lt__(self, other):
+ if not isinstance(other, SortableMeta):
+ pass
+ return self.__name__ < other.__name__
+
+ def __eq__(self, other):
+ if not isinstance(other, SortableMeta):
+ pass
+ return self.__name__ == other.__name__
+
+ class B(metaclass=SortableMeta):
+ pass
+
+ class A(metaclass=SortableMeta):
+ pass
+
+ self.assertTrue(A < B)
+ self.assertFalse(A > B)
+
+
 @functools.total_ordering
 class Orderable_LT:
  def __init__(self, value):

Misc/NEWS.d/next/Library/2021-08-06-09-43-50.bpo-44605.q4YSBZ.rst

@@ -0,0 +1 @@
+The @functools.total_ordering() decorator now works with metaclasses.