Fix some set algebra methods of WeakSet objects.
diff --git a/Lib/_weakrefset.py b/Lib/_weakrefset.py
index b8d8043..ff613e6 100644
--- a/Lib/_weakrefset.py
+++ b/Lib/_weakrefset.py
@@ -123,26 +123,14 @@
self.update(other)
return self
- # Helper functions for simple delegating methods.
- def _apply(self, other, method):
- if not isinstance(other, self.__class__):
- other = self.__class__(other)
- newdata = method(other.data)
- newset = self.__class__()
- newset.data = newdata
- return newset
-
def difference(self, other):
- return self._apply(other, self.data.difference)
+ newset = self.copy()
+ newset.difference_update(other)
+ return newset
__sub__ = difference
def difference_update(self, other):
- if self._pending_removals:
- self._commit_removals()
- if self is other:
- self.data.clear()
- else:
- self.data.difference_update(ref(item) for item in other)
+ self.__isub__(other)
def __isub__(self, other):
if self._pending_removals:
self._commit_removals()
@@ -153,13 +141,11 @@
return self
def intersection(self, other):
- return self._apply(other, self.data.intersection)
+ return self.__class__(item for item in other if item in self)
__and__ = intersection
def intersection_update(self, other):
- if self._pending_removals:
- self._commit_removals()
- self.data.intersection_update(ref(item) for item in other)
+ self.__iand__(other)
def __iand__(self, other):
if self._pending_removals:
self._commit_removals()
@@ -186,27 +172,24 @@
return self.data == set(ref(item) for item in other)
def symmetric_difference(self, other):
- return self._apply(other, self.data.symmetric_difference)
+ newset = self.copy()
+ newset.symmetric_difference_update(other)
+ return newset
__xor__ = symmetric_difference
def symmetric_difference_update(self, other):
- if self._pending_removals:
- self._commit_removals()
- if self is other:
- self.data.clear()
- else:
- self.data.symmetric_difference_update(ref(item) for item in other)
+ self.__ixor__(other)
def __ixor__(self, other):
if self._pending_removals:
self._commit_removals()
if self is other:
self.data.clear()
else:
- self.data.symmetric_difference_update(ref(item) for item in other)
+ self.data.symmetric_difference_update(ref(item, self._remove) for item in other)
return self
def union(self, other):
- return self._apply(other, self.data.union)
+ return self.__class__(e for s in (self, other) for e in s)
__or__ = union
def isdisjoint(self, other):