Multi-arg form for set.difference() and set.difference_update().
authorRaymond Hettinger <python@rcn.com>
Wed, 11 Jun 2008 10:30:54 +0000 (10:30 +0000)
committerRaymond Hettinger <python@rcn.com>
Wed, 11 Jun 2008 10:30:54 +0000 (10:30 +0000)
Doc/library/stdtypes.rst
Lib/test/test_set.py
Misc/NEWS
Objects/setobject.c

index 758ee7bd63710d26dd2605e91135d6834efe4e06..64d3c32f397c7c557045ddc671a7d1b243c7139c 100644 (file)
@@ -1583,10 +1583,13 @@ The constructors for both classes work the same:
       .. versionchanged:: 2.6
          Accepts multiple input iterables.
 
-   .. method:: difference(other)
-               set - other
+   .. method:: difference(other, ...)
+               set - other - ...
 
-      Return a new set with elements in the set that are not in *other*.
+      Return a new set with elements in the set that are not in the others.
+
+      .. versionchanged:: 2.6
+         Accepts multiple input iterables.
 
    .. method:: symmetric_difference(other)
                set ^ other
@@ -1650,10 +1653,13 @@ The constructors for both classes work the same:
       .. versionchanged:: 2.6
          Accepts multiple input iterables.
 
-   .. method:: difference_update(other)
-               set -= other
+   .. method:: difference_update(other, ...)
+               set -= other | ...
 
-      Update the set, removing elements found in *other*.
+      Update the set, removing elements found in others.
+
+      .. versionchanged:: 2.6
+         Accepts multiple input iterables.
 
    .. method:: symmetric_difference_update(other)
                set ^= other
index b32d953a84fdbe087af4bc0f98895778e3645499..1b01954108e848ae5440a9503ddc2ffd15cb20b9 100644 (file)
@@ -149,6 +149,8 @@ class TestJointOps(unittest.TestCase):
             self.assertEqual(self.thetype('abcba').difference(C('efgfe')), set('abc'))
             self.assertEqual(self.thetype('abcba').difference(C('ccb')), set('a'))
             self.assertEqual(self.thetype('abcba').difference(C('ef')), set('abc'))
+            self.assertEqual(self.thetype('abcba').difference(), set('abc'))
+            self.assertEqual(self.thetype('abcba').difference(C('a'), C('b')), set('c'))
 
     def test_sub(self):
         i = self.s.difference(self.otherword)
@@ -467,6 +469,18 @@ class TestSet(TestJointOps):
                 self.assertEqual(s.difference_update(C(p)), None)
                 self.assertEqual(s, set(q))
 
+                s = self.thetype('abcdefghih')
+                s.difference_update()
+                self.assertEqual(s, self.thetype('abcdefghih'))
+
+                s = self.thetype('abcdefghih')
+                s.difference_update(C('aba'))
+                self.assertEqual(s, self.thetype('cdefghih'))
+
+                s = self.thetype('abcdefghih')
+                s.difference_update(C('cdc'), C('aba'))
+                self.assertEqual(s, self.thetype('efghih'))
+
     def test_isub(self):
         self.s -= set(self.otherword)
         for c in (self.word + self.otherword):
index f721122363f4c639031c4b8c275adaaae8bd1c39..afaf05b39c7af244c102bf51ba3b2ec01c23b934 100644 (file)
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -13,7 +13,7 @@ Core and Builtins
 -----------------
 
 - Several set methods now accept multiple arguments:  update(), union(),
-  intersection() and intersection_update().
+  intersection(), intersection_update(), difference(), and difference_update().
 
 - Issue #2898: Added sys.getsizeof() to retrieve size of objects in bytes.
 
index 1127680c071f0ea14440129ad6a7601deebc7ca8..f3eea21745a7698e78e2993a07c8ae087cfca742 100644 (file)
@@ -1495,11 +1495,16 @@ set_difference_update_internal(PySetObject *so, PyObject *other)
 }
 
 static PyObject *
-set_difference_update(PySetObject *so, PyObject *other)
+set_difference_update(PySetObject *so, PyObject *args)
 {
-       if (set_difference_update_internal(so, other) != -1)
-               Py_RETURN_NONE;
-       return NULL;
+       Py_ssize_t i;
+
+       for (i=0 ; i<PyTuple_GET_SIZE(args) ; i++) {
+               PyObject *other = PyTuple_GET_ITEM(args, i);
+               if (set_difference_update_internal(so, other) == -1)
+                       return NULL;
+       }
+       Py_RETURN_NONE;
 }
 
 PyDoc_STRVAR(difference_update_doc,
@@ -1557,10 +1562,34 @@ set_difference(PySetObject *so, PyObject *other)
        return result;
 }
 
+static PyObject *
+set_difference_multi(PySetObject *so, PyObject *args)
+{
+       Py_ssize_t i;
+       PyObject *result, *other;
+
+       if (PyTuple_GET_SIZE(args) == 0)
+               return set_copy(so);
+
+       other = PyTuple_GET_ITEM(args, 0);
+       result = set_difference(so, other);
+       if (result == NULL)
+               return NULL;
+
+       for (i=1 ; i<PyTuple_GET_SIZE(args) ; i++) {
+               other = PyTuple_GET_ITEM(args, i);
+               if (set_difference_update_internal((PySetObject *)result, other) == -1) {
+                       Py_DECREF(result);
+                       return NULL;
+               }
+       }
+       return result;
+}
+
 PyDoc_STRVAR(difference_doc,
-"Return the difference of two sets as a new set.\n\
+"Return the difference of two or more sets as a new set.\n\
 \n\
-(i.e. all elements that are in this set but not the other.)");
+(i.e. all elements that are in this set but not the others.)");
 static PyObject *
 set_sub(PySetObject *so, PyObject *other)
 {
@@ -1574,16 +1603,12 @@ set_sub(PySetObject *so, PyObject *other)
 static PyObject *
 set_isub(PySetObject *so, PyObject *other)
 {
-       PyObject *result;
-
        if (!PyAnySet_Check(other)) {
                Py_INCREF(Py_NotImplemented);
                return Py_NotImplemented;
        }
-       result = set_difference_update(so, other);
-       if (result == NULL)
+       if (set_difference_update_internal(so, other) == -1)
                return NULL;
-       Py_DECREF(result);
        Py_INCREF(so);
        return (PyObject *)so;
 }
@@ -1978,9 +2003,9 @@ static PyMethodDef set_methods[] = {
         copy_doc},
        {"discard",     (PyCFunction)set_discard,       METH_O,
         discard_doc},
-       {"difference",  (PyCFunction)set_difference,    METH_O,
+       {"difference",  (PyCFunction)set_difference_multi,      METH_VARARGS,
         difference_doc},
-       {"difference_update",   (PyCFunction)set_difference_update,     METH_O,
+       {"difference_update",   (PyCFunction)set_difference_update,     METH_VARARGS,
         difference_update_doc},
        {"intersection",(PyCFunction)set_intersection_multi,    METH_VARARGS,
         intersection_doc},
@@ -2107,7 +2132,7 @@ static PyMethodDef frozenset_methods[] = {
         contains_doc},
        {"copy",        (PyCFunction)frozenset_copy,    METH_NOARGS,
         copy_doc},
-       {"difference",  (PyCFunction)set_difference,    METH_O,
+       {"difference",  (PyCFunction)set_difference_multi,      METH_VARARGS,
         difference_doc},
        {"intersection",(PyCFunction)set_intersection_multi,    METH_VARARGS,
         intersection_doc},