Patch by Keir Mierle so that sets can be compared to other objects that know
authorGuido van Rossum <guido@python.org>
Thu, 23 Aug 2007 23:57:24 +0000 (23:57 +0000)
committerGuido van Rossum <guido@python.org>
Thu, 23 Aug 2007 23:57:24 +0000 (23:57 +0000)
how to compare themselves to sets.  (Prep work for making dict views more
set-like.)

Lib/test/test_set.py
Objects/setobject.c

index df72fb2da634c61844c6515b93cf61217d98df93..3b8e747ea4f659ae901ecbec5d139a97e35d5168 100644 (file)
@@ -492,6 +492,42 @@ class TestSet(TestJointOps):
         s = None
         self.assertRaises(ReferenceError, str, p)
 
+    def test_rich_compare(self):
+        class TestRichSetCompare:
+            def __gt__(self, some_set):
+                self.gt_called = True
+                return False
+            def __lt__(self, some_set):
+                self.lt_called = True
+                return False
+            def __ge__(self, some_set):
+                self.ge_called = True
+                return False
+            def __le__(self, some_set):
+                self.le_called = True
+                return False
+
+        # This first tries the bulitin rich set comparison, which doesn't know
+        # how to handle the custom object. Upon returning NotImplemented, the
+        # corresponding comparison on the right object is invoked.
+        myset = {1, 2, 3}
+
+        myobj = TestRichSetCompare()
+        myset < myobj
+        self.assert_(myobj.gt_called)
+
+        myobj = TestRichSetCompare()
+        myset > myobj
+        self.assert_(myobj.lt_called)
+
+        myobj = TestRichSetCompare()
+        myset <= myobj
+        self.assert_(myobj.ge_called)
+
+        myobj = TestRichSetCompare()
+        myset >= myobj
+        self.assert_(myobj.le_called)
+
     # C API test only available in a debug build
     if hasattr(set, "test_c_api"):
         def test_c_api(self):
index 7ff27b1f70457ce949f435ca0a41c790293eb5fd..079f404db8e4efef88b7c3711d08db1d9cc97899 100644 (file)
@@ -1607,12 +1607,8 @@ set_richcompare(PySetObject *v, PyObject *w, int op)
        PyObject *r1, *r2;
 
        if(!PyAnySet_Check(w)) {
-               if (op == Py_EQ)
-                       Py_RETURN_FALSE;
-               if (op == Py_NE)
-                       Py_RETURN_TRUE;
-               PyErr_SetString(PyExc_TypeError, "can only compare to a set");
-               return NULL;
+               Py_INCREF(Py_NotImplemented);
+               return Py_NotImplemented;
        }
        switch (op) {
        case Py_EQ: