Validate that __length_hint__ returns a usable result.

raymond.hettinger · raymond.hettinger · commit adcd11ee60bc · 2009-02-03T02:12:10.000Z
git-svn-id: http://svn.python.org/projects/python/branches/py3k@69234 6015fed2-1504-0410-9fe1-9d1591cc4771
diff --git a/Lib/test/test_iterlen.py b/Lib/test/test_iterlen.py
@@ -208,6 +208,11 @@ def __iter__(self): return iter(range(10))
     def __length_hint__(self):
         raise RuntimeError('hello')
 
+class NoneLengthHint(object):
+    def __iter__(self): return iter(range(10))
+    def __length_hint__(self):
+        return None
+
 class TestLengthHintExceptions(unittest.TestCase):
 
     def test_issue1242657(self):
@@ -219,6 +224,11 @@ def test_issue1242657(self):
         self.assertRaises(RuntimeError, b.extend, BadLen())
         self.assertRaises(RuntimeError, b.extend, BadLengthHint())
 
+    def test_invalid_hint(self):
+        # Make sure an invalid result doesn't muck-up the works
+        self.assertEqual(list(NoneLengthHint()), list(range(10)))
+
+
 def test_main():
     unittests = [
         TestRepeat,
diff --git a/Objects/abstract.c b/Objects/abstract.c
@@ -105,7 +105,7 @@ _PyObject_LengthHint(PyObject *o, Py_ssize_t defaultvalue)
 		PyErr_Clear();
 		return defaultvalue;
 	}
-	rv = PyLong_AsSsize_t(ro);
+	rv = PyLong_Check(ro) ? PyLong_AsSsize_t(ro) : defaultvalue;
 	Py_DECREF(ro);
 	return rv;
 }

Original file line number	Diff line number	Diff line change
`@@ -105,7 +105,7 @@ _PyObject_LengthHint(PyObject *o, Py_ssize_t defaultvalue)`
`105`	`105`	`PyErr_Clear();`
`106`	`106`	`return defaultvalue;`
`107`	`107`	`}`
`108`		`- rv = PyLong_AsSsize_t(ro);`
	`108`	`+ rv = PyLong_Check(ro) ? PyLong_AsSsize_t(ro) : defaultvalue;`
`109`	`109`	`Py_DECREF(ro);`
`110`	`110`	`return rv;`
`111`	`111`	`}`