diff -r 34881ee3eec5 Lib/tempfile.py
--- a/Lib/tempfile.py	Mon Jun 16 11:14:47 2014 -0500
+++ b/Lib/tempfile.py	Mon Jun 16 20:57:16 2014 -0300
@@ -383,7 +383,6 @@
     def __init__(self, file, name, delete=True):
         self.file = file
         self.name = name
-        self.delete = delete
         self._closer = _TemporaryFileCloser(file, name, delete)
 
     def __getattr__(self, name):
@@ -428,6 +427,13 @@
     def __iter__(self):
         return iter(self.file)
 
+    @property
+    def delete(self):
+        return self._closer.delete
+    @delete.setter
+    def delete(self, value):
+        self._closer.delete = value
+
 
 def NamedTemporaryFile(mode='w+b', buffering=-1, encoding=None,
                        newline=None, suffix="", prefix=template,
diff -r 34881ee3eec5 Lib/test/test_tempfile.py
--- a/Lib/test/test_tempfile.py	Mon Jun 16 11:14:47 2014 -0500
+++ b/Lib/test/test_tempfile.py	Mon Jun 16 20:57:16 2014 -0300
@@ -741,6 +741,38 @@
                 os.unlink(tmp)
             os.rmdir(dir)
 
+    def test_property_del_on_close(self):
+        # Tests that delete-on-close can be enabled if property delete is True
+        # issue21579
+        dir = tempfile.mkdtemp()
+        try:
+            f = tempfile.NamedTemporaryFile(dir=dir, delete=False)
+            f.delete = True
+            f.write(b'blat')
+            f.close()
+            self.assertFalse(os.path.exists(f.name),
+                        "NamedTemporaryFile %s exists after close" % f.name)
+        finally:
+            os.rmdir(dir)
+
+    def test_property_dis_del_on_close(self):
+        # Tests that delete-on-close can be disabled if property delete is False
+        # issue21579
+        dir = tempfile.mkdtemp()
+        tmp = None
+        try:
+            f = tempfile.NamedTemporaryFile(dir=dir)
+            f.delete = False
+            tmp = f.name
+            f.write(b'blat')
+            f.close()
+            self.assertTrue(os.path.exists(f.name),
+                        "NamedTemporaryFile %s missing after close" % f.name)
+        finally:
+            if tmp is not None:
+                os.unlink(tmp)
+            os.rmdir(dir)
+
     def test_multiple_close(self):
         # A NamedTemporaryFile can be closed many times without error
         f = tempfile.NamedTemporaryFile()