Issue #13872: socket.detach() now marks the socket closed (as mirrored in the socket repr()).

Patch by Matt Joiner.

Lib/socket.py

@@ -199,6 +199,17 @@ class socket(_socket.socket):
         if self._io_refs <= 0:
             self._real_close()
 
+    def detach(self):
+        """detach() -> file descriptor
+
+        Close the socket object without closing the underlying file descriptor.
+        The object cannot be used after this call, but the file descriptor
+        can be reused for other purposes.  The file descriptor is returned.
+        """
+        self._closed = True
+        return super().detach()
+
+
 def fromfd(fd, family, type, proto=0):
     """ fromfd(fd, family, type[, proto]) -> socket object
 

Lib/test/test_socket.py

@@ -1574,6 +1574,7 @@ class BasicTCPTest(SocketConnectedTest):
         f = self.cli_conn.detach()
         self.assertEqual(f, fileno)
         # cli_conn cannot be used anymore...
+        self.assertTrue(self.cli_conn._closed)
         self.assertRaises(socket.error, self.cli_conn.recv, 1024)
         self.cli_conn.close()
         # ...but we can create another socket using the (still open)

Misc/NEWS

@@ -37,6 +37,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #13872: socket.detach() now marks the socket closed (as mirrored
+  in the socket repr()).  Patch by Matt Joiner.
+
 - Issue #14406: Fix a race condition when using ``concurrent.futures.wait(
   return_when=ALL_COMPLETED)``.  Patch by Matt Joiner.