From 6fafa878f6968af3041ae7265f0ef11854bb254f Mon Sep 17 00:00:00 2001
From: "Paul \"LeoNerd\" Evans" <paul@matrix.org>
Date: Mon, 18 Aug 2014 16:07:14 +0100
Subject: Deny __iter__ on UserID/RoomID/RoomName instances as it's a subtle
 bug that will bite you

---
 synapse/types.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/synapse/types.py b/synapse/types.py
index 054b1e713c..b8e191bb3c 100644
--- a/synapse/types.py
+++ b/synapse/types.py
@@ -32,6 +32,12 @@ class DomainSpecificString(
             HomeServer as being its own
     """
 
+    # Deny iteration because it will bite you if you try to create a singleton
+    # set by:
+    #    users = set(user)
+    def __iter__(self):
+        raise ValueError("Attempted to iterate a %s" % (type(self).__name__))
+
     @classmethod
     def from_string(cls, s, hs):
         """Parse the string given by 's' into a structure object."""
-- 
cgit 1.4.1