From: Tim Peters <tim.peters@gmail.com>
Date: Fri, 8 Nov 2002 05:26:52 +0000 (+0000)
Subject: _update():  Commented the new obscurity.  Materialized into a tuple
X-Git-Tag: v2.3c1~3522
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=0ec1ddcdcfaef4a4525f3f8a26d59804deef767d;p=thirdparty%2FPython%2Fcpython.git

_update():  Commented the new obscurity.  Materialized into a tuple
instead of into a list for a bit of speed/space savings.  Reopened the
bug report too (628246), as I'm unclear on why we don't sort out the
cause of the TypeError instead.
---

diff --git a/Lib/sets.py b/Lib/sets.py
index bbb93a091ebd..5a66a2e0a661 100644
--- a/Lib/sets.py
+++ b/Lib/sets.py
@@ -319,10 +319,16 @@ class BaseSet(object):
             data.update(iterable)
             return
 
-        value = True
+        # If the mere process of iterating may raise TypeError, materialize
+        # the iterable into a tuple first.  Then the TypeError will get
+        # raised here and propagated back to the caller.  Once we get into
+        # the loop following, TypeError is assumed to mean that element
+        # can't be used as a dict key.
         if type(iterable) not in (list, tuple, dict, file, xrange, str):
-            iterable = list(iterable)
+            iterable = tuple(iterable)
+
         it = iter(iterable)
+        value = True
         while True:
             try:
                 for element in it: