Add error-checking to namedtuple's _replace() method.
diff --git a/Lib/collections.py b/Lib/collections.py
index 2a58b86..9985f93 100644
--- a/Lib/collections.py
+++ b/Lib/collections.py
@@ -78,7 +78,10 @@
return {%(dicttxt)s} \n
def _replace(self, **kwds):
'Return a new %(typename)s object replacing specified fields with new values'
- return self.__class__._make(map(kwds.get, %(field_names)r, self)) \n\n''' % locals()
+ result = self.__class__._make(map(kwds.pop, %(field_names)r, self))
+ if kwds:
+ raise ValueError('Got unexpected field names: %%r' %% kwds.keys())
+ return result \n\n''' % locals()
for i, name in enumerate(field_names):
template += ' %s = property(itemgetter(%d))\n' % (name, i)
if verbose: