Add error-checking to namedtuple's _replace() method.
diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
index 34c3118..eaa823a 100644
--- a/Doc/library/collections.rst
+++ b/Doc/library/collections.rst
@@ -410,7 +410,10 @@
def _replace(self, **kwds):
'Return a new Point object replacing specified fields with new values'
- return self.__class__._make(map(kwds.get, ('x', 'y'), self))
+ result = self.__class__._make(map(kwds.pop, ('x', 'y'), self))
+ if kwds:
+ raise ValueError('Got unexpected field names: %r' % kwds.keys())
+ return result
x = property(itemgetter(0))
y = property(itemgetter(1))
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:
diff --git a/Lib/test/test_collections.py b/Lib/test/test_collections.py
index c17b76d..dd9982a 100644
--- a/Lib/test/test_collections.py
+++ b/Lib/test/test_collections.py
@@ -55,6 +55,13 @@
self.assertEqual(p._replace(x=1), (1, 22)) # test _replace method
self.assertEqual(p._asdict(), dict(x=11, y=22)) # test _asdict method
+ try:
+ p._replace(x=1, error=2)
+ except ValueError:
+ pass
+ else:
+ self._fail('Did not detect an incorrect fieldname')
+
# verify that field string can have commas
Point = namedtuple('Point', 'x, y')
p = Point(x=11, y=22)