Merged revisions 69466,69480 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk

........
  r69466 | raymond.hettinger | 2009-02-09 12:39:41 -0600 (Mon, 09 Feb 2009) | 3 lines

  Issue 5171: itertools.product docstring missing 'repeat' argument
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  r69480 | raymond.hettinger | 2009-02-09 19:24:05 -0600 (Mon, 09 Feb 2009) | 1 line

  Issue 1818: collections.namedtuple() to support automatic renaming of invalid fieldnames.
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diff --git a/Lib/collections.py b/Lib/collections.py
index 512cf28..f8392b6 100644
--- a/Lib/collections.py
+++ b/Lib/collections.py
@@ -18,7 +18,7 @@
 ### namedtuple
 ################################################################################
 
-def namedtuple(typename, field_names, verbose=False):
+def namedtuple(typename, field_names, verbose=False, rename=False):
     """Returns a new subclass of tuple with named fields.
 
     >>> Point = namedtuple('Point', 'x y')
@@ -47,6 +47,16 @@
     if isinstance(field_names, str):
         field_names = field_names.replace(',', ' ').split() # names separated by whitespace and/or commas
     field_names = tuple(map(str, field_names))
+    if rename:
+        names = list(field_names)
+        seen = set()
+        for i, name in enumerate(names):
+            if (not all(c.isalnum() or c=='_' for c in name) or _iskeyword(name)
+                or not name or name[0].isdigit() or name.startswith('_')
+                or name in seen):
+                names[i] = '_%d' % (i+1)
+            seen.add(name)
+        field_names = tuple(names)
     for name in (typename,) + field_names:
         if not all(c.isalnum() or c=='_' for c in name):
             raise ValueError('Type names and field names can only contain alphanumeric characters and underscores: %r' % name)
@@ -56,7 +66,7 @@
             raise ValueError('Type names and field names cannot start with a number: %r' % name)
     seen_names = set()
     for name in field_names:
-        if name.startswith('_'):
+        if name.startswith('_') and not rename:
             raise ValueError('Field names cannot start with an underscore: %r' % name)
         if name in seen_names:
             raise ValueError('Encountered duplicate field name: %r' % name)