Merged revisions 69466,69480 via svnmerge from

benjaminp · benjaminp · commit a86f2c06fd08 · 2009-02-10T02:41:10.000Z
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
........
  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.
........
diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
@@ -597,7 +597,7 @@ Named tuples assign meaning to each position in a tuple and allow for more reada
 self-documenting code.  They can be used wherever regular tuples are used, and
 they add the ability to access fields by name instead of position index.
 
-.. function:: namedtuple(typename, field_names, [verbose])
+.. function:: namedtuple(typename, field_names, [verbose], [rename])
 
    Returns a new tuple subclass named *typename*.  The new subclass is used to
    create tuple-like objects that have fields accessible by attribute lookup as
@@ -615,11 +615,19 @@ they add the ability to access fields by name instead of position index.
    a :mod:`keyword` such as *class*, *for*, *return*, *global*, *pass*,
    or *raise*.
 
+   If *rename* is true, invalid fieldnames are automatically replaced
+   with positional names.  For example, ``['abc', 'def', 'ghi', 'abc']`` is
+   converted to ``['abc', '_2', 'ghi', '_4']``, eliminating the keyword
+   ``def`` and the duplicate fieldname ``abc``.
+
    If *verbose* is true, the class definition is printed just before being built.
 
    Named tuple instances do not have per-instance dictionaries, so they are
    lightweight and require no more memory than regular tuples.
 
+   .. versionchanged:: 2.7
+      added support for *rename*.
+
 Example:
 
 .. doctest::
diff --git 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 @@ def namedtuple(typename, field_names, verbose=False):
     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 @@ def namedtuple(typename, field_names, verbose=False):
             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)
diff --git a/Lib/test/test_collections.py b/Lib/test/test_collections.py
@@ -47,6 +47,17 @@ def test_factory(self):
         self.assertRaises(TypeError, Point._make, [11])                     # catch too few args
         self.assertRaises(TypeError, Point._make, [11, 22, 33])             # catch too many args
 
+    def test_name_fixer(self):
+        for spec, renamed in [
+            [('efg', 'g%hi'),  ('efg', '_2')],                              # field with non-alpha char
+            [('abc', 'class'), ('abc', '_2')],                              # field has keyword
+            [('8efg', '9ghi'), ('_1', '_2')],                               # field starts with digit
+            [('abc', '_efg'), ('abc', '_2')],                               # field with leading underscore
+            [('abc', 'efg', 'efg', 'ghi'), ('abc', 'efg', '_3', 'ghi')],    # duplicate field
+            [('abc', '', 'x'), ('abc', '_2', 'x')],                         # fieldname is a space
+        ]:
+            self.assertEqual(namedtuple('NT', spec, rename=True)._fields, renamed)
+
     def test_instance(self):
         Point = namedtuple('Point', 'x y')
         p = Point(11, 22)
diff --git a/Misc/NEWS b/Misc/NEWS
@@ -170,6 +170,10 @@ Library
 - Issue #5122: Synchronize tk load failure check to prevent a potential
   deadlock.
 
+- Issue #1818: collections.namedtuple() now supports a keyword argument
+  'rename' which lets invalid fieldnames be automatically converted to
+  positional names in the form, _1, _2, ...
+
 - Issue #4890: Handle empty text search pattern in Tkinter.Text.search.
 
 - Issue #4512 (part 2): Promote ``ZipImporter._get_filename()`` to be a
diff --git a/Modules/itertoolsmodule.c b/Modules/itertoolsmodule.c
@@ -1791,6 +1791,9 @@ For example, product(A, B) returns the same as:  ((x,y) for x in A for y in B).\
 The leftmost iterators are in the outermost for-loop, so the output tuples\n\
 cycle in a manner similar to an odometer (with the rightmost element changing\n\
 on every iteration).\n\n\
+To compute the product of an iterable with itself, specify the number\n\
+of repetitions with the optional repeat keyword argument. For example,\n\
+product(A, repeat=4) means the same as product(A, A, A, A).\n\n\
 product('ab', range(3)) --> ('a',0) ('a',1) ('a',2) ('b',0) ('b',1) ('b',2)\n\
 product((0,1), (0,1), (0,1)) --> (0,0,0) (0,0,1) (0,1,0) (0,1,1) (1,0,0) ...");
 
