Kaydet (Commit) 322daea7 authored tarafından Raymond Hettinger's avatar Raymond Hettinger

Issue 1818: collections.namedtuple() to support automatic renaming of invalid fieldnames.

üst c5eba1e4
......@@ -617,7 +617,7 @@ 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
......@@ -635,6 +635,11 @@ they add the ability to access fields by name instead of position index.
a :mod:`keyword` such as *class*, *for*, *return*, *global*, *pass*, *print*,
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
......@@ -642,6 +647,9 @@ they add the ability to access fields by name instead of position index.
.. versionadded:: 2.6
.. versionchanged:: 2.7
added support for *rename*.
Example:
.. doctest::
......
......@@ -16,7 +16,7 @@ from itertools import repeat as _repeat, chain as _chain, starmap as _starmap, i
### 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')
......@@ -45,6 +45,16 @@ def namedtuple(typename, field_names, verbose=False):
if isinstance(field_names, basestring):
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)
......@@ -54,7 +64,7 @@ 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)
......
......@@ -44,6 +44,17 @@ class TestNamedTuple(unittest.TestCase):
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)
......
......@@ -155,6 +155,10 @@ 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 #5170: Fixed Unicode output bug in logging and added test case.
......
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