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Eliminate camelcase function name

This commit is contained in:
Raymond Hettinger 2007-10-08 21:26:58 +00:00
parent 814b04600c
commit a48a29947a
4 changed files with 50 additions and 36 deletions
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44
Doc/library/collections.rst
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@ -12,7 +12,7 @@
This module implements high-performance container datatypes. Currently,
there are two datatypes, :class:`deque` and :class:`defaultdict`, and
one datatype factory function, :func:`NamedTuple`. Python already
one datatype factory function, :func:`named_tuple`. Python already
includes built-in containers, :class:`dict`, :class:`list`,
:class:`set`, and :class:`tuple`. In addition, the optional :mod:`bsddb`
module has a :meth:`bsddb.btopen` method that can be used to create in-memory
@ -25,7 +25,7 @@ ordered dictionaries.
Added :class:`defaultdict`.
.. versionchanged:: 2.6
Added :class:`NamedTuple`.
Added :func:`named_tuple`.
.. _deque-objects:
@ -348,14 +348,14 @@ Setting the :attr:`default_factory` to :class:`set` makes the
.. _named-tuple-factory:
:func:`NamedTuple` Factory Function for Tuples with Named Fields
----------------------------------------------------------------
:func:`named_tuple` Factory Function for Tuples with Named Fields
-----------------------------------------------------------------
Named tuples assign meaning to each position in a tuple and allow for more readable,
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, fieldnames, [verbose])
.. function:: named_tuple(typename, fieldnames, [verbose])
Returns a new tuple subclass named *typename*. The new subclass is used to
create tuple-like objects that have fields accessable by attribute lookup as
@ -363,22 +363,22 @@ they add the ability to access fields by name instead of position index.
helpful docstring (with typename and fieldnames) and a helpful :meth:`__repr__`
method which lists the tuple contents in a ``name=value`` format.
The *fieldnames* are a single string with each fieldname separated by a space
and/or comma (for example "x y" or "x, y"). Alternately, the *fieldnames*
can be specified as list or tuple of strings. Any valid Python identifier
may be used for a fieldname except for names starting and ending with double
underscores.
The *fieldnames* are a single string with each fieldname separated by whitespace
and/or commas (for example 'x y' or 'x, y'). Alternatively, the *fieldnames*
can be specified as a list of strings (such as ['x', 'y']). Any valid
Python identifier may be used for a fieldname except for names starting and
ending with double underscores.
If *verbose* is true, will print the class definition.
*NamedTuple* instances do not have per-instance dictionaries, so they are
Named tuple instances do not have per-instance dictionaries, so they are
lightweight and require no more memory than regular tuples.
.. versionadded:: 2.6
Example::
>>> Point = NamedTuple('Point', 'x y', verbose=True)
>>> Point = named_tuple('Point', 'x y', verbose=True)
class Point(tuple):
'Point(x, y)'
__slots__ = ()
@ -410,27 +410,35 @@ Example::
Named tuples are especially useful for assigning field names to result tuples returned
by the :mod:`csv` or :mod:`sqlite3` modules::
EmployeeRecord = named_tuple('EmployeeRecord', 'name, age, title, department, paygrade')
from itertools import starmap
import csv
EmployeeRecord = NamedTuple('EmployeeRecord', 'name age title department paygrade')
for emp in starmap(EmployeeRecord, csv.reader(open("employees.csv", "rb"))):
print emp.name, emp.title
When casting a single record to a *NamedTuple*, use the star-operator [#]_ to unpack
import sqlite3
conn = sqlite3.connect('/companydata')
cursor = conn.cursor()
cursor.execute('SELECT name, age, title, department, paygrade FROM employees')
for emp in starmap(EmployeeRecord, cursor.fetchall()):
print emp.name, emp.title
When casting a single record to a named tuple, use the star-operator [#]_ to unpack
the values::
>>> t = [11, 22]
>>> Point(*t) # the star-operator unpacks any iterable object
Point(x=11, y=22)
When casting a dictionary to a *NamedTuple*, use the double-star-operator::
When casting a dictionary to a named tuple, use the double-star-operator::
>>> d = {'x': 11, 'y': 22}
>>> Point(**d)
Point(x=11, y=22)
In addition to the methods inherited from tuples, named tuples support
additonal methods and a read-only attribute.
two additonal methods and a read-only attribute.
.. method:: somenamedtuple.__asdict__()
@ -464,8 +472,8 @@ additonal methods and a read-only attribute.
>>> p.__fields__ # view the field names
('x', 'y')
>>> Color = NamedTuple('Color', 'red green blue')
>>> Pixel = NamedTuple('Pixel', Point.__fields__ + Color.__fields__)
>>> Color = named_tuple('Color', 'red green blue')
>>> Pixel = named_tuple('Pixel', Point.__fields__ + Color.__fields__)
>>> Pixel(11, 22, 128, 255, 0)
Pixel(x=11, y=22, red=128, green=255, blue=0)'

14
Lib/collections.py
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@ -1,13 +1,13 @@
__all__ = ['deque', 'defaultdict', 'NamedTuple']
__all__ = ['deque', 'defaultdict', 'named_tuple']
from _collections import deque, defaultdict
from operator import itemgetter as _itemgetter
import sys as _sys
def NamedTuple(typename, field_names, verbose=False):
def named_tuple(typename, field_names, verbose=False):
"""Returns a new subclass of tuple with named fields.
>>> Point = NamedTuple('Point', 'x y')
>>> Point = named_tuple('Point', 'x y')
>>> Point.__doc__ # docstring for the new class
'Point(x, y)'
>>> p = Point(11, y=22) # instantiate with positional args or keywords
@ -36,6 +36,10 @@ def NamedTuple(typename, field_names, verbose=False):
raise ValueError('Type names and field names can only contain alphanumeric characters and underscores')
if any(name.startswith('__') and name.endswith('__') for name in field_names):
raise ValueError('Field names cannot start and end with double underscores')
if any(name[:1].isdigit() for name in field_names):
raise ValueError('Field names cannot start with a number')
if len(field_names) != len(set(field_names)):
raise ValueError('Encountered duplicate field name')
# Create and fill-in the class template
argtxt = repr(field_names).replace("'", "")[1:-1] # tuple repr without parens or quotes
@ -83,10 +87,10 @@ def NamedTuple(typename, field_names, verbose=False):
if __name__ == '__main__':
# verify that instances can be pickled
from cPickle import loads, dumps
Point = NamedTuple('Point', 'x, y', True)
Point = named_tuple('Point', 'x, y', True)
p = Point(x=10, y=20)
assert p == loads(dumps(p))
import doctest
TestResults = NamedTuple('TestResults', 'failed attempted')
TestResults = named_tuple('TestResults', 'failed attempted')
print TestResults(*doctest.testmod())

26
Lib/test/test_collections.py
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@ -1,23 +1,25 @@
import unittest
from test import test_support
from collections import NamedTuple
from collections import named_tuple
class TestNamedTuple(unittest.TestCase):
def test_factory(self):
Point = NamedTuple('Point', 'x y')
Point = named_tuple('Point', 'x y')
self.assertEqual(Point.__name__, 'Point')
self.assertEqual(Point.__doc__, 'Point(x, y)')
self.assertEqual(Point.__slots__, ())
self.assertEqual(Point.__module__, __name__)
self.assertEqual(Point.__getitem__, tuple.__getitem__)
self.assertRaises(ValueError, NamedTuple, 'abc%', 'def ghi')
self.assertRaises(ValueError, NamedTuple, 'abc', 'def g%hi')
self.assertRaises(ValueError, NamedTuple, 'abc', '__def__ ghi')
NamedTuple('Point0', 'x1 y2') # Verify that numbers are allowed in names
self.assertRaises(ValueError, named_tuple, 'abc%', 'def ghi')
self.assertRaises(ValueError, named_tuple, 'abc', 'def g%hi')
self.assertRaises(ValueError, named_tuple, 'abc', '__def__ ghi')
self.assertRaises(ValueError, named_tuple, 'abc', 'def def ghi')
self.assertRaises(ValueError, named_tuple, 'abc', '8def 9ghi')
named_tuple('Point0', 'x1 y2') # Verify that numbers are allowed in names
def test_instance(self):
Point = NamedTuple('Point', 'x y')
Point = named_tuple('Point', 'x y')
p = Point(11, 22)
self.assertEqual(p, Point(x=11, y=22))
self.assertEqual(p, Point(11, y=22))
@ -36,17 +38,17 @@ class TestNamedTuple(unittest.TestCase):
self.assertEqual(p.__asdict__(), dict(x=11, y=22)) # test __dict__ method
# verify that field string can have commas
Point = NamedTuple('Point', 'x, y')
Point = named_tuple('Point', 'x, y')
p = Point(x=11, y=22)
self.assertEqual(repr(p), 'Point(x=11, y=22)')
# verify that fieldspec can be a non-string sequence
Point = NamedTuple('Point', ('x', 'y'))
Point = named_tuple('Point', ('x', 'y'))
p = Point(x=11, y=22)
self.assertEqual(repr(p), 'Point(x=11, y=22)')
def test_tupleness(self):
Point = NamedTuple('Point', 'x y')
Point = named_tuple('Point', 'x y')
p = Point(11, 22)
self.assert_(isinstance(p, tuple))
@ -66,9 +68,9 @@ class TestNamedTuple(unittest.TestCase):
def test_odd_sizes(self):
Zero = NamedTuple('Zero', '')
Zero = named_tuple('Zero', '')
self.assertEqual(Zero(), ())
Dot = NamedTuple('Dot', 'd')
Dot = named_tuple('Dot', 'd')
self.assertEqual(Dot(1), (1,))
def test_main(verbose=None):

2
Misc/NEWS
View File

@ -544,7 +544,7 @@ Library
- Added heapq.merge() for merging sorted input streams.
- Added collections.NamedTuple() for assigning field names to tuples.
- Added collections.named_tuple() for assigning field names to tuples.
- Added itertools.izip_longest().