diff options
-rw-r--r-- | Doc/lib/libcollections.tex | 19 | ||||
-rw-r--r-- | Lib/collections.py | 47 | ||||
-rw-r--r-- | Lib/test/test_collections.py | 3 |
3 files changed, 40 insertions, 29 deletions
diff --git a/Doc/lib/libcollections.tex b/Doc/lib/libcollections.tex index 443a7a4..c0eb6ec 100644 --- a/Doc/lib/libcollections.tex +++ b/Doc/lib/libcollections.tex @@ -378,14 +378,25 @@ Point(x=11, y=22) The use cases are the same as those for tuples. The named factories assign meaning to each tuple position and allow for more readable, self-documenting code. Named tuples can also be used to assign field names - to tuples - returned by the \module{csv} or \module{sqlite3} modules. For example: + to tuples returned by the \module{csv} or \module{sqlite3} modules. + For example: \begin{verbatim} +from itertools import starmap import csv EmployeeRecord = NamedTuple('EmployeeRecord', 'name age title department paygrade') -for tup in csv.reader(open("employees.csv", "rb")): - print EmployeeRecord(*tup) +for record in starmap(EmployeeRecord, csv.reader(open("employees.csv", "rb"))): + print record +\end{verbatim} + + To cast an individual record stored as \class{list}, \class{tuple}, or some other + iterable type, use the star-operator to unpack the values: + + \begin{verbatim} +>>> Color = NamedTuple('Color', 'name code') +>>> m = dict(red=1, green=2, blue=3) +>>> print Color(*m.popitem()) +Color(name='blue', code=3) \end{verbatim} \end{funcdesc} diff --git a/Lib/collections.py b/Lib/collections.py index 6e816dc..adba81c 100644 --- a/Lib/collections.py +++ b/Lib/collections.py @@ -24,30 +24,29 @@ def NamedTuple(typename, s): """ field_names = s.split() - nargs = len(field_names) - - def __new__(cls, *args, **kwds): - if kwds: - try: - args += tuple(kwds[name] for name in field_names[len(args):]) - except KeyError, name: - raise TypeError('%s missing required argument: %s' % (typename, name)) - if len(args) != nargs: - raise TypeError('%s takes exactly %d arguments (%d given)' % (typename, nargs, len(args))) - return tuple.__new__(cls, args) - - repr_template = '%s(%s)' % (typename, ', '.join('%s=%%r' % name for name in field_names)) - - m = dict(vars(tuple)) # pre-lookup superclass methods (for faster lookup) - m.update(__doc__= '%s(%s)' % (typename, ', '.join(field_names)), - __slots__ = (), # no per-instance dict (so instances are same size as tuples) - __new__ = __new__, - __repr__ = lambda self, _format=repr_template.__mod__: _format(self), - __module__ = _sys._getframe(1).f_globals['__name__'], - ) - m.update((name, property(_itemgetter(index))) for index, name in enumerate(field_names)) - - return type(typename, (tuple,), m) + assert ''.join(field_names).replace('_', '').isalpha() # protect against exec attacks + argtxt = ', '.join(field_names) + reprtxt = ', '.join('%s=%%r' % name for name in field_names) + template = '''class %(typename)s(tuple): + '%(typename)s(%(argtxt)s)' + __slots__ = () + def __new__(cls, %(argtxt)s): + return tuple.__new__(cls, (%(argtxt)s,)) + def __repr__(self): + return '%(typename)s(%(reprtxt)s)' %% self + ''' % locals() + for i, name in enumerate(field_names): + template += '\t%s = property(itemgetter(%d))\n' % (name, i) + m = dict(itemgetter=_itemgetter) + exec template in m + result = m[typename] + if hasattr(_sys, '_getframe'): + result.__module__ = _sys._getframe(1).f_globals['__name__'] + return result + + + + if __name__ == '__main__': diff --git a/Lib/test/test_collections.py b/Lib/test/test_collections.py index a139129..b3f460e 100644 --- a/Lib/test/test_collections.py +++ b/Lib/test/test_collections.py @@ -11,7 +11,6 @@ class TestNamedTuple(unittest.TestCase): self.assertEqual(Point.__slots__, ()) self.assertEqual(Point.__module__, __name__) self.assertEqual(Point.__getitem__, tuple.__getitem__) - self.assert_('__getitem__' in Point.__dict__) # superclass methods localized def test_instance(self): Point = NamedTuple('Point', 'x y') @@ -50,8 +49,10 @@ class TestNamedTuple(unittest.TestCase): def test_main(verbose=None): + import collections as CollectionsModule test_classes = [TestNamedTuple] test_support.run_unittest(*test_classes) + test_support.run_doctest(CollectionsModule, verbose) if __name__ == "__main__": test_main(verbose=True) |