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__all__ = ['deque', 'defaultdict', 'NamedTuple']
from _collections import deque, defaultdict
from operator import itemgetter as _itemgetter
import sys as _sys
def NamedTuple(typename, s):
"""Returns a new subclass of tuple with named fields.
>>> Point = NamedTuple('Point', 'x y')
>>> Point.__doc__ # docstring for the new class
'Point(x, y)'
>>> p = Point(11, y=22) # instantiate with positional args or keywords
>>> p[0] + p[1] # works just like the tuple (11, 22)
33
>>> x, y = p # unpacks just like a tuple
>>> x, y
(11, 22)
>>> p.x + p.y # fields also accessable by name
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>>> p # readable __repr__ with name=value style
Point(x=11, y=22)
"""
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 as 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)
if __name__ == '__main__':
# verify that instances are pickable
from cPickle import loads, dumps
Point = NamedTuple('Point', 'x y')
p = Point(x=10, y=20)
assert p == loads(dumps(p))
import doctest
TestResults = NamedTuple('TestResults', 'failed attempted')
print(TestResults(*doctest.testmod()))
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