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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)
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>>> 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()
if not ''.join([typename] + field_names).replace('_', '').isalnum():
raise ValueError('Type names and field names can only contain alphanumeric characters and underscores')
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 += '\n %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__':
# 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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