# http://code.activestate.com/recipes/500261/

from operator import itemgetter 
import sys 

def __from_iterable__(cls,arg):
    return cls.__new__(cls,*arg)


def NamedTuple(typename, field_names):
    if isinstance(field_names, str):
        field_names = field_names.split()
    nargs = len(field_names)

    def __new__(cls, *args, **kwds):
        if (len(args) == 1) and (getattr(args[0], '__iter__', False)):
            args = tuple(name for name in args[0])
        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__'],
             __field_names__ = tuple(field_names),
             __from_iterable__=classmethod(__from_iterable__),
             )
    m.update((name, property(itemgetter(index))) for index, name in enumerate(field_names))

    return type(typename, (tuple,), m)