"""
record_factory: create simple classes just for holding data fields

# BEGIN RECORD_FACTORY_DEMO
    >>> Dog = record_factory('Dog', 'name weight owner')  # <1>
    >>> rex = Dog('Rex', 30, 'Bob')
    >>> rex  # <2>
    Dog(name='Rex', weight=30, owner='Bob')
    >>> name, weight, _ = rex  # <3>
    >>> name, weight
    ('Rex', 30)
    >>> "{2}'s dog weighs {1}kg".format(*rex)  # <4>
    "Bob's dog weighs 30kg"
    >>> rex.weight = 32  # <5>
    >>> rex
    Dog(name='Rex', weight=32, owner='Bob')
    >>> Dog.__mro__  # <6>
    (<class 'factories.Dog'>, <class 'object'>)

# END RECORD_FACTORY_DEMO

The factory also accepts a list or tuple of identifiers:

    >>> Dog = record_factory('Dog', ['name', 'weight', 'owner'])
    >>> Dog.__slots__
    ('name', 'weight', 'owner')

"""

# BEGIN RECORD_FACTORY
def record_factory(cls_name, field_names):
    try:
        field_names = field_names.replace(',', ' ').split()  # <1>
    except AttributeError:  # no .replace or .split
        pass  # assume it's already a sequence of identifiers
    field_names = tuple(field_names)  # <2>

    def __init__(self, *args, **kwargs):  # <3>
        attrs = dict(zip(self.__slots__, args))
        attrs.update(kwargs)
        for name, value in attrs.items():
            setattr(self, name, value)

    def __iter__(self):  # <4>
        for name in self.__slots__:
            yield getattr(self, name)

    def __repr__(self):  # <5>
        values = ', '.join('{}={!r}'.format(*i) for i
                           in zip(self.__slots__, self))
        return '{}({})'.format(self.__class__.__name__, values)

    cls_attrs = dict(__slots__ = field_names,  # <6>
                     __init__  = __init__,
                     __iter__  = __iter__,
                     __repr__  = __repr__)

    return type(cls_name, (object,), cls_attrs)  # <7>
# END RECORD_FACTORY