__repr__ for classes that use __slots__

slots_repr.py

def slots_repr(self):
    """
    Provides a readable, namedtuple-like __repr__ for classes that use __slots__.

    Usage:

    >>> class A(object):
    ...     __slots__ = ['b']
    ...     __repr__ = slots_repr
    ...
    >>> a = A()
    >>> a.b = 5
    >>> repr(a)
    "A(b=5)"
    """

    return "{class_name}({formatted_slots})".format(
        class_name=self.__class__.__name__,
        formatted_slots=', '.join(
            "{slot}={value}".format(
                slot=slot,
                value=repr(getattr(self, slot))
            )
            for slot in self.__class__.__slots__
            if getattr(self, slot, None) is not None
        )
    )