type, object hierarchy?

[7stud]

On Feb 4, 12:49 am, Hrvoje Niksic <hnik... at xemacs.org> wrote:
> 7stud <bbxx789_0... at yahoo.com> writes:
> > --output:--
> > (<class '__main__.Dog'>, <class '__main__.Mammals'>, <type 'object'>)
>
> > The output suggests that Dog actually is a subclass of type--despite
> > the fact that issubclass(Dog, type) returns False.
>
> What was it in the output that gave you the impression that Dog is a
> subclass of type?
>

The fact that Dog.__mro__ produces any output at all--instead of
producing an error.  object does not have an __mro__attribute, so
where did Dog inherit that attribute from?  The output of dir(type)
shoes that type has an __mro__ attribute.  Some of the evidence
suggests this might be the hierarchy:

object ---> type
 |
 V
Mammal
 |
 V
Dog


But since Dog seems to inherit __mro__ from type, that hierarchy does
not appear to be correct.  Rather this hierarchy seems more likely:


object
 |
 V
type
 |
 V
Mammal
 |
 V
Dog



> And if you want to really blow your mind,
>
> print isinstance(type, object)  # True
> print isinstance(object, type)  # True
>

Yep, I investigated that before I posted.  It doesn't seem to fit with
the latter hierarchy.