Question

According to the doc, object is all new-style classes’ base class.

And AFAIK, the so-called new-style classes are just ones which can acquire some new fetures by inheriting object, right?

I thought object inherit type or use type as its __metaclass__, but object.__bases__ gives me nothing, so where dose this object come from, and what’s relationship bewteen it and type?

Answer 1

Indeed, the type (i.e., metaclass) of object, a class, is type:

type(object) == type      # True

And since object is the base class, it has no parents of its own, as you’d expect:

object.__bases__ == ()    # True

object doesn’t have a __metaclass__ attribute because it doesn’t need one: it uses the default metaclass, type.

Now it’s a little confusing because type is in fact a subclass of object, which boggles the mind (how can type be derived from object when you need type to construct object?) but this is solved by a little hard-coding at the C level in the Python interpreter.

All this applies only to new-style classes, that is, those derived from object. In Python 3, all classes are new-style, so this applies globally in Python 3.