A:

Internally, when Python creates a new object, it always uses a type and creates an instance of that object. Specifically it uses the __new__() and __init__() methods of the type (discussion of those is outside the scope of this book). In a sense, the type serves as a factory that can churn out new objects. The type of these manufactured objects will be the type object used to create them. This is why every object has a type.

A:

It looks at the base class that you specified, and uses its type as the type for the new object. In the example Example 2.4, “Creating new objects by subclassing” , <type 'type'> (the type of <type 'object'>, the specified base) is used as the type object for creating C.

A little thought reveals that under most circumstances, any subclasses of <type 'object'> (and their subclasses, and so on) will have <type 'type'> as their type.

A:

Yes. One option is by using the __metaclass__ class attribute as in the following example:

class MyCWithSpecialType(object):
    __metaclass__ = SpecialType

Now Python will create MyCWithSpecialType by instantiating SpecialType, and not <type 'type'>.

A:

No. It must be a subclass of the type of the base object. In the above example:

Implementation of something like SpecialType requires special care and is out of scope for this book.

A:

Good Question. Depends if Python can figure out which one to use. If all the bases have the same type, for example, then that will be used. If they have different types that are not related, then Python cannot figure out which type object to use. In this case specifying a __metaclass__ is required, and this __metaclass__ must be a subclass of the type of each base.

A:

Never (as long as you're asking this question anyway :)