types.ClassType

We can provide a custom metaclass by setting __metaclass__ in a class definition to any callable that takes the same arguments as type.

When the Python interpreter executes a class statement […], it calls type with the following arguments:

• The name of the class as a string
• A tuple of base classes - for our example this is the ‘one-pl’ 1
• A dictionary containing members of the class (class attributes, methods, etc) mapped by their names

a descriptor is an object attribute with “binding behavior”, one whose attribute access has been overridden by methods in the descriptor protocol.

Descriptors that only define get are called non-data descriptors (they are typically used for methods but other uses are possible).

If an object defines both __get__ and __set__, it is considered a data descriptor.

overriding __getattribute__ prevents automatic descriptor calls

If an instance’s dictionary has an entry with the same name as a data descriptor, the data descriptor takes precedence. If an instance’s dictionary has an entry with the same name as a non-data descriptor, the dictionary entry takes precedence.