typeobject

Typeobject refers to the runtime representation of a type or class in Python. In Python's object model, every class or type is an instance of a metaclass, and the default metaclass is type. The built-in type object named type is at the root of the type hierarchy and governs core behavior of types and their instances.

Each type object describes a type's name, bases, method resolution order, and the set of attributes and behaviors it implements. In CPython the type object is implemented as the C struct PyTypeObject with numerous slots that describe how the type is allocated, deallocated, and how its instances are created, initialized, compared, and interacted with. The type's behavior is expressed through these slots, such as tp_new, tp_init, tp_call, and tp_getattro.

Type objects are used at runtime to query and manipulate types. The type() function has two roles: it returns the type of an object, and it can create new types when given a name, bases, and dict. For example, type('MyClass', (Base,), {'attr': 1}) creates a new class. Classes expose metadata like __name__, __bases__, and __dict__, and participate in the MRO. The metaclass system centers on type: by default, classes are instances of type, and a metaclass can customize class creation by deriving from type or by declaring a different metaclass.

Significance: Type objects are central to Python's dynamic nature, enabling introspection, dynamic class creation, and metaprogramming. They underpin core mechanisms such as class construction, the descriptor protocol, and the overall type hierarchy.