type

Properties

>>> dir(type)
['__abstractmethods__', '__annotations__', '__base__', '__bases__', '__basicsize__', '__call__', '__class__', '__delattr__', '__dict__', '__dictoffset__', '__dir__', '__doc__', '__eq__', '__flags__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__instancecheck__', '__itemsize__', '__le__', '__lt__', '__module__', '__mro__', '__name__', '__ne__', '__new__', '__or__', '__prepare__', '__qualname__', '__reduce__', '__reduce_ex__', '__repr__', '__ror__', '__setattr__', '__sizeof__', '__str__', '__subclasscheck__', '__subclasses__', '__subclasshook__', '__text_signature__', '__weakrefoffset__', 'mro']

Definition

type is the metaclass for all new-style classes. type(obj) returns the object’s class. Calling type(name, bases, attrs) dynamically creates a new class. All built-in and user-defined classes are instances of type.

>>> type(5)
<class 'int'>
>>> isinstance(int, type)
True

Getting the type of an object

>>> type("hi")
<class 'str'>
>>> type([1, 2, 3]) is list
True

Creating classes dynamically

>>> Point = type("Point", (object,), {"x": 0, "y": 0})
>>> p = Point()
>>> p.x, p.y
(0, 0)

Metaclass hooks

• __prepare__(name, bases) — returns the initial class namespace (often a dict).
• __call__ — called when instantiating the class (constructs instances).
• __instancecheck__ / __subclasscheck__ — customize isinstance / issubclass.

Dunder methods

Dunder Method	Operation	Example (normal syntax)	Example (dunder call)
__call__	Create instance	int('5') → 5	int.__call__('5')
__instancecheck__	Used by isinstance()	isinstance(3, int)	int.__instancecheck__(3)
__subclasscheck__	Used by issubclass()	issubclass(bool, int)	int.__subclasscheck__(bool)
__prepare__	Class namespace setup	type.__prepare__('X',())	(rarely used manually)