type — Advanced Examples

# Every class is an instance of type
class MyClass:
    pass

print(f"type(MyClass): {type(MyClass)}")
print(f"type(type): {type(type)}")
print(f"isinstance(MyClass, type): {isinstance(MyClass, type)}")

# The class statement is syntactic sugar for type()
# class Foo(Bar): x = 1
# is equivalent to:
# Foo = type("Foo", (Bar,), {"x": 1})

# Custom metaclass inherits from type
class Meta(type):
    def __new__(mcs, name, bases, namespace):
        cls = super().__new__(mcs, name, bases, namespace)
        cls.created_by = "Meta"
        return cls

class Widget(metaclass=Meta):
    pass

print(f"type(Widget): {type(Widget)}")
print(f"Widget.created_by: {Widget.created_by}")
print(f"isinstance(Widget, Meta): {isinstance(Widget, Meta)}")