Python：动态创建 class，同时向 initsubclass__() 提供参数

Question

如何动态创建 class 的子 class 并为其 __init_subclass__() 方法提供参数？

示例class：

class MyClass:
    def __init_subclass__(cls, my_name):
        print(f"Subclass created and my name is {my_name}")

通常我会这样实现我的子class：

class MySubclass(MyClass, my_name="Ellis"):
    pass

但是，当使用元class 动态创建MyClass 的子class 时，我如何传入my_name？通常我可以使用 type() 但它没有提供 my_name.

的选项

MyDynamicSubclass = type("MyDynamicSubclass", (MyClass,), {})

Answer 1

type does not mention that it accepts an unlimited number of keyword-only arguments, which you would supply through the keywords in a class statement. The only place this is hinted in is in the Data Model in the section Creating the class object 的基本文档：

Once the class namespace has been populated by executing the class body, the class object is created by calling metaclass(name, bases, namespace, **kwds) (the additional keywords passed here are the same as those passed to __prepare__).

通常，您不会将此功能与 type 一起使用，正是因为 __init_subclass__:

The default implementation object.__init_subclass__ does nothing, but raises an error if it is called with any arguments.

由于您已经覆盖了默认实现，您可以将动态 class 创建为

MyDynamicSubclass = type("MyDynamicSubclass", (MyClass,), {}, my_name="Ellis")

Python：动态创建 class，同时向 initsubclass__() 提供参数

Python: Dynamically create class while providing arguments to initsubclass__()

python

inheritance

metaprogramming

metaclass

python-3.x

Python：动态创建 class，同时向 __init__subclass__() 提供参数

Python: Dynamically create class while providing arguments to __init__subclass__()

python

inheritance

metaprogramming

metaclass

python-3.x

Python：动态创建 class，同时向 initsubclass__() 提供参数

Python: Dynamically create class while providing arguments to initsubclass__()