抱歉這個標題可能有點不太能說明我的問題

（已解決）2023.06.24 晚上更新

...原來 BeautifulSoup 有提供我想要的效果

from bs4 import BeautifulSoup, Tag

class CustomTag(Tag):
	def strict_select_one(...):
        ...

class CustomBeautifulSoup(BeautifulSoup, CustomTag):
	...

# element_classes: A dictionary mapping BeautifulSoup classes like Tag and NavigableString, to other classes you'd like to be instantiated instead as the parse tree is built. This is useful for subclassing Tag or NavigableString to modify default behavior.
soup = CustomBeautifulSoup(..., element_classes={ Tag: CustomTag })

（可是要自己解決代碼補全的問題...）

2023.06.22 晚上更新

抱歉，我以為只要將 Tag 的實例變為 CustomTag 的實例就好了。這是我的嘗試

from typing import Any

from bs4 import BeautifulSoup, Tag
import inspect

# first one is `self`
_bs4_tag_init_params = list(inspect.signature(Tag.__init__).parameters)[1:]

class CustomTag(Tag):
	@classmethod
	def _create_from_bs4_tag(cls, tag: Tag):
		custom_tag = CustomTag(**{param: getattr(tag, param) for param in _bs4_tag_init_params})
		custom_tag.extend(tag.children)
		return custom_tag

	def strict_select_one(self, selector: str, **kwargs: Any):
		if element := super().select_one(selector, **kwargs):
			return self._create_from_bs4_tag(element)
		raise TypeError(f"Element not found: '{selector}'")
        
class CustomBeautifulSoup(BeautifulSoup, CustomTag):
	...

soup = CustomBeautifulSoup("<h1><a href='1.html'>Hello World</a></h1>", "lxml")
print(soup.strict_select_one("h1").strict_select_one("a"))

以上是能運..行...但在使用 __eq__, __contains__, Tag().decompose() 等等的時候都是失敗的

我想從 Tag 擴充一些方法

from typing import Any

from bs4 import BeautifulSoup, Tag

class CustomTag(Tag):
	def strict_select_one(self, selector: str, **kwargs: Any):
		element: Tag | None = super().select_one(selector, **kwargs)
		# 返回 `element` 或 raise error

class CustomBeautifulSoup(BeautifulSoup, CustomTag):
	...

soup = CustomBeautifulSoup("<h1>123</h1>", "lxml")

因為我想用方法鏈 soup.strict_select_one(...).strict_select_one(...)
但我不知道怎麼將 Tag 的實例變為 CustomTag 的實例

（雖然直接操作 None(select_one(...).text) 的時候會引起錯誤，但主要是想學習一下）

或者除了繼承外有其他解決辦法嗎？