🐛 fix import hook export

nonebot/plugin/export.py

@@ -0,0 +1,60 @@
+from contextvars import ContextVar
+
+_export: ContextVar["Export"] = ContextVar("_export")
+
+
+class Export(dict):
+    """
+    :说明:
+
+      插件导出内容以使得其他插件可以获得。
+
+    :示例:
+
+    .. code-block:: python
+
+        nonebot.export().default = "bar"
+
+        @nonebot.export()
+        def some_function():
+            pass
+
+        # this doesn't work before python 3.9
+        # use
+        # export = nonebot.export(); @export.sub
+        # instead
+        # See also PEP-614: https://www.python.org/dev/peps/pep-0614/
+        @nonebot.export().sub
+        def something_else():
+            pass
+    """
+
+    def __call__(self, func, **kwargs):
+        self[func.__name__] = func
+        self.update(kwargs)
+        return func
+
+    def __setitem__(self, key, value):
+        super().__setitem__(key,
+                            Export(value) if isinstance(value, dict) else value)
+
+    def __setattr__(self, name, value):
+        self[name] = Export(value) if isinstance(value, dict) else value
+
+    def __getattr__(self, name):
+        if name not in self:
+            self[name] = Export()
+        return self[name]
+
+
+def export() -> Export:
+    """
+    :说明:
+
+      获取插件的导出内容对象
+
+    :返回:
+
+      - ``Export``
+    """
+    return _export.get()