added option to add attributes through a method on the controller

Author: evvaaaa

src/fastcs/controller.py

@@ -12,6 +12,12 @@ def __init__(self, path: list[str] | None = None) -> None:
 
         self._bind_attrs()
 
+    @property
+    def additional_attributes(self) -> dict[str, Attribute] | None:
+        """FastCS will look for attributes on the controller, but additional attribtues
+        be provided here."""
+        return None
+
     @property
     def path(self) -> list[str]:
         """Path prefix of attributes, recursively including parent ``Controller``s."""

src/fastcs/mapping.py

@@ -54,6 +54,8 @@ def _get_single_mapping(controller: BaseController) -> SingleMapping:
             case Attribute(enabled=True):
                 attributes[attr_name] = attr
 
+    attributes.update(controller.additional_attributes or {})
+
     return SingleMapping(
         controller, scan_methods, put_methods, command_methods, attributes
     )