Add extension property to views and added LABTHINGS_EXTENSIONS class list loader

Author: Joel Collins

src/labthings/extensions.py

@@ -109,6 +109,9 @@ def add_view(self, view_class, *urls, endpoint=None, **kwargs):
         for url in cleaned_urls:
             self._rules[url] = self._views[endpoint]
 
+        # Store this extension name as the View owner
+        view_class._parent_extension_name = self.name
+
     def on_register(self, function, args=None, kwargs=None):
         """
 
@@ -262,11 +265,12 @@ def find_extensions_in_file(extension_path: str, module_name="extensions") -> li
         )
         return []
     else:
+        # TODO: Add documentation links to warnings
         if hasattr(mod, "LABTHINGS_EXTENSIONS"):
             return [
-                ext_obj
-                for ext_obj in getattr(mod, "LABTHINGS_EXTENSIONS")
-                if isinstance(ext_obj, BaseExtension)
+                ext_class()
+                for ext_class in getattr(mod, "LABTHINGS_EXTENSIONS")
+                if issubclass(ext_class, BaseExtension)
             ]
         elif hasattr(mod, "__extensions__"):
             logging.warning(

src/labthings/views/__init__.py

@@ -8,7 +8,7 @@
 
 from ..actions.pool import Pool
 from ..deque import Deque
-from ..find import current_labthing
+from ..find import current_labthing, find_extension
 from ..marshalling import marshal_with, use_args
 from ..representations import DEFAULT_REPRESENTATIONS
 from ..schema import ActionSchema, EventSchema, Schema, build_action_schema
@@ -40,6 +40,11 @@ class View(MethodView):
     _cls_tags: Set[str] = set()  # Class tags that shouldn't be removed
     _opmap: Dict[str, str] = {}  # Mapping of Thing Description ops to class methods
 
+    # Name of parent extension, if one exists.
+    # This is only used for extension development where Views are added to the extension.
+    # We store the name instead of the object itself to prevent circular references.
+    _parent_extension_name: Optional[str] = None
+
     def __init__(self, *args, **kwargs):
         MethodView.__init__(self, *args, **kwargs)
 
@@ -50,6 +55,12 @@ def __init__(self, *args, **kwargs):
             else DEFAULT_REPRESENTATIONS
         )
 
+    @property
+    def extension(self):
+        if self._parent_extension_name:
+            return find_extension(self._parent_extension_name)
+        return None
+
     @classmethod
     def get_tags(cls):
         """ """
@@ -257,7 +268,7 @@ class EventView(View):
 
     # Internal
     _opmap = {
-        "subscribeevent": "get",
+        "subscribeevent": "get"
     }  # Mapping of Thing Description ops to class methods
     _cls_tags = {"events"}
     _deque = Deque()  # Action queue