Merge pull request #162 from labthings/new-extension-manifest

New extension manifest

Author: jtc42

src/labthings/extensions.py

@@ -3,12 +3,14 @@
 import os
 import sys
 import traceback
+import inspect
 from importlib import util
 from typing import Callable, Dict, List, Union
 
 from flask import url_for
 
 from .utilities import camel_to_snake, get_docstring, snake_to_spine
+from .views import View as BaseView
 from .views.builder import static_from
 
 
@@ -109,6 +111,10 @@ 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
+        if issubclass(view_class, BaseView):
+            view_class.set_extension(self.name)
+
     def on_register(self, function, args=None, kwargs=None):
         """
 
@@ -262,11 +268,37 @@ def find_extensions_in_file(extension_path: str, module_name="extensions") -> li
         )
         return []
     else:
-        if hasattr(mod, "__extensions__"):
+        # TODO: Add documentation links to warnings
+        if hasattr(mod, "LABTHINGS_EXTENSIONS"):
+            ext_objects = []
+            for ext_element in getattr(mod, "LABTHINGS_EXTENSIONS"):
+                if inspect.isclass(ext_element) and issubclass(
+                    ext_element, BaseExtension
+                ):
+                    ext_objects.append(ext_element())
+                elif isinstance(ext_element, BaseExtension):
+                    logging.warning(
+                        "%s: Extension instance passed instead of class. LABTHINGS_EXTENSIONS should contain classes, not instances.",
+                        ext_element,
+                    )
+                    ext_objects.append(ext_element)
+                else:
+                    logging.error(
+                        "Unsupported extension type %s. Skipping.", type(ext_element)
+                    )
+            return ext_objects
+        elif hasattr(mod, "__extensions__"):
+            logging.warning(
+                "Explicit extension list using the __extensions__ global is deprecated. Please use LABTHINGS_EXTENSIONS instead."
+            )
             return [
                 getattr(mod, ext_name) for ext_name in getattr(mod, "__extensions__")
             ]
         else:
+            logging.warning(
+                "No LTX_MANIFEST found for %s. Searching for implicit extension objects.",
+                extension_path,
+            )
             return find_instances_in_module(mod, BaseExtension)
 
 

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 +55,16 @@ 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 set_extension(cls, extension_name: str):
+        cls._parent_extension_name = extension_name
+
     @classmethod
     def get_tags(cls):
         """ """
@@ -257,7 +272,7 @@ class EventView(View):
 
     # Internal
     _opmap = {
-        "subscribeevent": "get",
+        "subscribeevent": "get"
     }  # Mapping of Thing Description ops to class methods
     _cls_tags = {"events"}
     _deque = Deque()  # Action queue