updates data service observer

src/pydase/data_service/data_service_observer.py

@@ -1,5 +1,6 @@
 import logging
-from typing import Any
+from copy import copy
+from typing import TYPE_CHECKING, Any
 
 from pydase.data_service.state_manager import StateManager
 from pydase.observer_pattern.observable.observable import Observable
@@ -10,6 +11,10 @@ from pydase.observer_pattern.observer.property_observer import (
 )
 from pydase.utils.helpers import get_object_attr_from_path_list
 
+if TYPE_CHECKING:
+    from collections.abc import Callable
+
+
 logger = logging.getLogger(__name__)
 
 
@@ -22,6 +27,7 @@ class DataServiceObserver(Observer):
         self.property_deps_dict = reverse_dict(
             self._get_properties_and_their_dependencies(self.observable)
         )
+        self._change_callbacks: list[Callable[[str, Any, dict[str, Any]], None]] = []
         self.initialised = True
 
     def on_change(self, full_access_path: str, value: Any) -> None:
@@ -31,24 +37,38 @@ class DataServiceObserver(Observer):
         if full_access_path in self.changing_attributes:
             self.changing_attributes.remove(full_access_path)
 
-        cache_value = None
-        cache_value_dict = (
+        cached_value_dict = copy(
             self.state_manager._data_service_cache.get_value_dict_from_cache(
                 full_access_path
             )
         )
-        if cache_value_dict != {}:
-            cache_value = cache_value_dict["value"]
+
+        cached_value = cached_value_dict.get("value")
+        if cached_value != value:
+            logger.debug("'%s' changed to '%s'", full_access_path, value)
+
+        self._update_cache_value(full_access_path, cached_value_dict, value)
+
+        for callback in self._change_callbacks:
+            callback(full_access_path, value, cached_value_dict)
+
+        self._notify_dependent_property_changes(full_access_path)
+
+    def _update_cache_value(
+        self, full_access_path: str, cached_value_dict: dict[str, Any], value: Any
+    ) -> None:
+        if cached_value_dict != {}:
             self.state_manager._data_service_cache.update_cache(
                 full_access_path,
                 value,
             )
 
-        if cache_value != value:
-            logger.info("'%s' changed to '%s'", full_access_path, value)
-
-        changed_props = self.property_deps_dict.get(full_access_path, [])
+    def _notify_dependent_property_changes(self, changed_attr_path: str) -> None:
+        changed_props = self.property_deps_dict.get(changed_attr_path, [])
         for prop in changed_props:
+            # only notify about changing attribute if it is not currently being
+            # "changed" e.g. when calling the getter of a property within another
+            # property
             if prop not in self.changing_attributes:
                 self._notify_changed(
                     prop,
@@ -57,24 +77,46 @@ class DataServiceObserver(Observer):
 
     def on_change_start(self, full_access_path: str) -> None:
         self.changing_attributes.append(full_access_path)
-        # logger.info("'%s' is being changed", full_access_path)
 
     def _get_properties_and_their_dependencies(
         self, obj: Observable, prefix: str = ""
     ) -> dict[str, list[str]]:
         deps = {}
         for k, value in vars(type(obj)).items():
+            prefix = (
+                f"{prefix}." if prefix != "" and not prefix.endswith(".") else prefix
+            )
             key = f"{prefix}{k}"
             if isinstance(value, property):
                 deps[key] = get_property_dependencies(value, prefix)
 
         for k, value in vars(obj).items():
+            prefix = (
+                f"{prefix}." if prefix != "" and not prefix.endswith(".") else prefix
+            )
             key = f"{prefix}{k}"
             if isinstance(value, Observable):
-                new_prefix = f"{key}." if not key.endswith("]") else key
+                new_prefix = f"{key}."
                 deps.update(
                     self._get_properties_and_their_dependencies(value, new_prefix)
                 )
+            elif isinstance(value, list):
+                for i, item in enumerate(value):
+                    if isinstance(item, Observable):
+                        new_prefix = f"{key}[{i}]"
+                        deps.update(
+                            self._get_properties_and_their_dependencies(
+                                item, new_prefix
+                            )
+                        )
+            elif isinstance(value, dict):
+                for key, val in value.items():
+                    if isinstance(val, Observable):
+                        new_prefix = f"{key}['{key}']"
+                        deps.update(
+                            self._get_properties_and_their_dependencies(val, new_prefix)
+                        )
+
         return deps
 
     def _get_property_values(