Read additional definitions from file, not hardcoded data.

You could still override the getAdditionalSettingDefinitions method like before to get the same result as previous, but you can now also just put a path in the definition_file_paths variable to load from there instead.

part of CURA-10722

UM/Settings/AdditionalSettingDefinitionAppender.py

@@ -1,7 +1,12 @@
 # Copyright (c) 2023 UltiMaker.
 # Uranium is released under the terms of the LGPLv3 or higher.
 
-from typing import Any, Dict
+import json
+from pathlib import Path
+import os.path
+from typing import Any, Dict, List
+
+from UM.Logger import Logger
 from UM.PluginObject import PluginObject
 from UM.Settings.SettingDefinition import DefinitionPropertyType, SettingDefinition
 
@@ -72,11 +77,28 @@ class AdditionalSettingDefinitionsAppender(PluginObject):
 
     def __init__(self) -> None:
         super().__init__()
+        self.definition_file_paths: List[Path] = []
 
     def getAdditionalSettingDefinitions(self) -> Dict[str, Dict[str, Any]]:
         """
-        Should return the settings added by this plugin in json format.
+        Return the settings added by this plugin in json format.
+        Put values in self.definition_file_paths if you wish to load from files, or override this function otherwise.
+
         The settings should be divided by category (either existing or new ones).
         Settings in existing categories will be appended, new categories will be created.
         """
-        raise NotImplementedError("A setting_definitions_appender needs to implement getAdditionalSettingDefinitions.")
+        result = {}
+        for path in self.definition_file_paths:
+            if not os.path.exists(path):
+                Logger.error(f"File {path} with additional settings for '{self.getId()}' doesn't exist.")
+                continue
+            try:
+                with open(path, "r", encoding = "utf-8") as definitions_file:
+                    result.update(json.load(definitions_file))
+            except OSError as oex:
+                Logger.error(f"Could not read additional settings file for '{self.getId()}' because: {str(oex)}")
+                continue
+            except json.JSONDecodeError as jex:
+                Logger.error(f"Could not parse additional settings provided by '{self.getId()}' because: {str(jex)}")
+                continue
+        return result