diff --git a/wobbl_tools/data_file.py b/wobbl_tools/data_file.py
index 6a5bc08..8c5cb61 100644
--- a/wobbl_tools/data_file.py
+++ b/wobbl_tools/data_file.py
@@ -8,13 +8,34 @@ import os
 import json
 
 
-def load_dataclass_json(dataclass, file_path: str, builtin_save: bool=True):
+def _on_attribute_change(self, key, value):
+    # call function without automatically passing "self" as argument using __func__ -
+    # and if it returns "True", set the attribute
+
+    if key == "attribute_change_event" or self.attribute_change_event.__func__(self.app, key, value):
+        self.__dict__[key] = value
+
+
+def _set_attribute_change_event(self, event):
+    self.attribute_change_event = event
+
+
+def load_dataclass_json(
+        dataclass,
+        file_path: str,
+        app: any=None,
+        builtin_save: bool=True,
+        builtin_change_event: bool=True
+):
     """
     Loads a dataclass instance from a json file.
 
     :param dataclass: The dataclass from which the instance will be created.
     :param str file_path: The path to the json file from which the data gets loaded.
+    :param app: This is necessary if you want the dataclass to execute a function on attribute change.
     :param bool builtin_save: If True, you can simply call instance.save(file_path) to store the data.
+    :param bool builtin_change_event: If True, the returned instance will call the instance.attribute_change_event
+        on the specified app.
     :return: An instance of the dataclass containing the data from the json file.
     """
 
@@ -28,9 +49,19 @@ def load_dataclass_json(dataclass, file_path: str, builtin_save: bool=True):
 
     instance = dataclass(**class_dict)
 
+    if not app is None:
+        instance.app = app
+
     if builtin_save:  # add save method so that we can easily do "instance.save()"
         dataclass.save = save_dataclass_json
 
+    if builtin_change_event:
+        if app is None:
+            raise TypeError("You need to specify the app, else this won't work.")
+
+        dataclass.set_attribute_change_event = _set_attribute_change_event
+        dataclass.__setattr__ = _on_attribute_change
+
     return instance
 
 
@@ -42,6 +73,9 @@ def save_dataclass_json(class_instance, file_path: str, indent: None | int | str
     :param None|int|str indent: The indentation level for cleaner output.
     """
 
+    if hasattr(class_instance, "app"):  # remove app because it can't and doesn't need to be stored in the file
+        del class_instance.app
+
     class_dict = class_instance.__dict__
     class_dict = dict(filter(lambda pair: not callable(pair[1]), class_dict.items()))  # filter out functions