diff --git a/force_bdss/data_sources/base_data_source_model.py b/force_bdss/data_sources/base_data_source_model.py
index d210f94..a5df537 100644
--- a/force_bdss/data_sources/base_data_source_model.py
+++ b/force_bdss/data_sources/base_data_source_model.py
@@ -1,4 +1,6 @@
-from traits.api import ABCHasStrictTraits, Instance, List, Event
+from traits.api import (
+    ABCHasStrictTraits, Instance, List, Event, on_trait_change
+)
 
 from force_bdss.core.input_slot_info import InputSlotInfo
 from force_bdss.core.output_slot_info import OutputSlotInfo
@@ -49,3 +51,10 @@ class BaseDataSourceModel(ABCHasStrictTraits):
             x.__getstate__() for x in self.output_slot_info
         ]
         return state
+
+    @on_trait_change("+changes_slots")
+    def _trigger_changes_slots(self, obj, name, new):
+        changes_slots = self.traits()[name].changes_slots
+
+        if changes_slots:
+            self.changes_slots = True

use traits metadata to indicate if a trait changes the slots.
Currently we require users to bind the traits that can change the slots to a handler that invokes changes_slots event. We can achieve the same by requiring a metadata entry on those traits that change the slots, and implement the binding with the event in the base class.

diff --git a/force_bdss/data_sources/tests/test_base_data_source_model.py b/force_bdss/data_sources/tests/test_base_data_source_model.py
index a9be54b..dde26ea 100644
--- a/force_bdss/data_sources/tests/test_base_data_source_model.py
+++ b/force_bdss/data_sources/tests/test_base_data_source_model.py
@@ -1,7 +1,10 @@
 import unittest
 
+from traits.api import Int
+from traits.testing.api import UnittestTools
 from force_bdss.core.input_slot_info import InputSlotInfo
 from force_bdss.core.output_slot_info import OutputSlotInfo
+from force_bdss.data_sources.base_data_source_model import BaseDataSourceModel
 from force_bdss.tests.dummy_classes.data_source import DummyDataSourceModel
 
 try:
@@ -13,9 +16,18 @@ from force_bdss.data_sources.base_data_source_factory import \
     BaseDataSourceFactory
 
 
-class TestBaseDataSourceModel(unittest.TestCase):
+class ChangesSlotsModel(BaseDataSourceModel):
+    a = Int()
+    b = Int(changes_slots=True)
+    c = Int(changes_slots=False)
+
+
+class TestBaseDataSourceModel(unittest.TestCase, UnittestTools):
+    def setUp(self):
+        self.mock_factory = mock.Mock(spec=BaseDataSourceFactory)
+
     def test_getstate(self):
-        model = DummyDataSourceModel(mock.Mock(spec=BaseDataSourceFactory))
+        model = DummyDataSourceModel(self.mock_factory)
         self.assertEqual(
             model.__getstate__(),
             {
@@ -64,3 +76,15 @@ class TestBaseDataSourceModel(unittest.TestCase):
                     }
                 ]
             })
+
+    def test_changes_slots(self):
+        model = ChangesSlotsModel(self.mock_factory)
+
+        with self.assertTraitDoesNotChange(model, "changes_slots"):
+            model.a = 5
+
+        with self.assertTraitChanges(model, "changes_slots"):
+            model.b = 5
+
+        with self.assertTraitDoesNotChange(model, "changes_slots"):
+            model.c = 5

pip install -e .
parse_log_pytest
requirements.txt
pytest pytest-cov pytest-xdist pytest-mock pytest-asyncio
3.9
requirements/base.txt
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
apptools==5.3.0
click==8.1.8
coverage==7.8.0
envisage==7.0.3
exceptiongroup==1.2.2
execnet==2.1.1
-e git+https://github.com/force-h2020/force-bdss.git@29c664514d096b9d3eb764b6167c2d77b7b129c6#egg=force_bdss
importlib_metadata==8.6.1
iniconfig==2.1.0
packaging==24.2
pbr==6.1.1
pluggy==1.5.0
pyface==8.0.0
pytest==8.3.5
pytest-asyncio==0.26.0
pytest-cov==6.0.0
pytest-mock==3.14.0
pytest-xdist==3.6.1
six==1.17.0
stevedore==5.4.1
tomli==2.2.1
traits==7.0.2
traitsui==8.0.0
typing_extensions==4.13.0
zipp==3.21.0

name: force-bdss
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - ca-certificates=2025.2.25=h06a4308_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.4.4=h6a678d5_1
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - ncurses=6.4=h6a678d5_0
  - openssl=3.0.16=h5eee18b_0
  - pip=25.0=py39h06a4308_0
  - python=3.9.21=he870216_1
  - readline=8.2=h5eee18b_0
  - setuptools=75.8.0=py39h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - tzdata=2025a=h04d1e81_0
  - wheel=0.45.1=py39h06a4308_0
  - xz=5.6.4=h5eee18b_1
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - apptools==5.3.0
      - click==8.1.8
      - coverage==7.8.0
      - envisage==7.0.3
      - exceptiongroup==1.2.2
      - execnet==2.1.1
      - importlib-metadata==8.6.1
      - iniconfig==2.1.0
      - packaging==24.2
      - pbr==6.1.1
      - pluggy==1.5.0
      - pyface==8.0.0
      - pytest==8.3.5
      - pytest-asyncio==0.26.0
      - pytest-cov==6.0.0
      - pytest-mock==3.14.0
      - pytest-xdist==3.6.1
      - six==1.17.0
      - stevedore==5.4.1
      - tomli==2.2.1
      - traits==7.0.2
      - traitsui==8.0.0
      - typing-extensions==4.13.0
      - zipp==3.21.0
prefix: /opt/conda/envs/force-bdss

force_bdss/data_sources/tests/test_base_data_source_model.py::TestBaseDataSourceModel::test_changes_slots
force_bdss/data_sources/tests/test_base_data_source_model.py::TestBaseDataSourceModel::test_getstate
force_bdss/data_sources/base_data_source_model.py
force_bdss/data_sources/base_data_source_model.py