Add registered_parameter_handlers property to ForceField

openforcefield/tests/test_forcefield.py

@@ -1211,6 +1211,26 @@ def test_nonbonded_method_resolution(self,
                 forcefield.get_parameter_handler('Electrostatics', {}).method = electrostatics_method
                 omm_system = forcefield.create_openmm_system(topology)
 
+    def test_registered_parameter_handlers(self):
+        """Test registered_parameter_handlers property"""
+        forcefield = ForceField('test_forcefields/smirnoff99Frosst.offxml')
+        registered_handlers = forcefield.registered_parameter_handlers
+
+        expected_handlers = [
+            'Bonds',
+            'Angles',
+            'ProperTorsions',
+            'ImproperTorsions',
+            'vdW',
+            'Electrostatics',
+            'ToolkitAM1BCC',
+        ]
+
+        for expected_handler in expected_handlers:
+            assert expected_handler in registered_handlers
+
+        assert 'LibraryChrages' not in registered_handlers
+
     def test_parameter_handler_lookup(self):
         """Ensure __getitem__ lookups work"""
         forcefield = ForceField('test_forcefields/smirnoff99Frosst.offxml')

openforcefield/typing/engines/smirnoff/forcefield.py

@@ -556,6 +556,19 @@ def register_parameter_io_handler(self, parameter_io_handler):
                     self._parameter_io_handlers[io_format]))
         self._parameter_io_handlers[io_format] = parameter_io_handler
 
+    @property
+    def registered_parameter_handlers(self):
+        """
+        Return the list of registered parameter handlers by name
+
+        .. warning :: This API is experimental and subject to change.
+
+        Returns
+        -------
+            registered_parameter_handlers: iterable of names of ParameterHandler objects in this ForceField
+
+        """
+        return [*self._parameter_handlers.keys()]
 
     # TODO: Do we want to make this optional?