add a public API to register data types dynamically (#532)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

dpdata/system.py

@@ -954,6 +954,17 @@ def pick_by_amber_mask(self, param, maskstr, pass_coords=False, nopbc=None):
             idx = pick_by_amber_mask(parm, maskstr)
             return self.pick_atom_idx(idx, nopbc=nopbc)
 
+    @classmethod
+    def register_data_type(cls, *data_type: Tuple[DataType]):
+        """Register data type.
+
+        Parameters
+        ----------
+        *data_type : tuple[DataType]
+            data type to be regiestered
+        """
+        cls.DTYPES = cls.DTYPES + tuple(data_type)
+
 
 def get_cell_perturb_matrix(cell_pert_fraction):
     if cell_pert_fraction < 0:
@@ -1599,9 +1610,9 @@ def to_format(self, *args, **kwargs):
         setattr(MultiSystems, method, get_func(formatcls))
 
     # at this point, System.DTYPES and LabeledSystem.DTYPES has been initialized
-    System.DTYPES = System.DTYPES + get_data_types(labeled=False)
-    LabeledSystem.DTYPES = LabeledSystem.DTYPES + get_data_types(labeled=False)
-    LabeledSystem.DTYPES = LabeledSystem.DTYPES + get_data_types(labeled=True)
+    System.register_data_type(*get_data_types(labeled=False))
+    LabeledSystem.register_data_type(*get_data_types(labeled=False))
+    LabeledSystem.register_data_type(*get_data_types(labeled=True))
 
 
 add_format_methods()