Added slots abstract method

force_bdss/data_sources/base_data_source.py

@@ -37,3 +37,26 @@ class BaseDataSource(ABCHasStrictTraits):
         List(DataValue)
             A list containing the computed Data Values.
         """
+
+    @abc.abstractmethod
+    def slots(self, model):
+        """Returns the input (and output) slots of the DataSource.
+        Slots are the entities that are needed (and produced) by this
+        DataSource.
+
+        The slots may depend on the configuration options, and thus the model.
+        This allows, for example, to change the slots depending if an option
+        is enabled or not.
+
+        Parameters
+        ----------
+        model: BaseDataSourceModel
+            The model of the DataSource, instantiated through create_model()
+
+        Returns
+        -------
+        list[tuple, tuple]
+            A list containing two tuples, the first element is the input slots,
+            the second element is the output slots. Each slot must be an
+            instance of the Slot class.
+        """