Allow extra synapse data

spynnaker/pyNN/models/neuron/synapse_dynamics/abstract_synapse_dynamics.py

@@ -14,7 +14,7 @@
 
 from __future__ import annotations
 import logging
-from typing import Any, cast, Optional, Sequence, Tuple, TYPE_CHECKING
+from typing import Any, cast, Optional, Sequence, Tuple, Set, TYPE_CHECKING
 
 import numpy
 
@@ -226,6 +226,13 @@ def is_split_core_capable(self) -> bool:
         """
         raise NotImplementedError
 
+    def get_synapse_parameter_names(self) -> Set[str]:
+        """
+        :return: the names of the parameters that can be extracted from
+         synapses read from the machine.
+        """
+        return {"source", "target", "weight", "delay"}
+
     def get_value(self, key: str) -> Any:
         """
         Get a property.

spynnaker/pyNN/models/projection.py

@@ -341,9 +341,9 @@ def __get_data(
         fixed_values: List[Tuple[str, int]] = list()
         for attribute in attribute_names:
             data_items.append(attribute)
-            if attribute not in {"source", "target", "weight", "delay"}:
-                value = self._synapse_information.synapse_dynamics.get_value(
-                    attribute)
+            synapse_dynamics = self._synapse_information.synapse_dynamics
+            if attribute not in synapse_dynamics.get_synapse_parameter_names():
+                value = synapse_dynamics.get_value(attribute)
                 fixed_values.append((attribute, value))
 
         # Return the connection data