Return both nodes on replacement

pyiron_workflow/nodes/composite.py

@@ -326,7 +326,7 @@ def remove_child(self, child: Node | str) -> Node:
 
     def replace_child(
         self, owned_node: Node | str, replacement: Node | type[Node]
-    ) -> Node:
+    ) -> tuple[Node, Node]:
         """
         Replaces a node currently owned with a new node instance.
         The replacement must not belong to any other parent or have any connections.
@@ -348,7 +348,7 @@ def replace_child(
                 and simply gets instantiated.)
 
         Returns:
-            (Node): The node that got removed
+            (Node, Node): The node that got removed and the new one that replaced it.
         """
         if isinstance(owned_node, str):
             owned_node = self.children[owned_node]
@@ -367,44 +367,56 @@ def replace_child(
                 )
             if replacement.connected:
                 raise ValueError("Replacement node must not have any connections")
+            replacement_node = replacement
         elif issubclass(replacement, Node):
-            replacement = replacement(label=owned_node.label)
+            replacement_node = replacement(label=owned_node.label)
         else:
             raise TypeError(
                 f"Expected replacement node to be a node instance or node subclass, but "
                 f"got {replacement}"
             )
 
-        replacement.copy_io(owned_node)  # If the replacement is incompatible, we'll
+        replacement_node.copy_io(
+            owned_node
+        )  # If the replacement is incompatible, we'll
         # fail here before we've changed the parent at all. Since the replacement was
         # first guaranteed to be an unconnected orphan, there is not yet any permanent
         # damage
         is_starting_node = owned_node in self.starting_nodes
         # In case the replaced node interfaces with the composite's IO, catch value
         # links
         inbound_links = [
-            (sending_channel, replacement.inputs[sending_channel.value_receiver.label])
+            (
+                sending_channel,
+                replacement_node.inputs[sending_channel.value_receiver.label],
+            )
             for sending_channel in self.inputs
             if sending_channel.value_receiver in owned_node.inputs
         ]
         outbound_links = [
-            (replacement.outputs[sending_channel.label], sending_channel.value_receiver)
+            (
+                replacement_node.outputs[sending_channel.label],
+                sending_channel.value_receiver,
+            )
             for sending_channel in owned_node.outputs
             if sending_channel.value_receiver in self.outputs
         ]
         self.remove_child(owned_node)
-        replacement.label, owned_node.label = owned_node.label, replacement.label
-        self.add_child(replacement)
+        replacement_node.label, owned_node.label = (
+            owned_node.label,
+            replacement_node.label,
+        )
+        self.add_child(replacement_node)
         if is_starting_node:
-            self.starting_nodes.append(replacement)
+            self.starting_nodes.append(replacement_node)
         for sending_channel, receiving_channel in inbound_links + outbound_links:
             sending_channel.value_receiver = receiving_channel
 
         # Clear caches
         self._cached_inputs = None
-        replacement._cached_inputs = None
+        replacement_node._cached_inputs = None
 
-        return owned_node
+        return owned_node, replacement_node
 
     def executor_shutdown(self, wait=True, *, cancel_futures=False):
         """

pyiron_workflow/nodes/macro.py

@@ -219,7 +219,7 @@ class Macro(Composite, StaticNode, ScrapesIO, ABC):
         >>> # With the replace method
         >>> # (replacement target can be specified by label or instance,
         >>> # the replacing node can be specified by instance or class)
-        >>> replaced = adds_six_macro.replace_child(adds_six_macro.one, add_two())
+        >>> replaced, _ = adds_six_macro.replace_child(adds_six_macro.one, add_two())
         >>> # With the replace_with method
         >>> adds_six_macro.two.replace_with(add_two())
         >>> # And by assignment of a compatible class to an occupied node label

pyiron_workflow/workflow.py

@@ -497,8 +497,10 @@ def _owned_io_panels(self) -> list[IO]:
 
     def replace_child(
         self, owned_node: Node | str, replacement: Node | type[Node]
-    ) -> Node:
-        super().replace_child(owned_node=owned_node, replacement=replacement)
+    ) -> tuple[Node, Node]:
+        replaced, replacement_node = super().replace_child(
+            owned_node=owned_node, replacement=replacement
+        )
 
         # Finally, make sure the IO is constructible with this new node, which will
         # catch things like incompatible IO maps
@@ -509,11 +511,11 @@ def replace_child(
         except Exception as e:
             # If IO can't be successfully rebuilt using this node, revert changes and
             # raise the exception
-            self.replace_child(replacement, owned_node)  # Guaranteed to work since
+            self.replace_child(replacement_node, replaced)  # Guaranteed to work since
             # replacement in the other direction was already a success
             raise e
 
-        return owned_node
+        return replaced, replacement_node
 
     @property
     def parent(self) -> None: