Reset block inputs in _assemble_graph instead of remove_connection

milanofthe · milanofthe · commit 655ed3a36066 · 2026-02-19T15:53:09.000+01:00
diff --git a/src/pathsim/simulation.py b/src/pathsim/simulation.py
@@ -446,11 +446,6 @@ def remove_connection(self, connection):
             self.logger.error(_msg)
             raise ValueError(_msg)
 
-        #zero out target input ports to avoid stale values
-        for target in connection.targets:
-            for port in target.ports:
-                target.block.inputs[port] = 0.0
-
         #remove from global connection list
         self.connections.discard(connection)
 
@@ -504,10 +499,14 @@ def remove_event(self, event):
     # system assembly -------------------------------------------------------------
 
     def _assemble_graph(self):
-        """Build the internal graph representation for fast system function 
+        """Build the internal graph representation for fast system function
         evaluation and algebraic loop resolution.
         """
 
+        #reset all block inputs to clear stale values from removed connections
+        for block in self.blocks:
+            block.inputs.reset()
+
         #time the graph construction
         with Timer(verbose=False) as T:
             self.graph = Graph(self.blocks, self.connections)
diff --git a/src/pathsim/subsystem.py b/src/pathsim/subsystem.py
@@ -337,11 +337,6 @@ def remove_connection(self, connection):
         if connection not in self.connections:
             raise ValueError(f"{connection} not part of subsystem")
 
-        #zero out target input ports to avoid stale values
-        for target in connection.targets:
-            for port in target.ports:
-                target.block.inputs[port] = 0.0
-
         self.connections.discard(connection)
 
         if self.graph:
@@ -386,6 +381,11 @@ def _assemble_graph(self):
         """Assemble internal graph of subsystem for fast
         algebraic evaluation during simulation.
         """
+
+        #reset all block inputs to clear stale values from removed connections
+        for block in self.blocks:
+            block.inputs.reset()
+
         self.graph = Graph({*self.blocks, self.interface}, self.connections)
         self._graph_dirty = False
 
diff --git a/tests/pathsim/test_simulation.py b/tests/pathsim/test_simulation.py
@@ -885,18 +885,20 @@ def test_remove_connection_error(self):
             self.Sim.remove_connection(C)
 
     def test_remove_connection_zeroes_inputs(self):
-        """Removing a connection zeroes the target block's input ports"""
+        """Removing a connection zeroes target inputs on next graph rebuild"""
         # Run a step so the connection pushes data
         self.Src.function = lambda t: 5.0
         self.Sim.step(0.01)
 
         # Int should have received input from Src
         self.assertNotEqual(self.Int.inputs[0], 0.0)
 
-        # Remove the connection
+        # Remove the connection — graph is dirty but not rebuilt yet
         self.Sim.remove_connection(self.C1)
+        self.assertTrue(self.Sim._graph_dirty)
 
-        # Target input should now be zero
+        # Next step triggers graph rebuild which resets inputs
+        self.Sim.step(0.01)
         self.assertEqual(self.Int.inputs[0], 0.0)
 
     def test_remove_event(self):
