Fix bank_index Parameter Override

core/src/main/java/org/lflang/generator/python/PythonReactorGenerator.java

@@ -167,17 +167,22 @@ private static String generatePythonClassInstantiation(
     CodeBuilder code = new CodeBuilder();
     code.pr(PyUtil.reactorRef(instance) + " = _" + className + "(");
     code.indent();
-    // Always add the bank_index
-    code.pr("_bank_index = " + PyUtil.bankIndex(instance) + ",");
+    boolean hasBankIndexParameter = false;
     for (ParameterInstance param : instance.parameters) {
-      if (!param.getName().equals("bank_index")) {
-        code.pr(
-            "_"
-                + param.getName()
-                + "="
-                + PythonParameterGenerator.generatePythonInitializer(param)
-                + ",");
+      if (param.getName().equals("bank_index")) {
+        if (param.getOverride() != null) hasBankIndexParameter = true;
+        else continue; // Skip bank_index if it is not explicitly set
       }
+      code.pr(
+          "_"
+              + param.getName()
+              + "="
+              + PythonParameterGenerator.generatePythonInitializer(param)
+              + ",");
+    }
+    if (!hasBankIndexParameter) {
+      // Only add bank_index if not explicitly set
+      code.pr("_bank_index = " + PyUtil.bankIndex(instance) + ",");
     }
     code.unindent();
     code.pr(")");

test/Python/src/federated/BankIndexFed.lf

@@ -0,0 +1,28 @@
+target Python
+
+reactor FirstReactor(bank_index=0) {
+  output out
+
+  reaction(startup) -> out {=
+    print("bank_index: {:d}".format(self.bank_index))
+    out.set(self.bank_index)
+  =}
+}
+
+reactor SecondReactor {
+  input[4] inp
+
+  reaction(inp) {=
+    for i, port in enumerate(inp):
+        assert port.is_present
+        print("in[{:d}]: {:d}".format(i, port.value))
+        assert port.value == i
+    request_stop()
+  =}
+}
+
+federated reactor {
+  a = new[4] FirstReactor()
+  b = new SecondReactor()
+  a.out -> b.inp
+}

test/Python/src/federated/BankIndexOverride.lf

@@ -0,0 +1,12 @@
+target Python
+
+reactor SingleReactor(bank_index=0) {
+  reaction(startup) {=
+    print("bank_index: {:d}".format(self.bank_index))
+    assert(self.bank_index == 2)
+  =}
+}
+
+main reactor {
+  a = new SingleReactor(bank_index=2)
+}