`list.index` supports `__start`

src/collections.cpp

@@ -258,17 +258,11 @@ namespace pkpy
                      // Return the position of x in the deque (at or after index start and before index stop). Returns the first match or raises ValueError if not found.
                      PyDeque &self = _CAST(PyDeque &, args[0]);
                      PyObject *obj = args[1];
-                     int start = 0, stop = self.dequeItems.size(); // default values
-                     if (!vm->py_eq(args[2], vm->None))
-                         start = CAST(int, args[2]);
-                     if (!vm->py_eq(args[3], vm->None))
-                         stop = CAST(int, args[3]);
+                     int start = CAST_DEFAULT(int, args[2], 0);
+                     int stop = CAST_DEFAULT(int, args[3], self.dequeItems.size());
                      int index = self.findIndex(vm, obj, start, stop);
-                     if (index != -1)
-                         return VAR(index);
-                     else
-                         vm->ValueError(_CAST(Str &, vm->py_repr(obj)) + " is not in deque");
-                     return vm->None;
+                     if (index < 0) vm->ValueError(_CAST(Str &, vm->py_repr(obj)) + " is not in deque");
+                     return VAR(index);
                  });
         // NEW: returns the index of the given object in the deque
         vm->bind(type, "__contains__(self, obj) -> bool",

src/pocketpy.cpp

@@ -803,10 +803,11 @@ void init_builtins(VM* _vm) {
         return vm->True;
     });
 
-    _vm->bind_method<1>(VM::tp_list, "index", [](VM* vm, ArgsView args) {
+    _vm->bind(_vm->_t(VM::tp_list), "index(self, value, __start=0)", [](VM* vm, ArgsView args) {
         List& self = _CAST(List&, args[0]);
         PyObject* obj = args[1];
-        for(int i=0; i<self.size(); i++){
+        int start = CAST(int, args[2]);
+        for(int i=start; i<self.size(); i++){
             if(vm->py_eq(self[i], obj)) return VAR(i);
         }
         vm->ValueError(_CAST(Str&, vm->py_repr(obj)) + " is not in list");

tests/05_list.py

@@ -116,3 +116,16 @@ assert A()[::, :2] == (slice(None, None, None), slice(None, 2, None))
 assert A()['b':'c':1, :] == (slice('b', 'c', 1), slice(None, None, None))
 assert A()[1:2, :A()[3:4, ::-1]] == (slice(1, 2, None), slice(None, (slice(3, 4, None), slice(None, None, -1)), None))
 
+a = [1, 2, 3]
+assert a.index(2) == 1
+assert a.index(1) == 0
+assert a.index(3) == 2
+
+assert a.index(2, 1) == 1
+assert a.index(1, 0) == 0
+
+try:
+    a.index(1, 1)
+    exit(1)
+except ValueError:
+    pass