pybricks.robotics.DriveBase: Add hold() method.

This is more intuitive than calling straight(0), and it never needs to be awaited.

Author: laurensvalk

CHANGELOG.md

@@ -7,6 +7,7 @@
 ### Added
 - Added `pybricks.pupdevices.MarioHub` to control it as a peripheral. It
   cannot be used as a standalone device since it cannot ne updated.
+- Added `DriveBase.hold()` method ([support#2621]).
 
 ### Changed
 - The EV3 Color Sensor now returns `Color.NONE` instead of `None` when no color

pybricks/robotics/pb_type_drivebase.c

@@ -325,6 +325,20 @@ static mp_obj_t pb_type_DriveBase_brake(mp_obj_t self_in) {
 }
 MP_DEFINE_CONST_FUN_OBJ_1(pb_type_DriveBase_brake_obj, pb_type_DriveBase_brake);
 
+// pybricks.robotics.DriveBase.hold
+static mp_obj_t pb_type_DriveBase_hold(mp_obj_t self_in) {
+
+    // Cancel awaitables.
+    pb_type_DriveBase_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    pb_type_async_schedule_stop_iteration(self->last_awaitable);
+
+    // Stop hardware.
+    pb_assert(pbio_drivebase_stop(self->db, PBIO_CONTROL_ON_COMPLETION_HOLD));
+
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_1(pb_type_DriveBase_hold_obj, pb_type_DriveBase_hold);
+
 // pybricks.robotics.DriveBase.distance
 static mp_obj_t pb_type_DriveBase_distance(mp_obj_t self_in) {
     pb_type_DriveBase_obj_t *self = MP_OBJ_TO_PTR(self_in);
@@ -467,6 +481,7 @@ static const mp_rom_map_elem_t pb_type_DriveBase_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_drive),            MP_ROM_PTR(&pb_type_DriveBase_drive_obj)    },
     { MP_ROM_QSTR(MP_QSTR_stop),             MP_ROM_PTR(&pb_type_DriveBase_stop_obj)     },
     { MP_ROM_QSTR(MP_QSTR_brake),            MP_ROM_PTR(&pb_type_DriveBase_brake_obj)    },
+    { MP_ROM_QSTR(MP_QSTR_hold),             MP_ROM_PTR(&pb_type_DriveBase_hold_obj)     },
     { MP_ROM_QSTR(MP_QSTR_distance),         MP_ROM_PTR(&pb_type_DriveBase_distance_obj) },
     { MP_ROM_QSTR(MP_QSTR_angle),            MP_ROM_PTR(&pb_type_DriveBase_angle_obj)    },
     { MP_ROM_QSTR(MP_QSTR_done),             MP_ROM_PTR(&pb_type_DriveBase_done_obj)     },