bricks/_common/micropython: Gracefully stop on stop button.

The stop button adds the traceback to the output window which can quickly push relevant output away. It also looks like an unexpected error for new programmers.

The stop traceback is almost never needed, and if it is, the user can always press CTRL+C to see it.

Author: laurensvalk

bricks/_common/micropython.c

@@ -47,26 +47,7 @@ void pb_event_poll_hook(void) {
 
 // callback for when stop button is pressed in IDE or on hub
 void pbsys_main_stop_program(bool force_stop) {
-
-    static const mp_obj_tuple_t args = {
-        .base = { .type = &mp_type_tuple },
-        .len = 1,
-        .items = { MP_ROM_QSTR(MP_QSTR_stop_space_button_space_pressed) },
-    };
-    static mp_obj_exception_t system_exit;
-
-    // Schedule SystemExit exception.
-    system_exit.base.type = force_stop ? &mp_type_SystemAbort : &mp_type_SystemExit;
-    system_exit.traceback_alloc = 0;
-    system_exit.traceback_len = 0;
-    system_exit.traceback_data = NULL;
-    system_exit.args = (mp_obj_tuple_t *)&args;
-    MP_STATE_MAIN_THREAD(mp_pending_exception) = MP_OBJ_FROM_PTR(&system_exit);
-    #if MICROPY_ENABLE_SCHEDULER
-    if (MP_STATE_VM(sched_state) == MP_SCHED_IDLE) {
-        MP_STATE_VM(sched_state) = MP_SCHED_PENDING;
-    }
-    #endif
+    mp_sched_system_exit_or_abort(force_stop);
 }
 
 bool pbsys_main_stdin_event(uint8_t c) {
@@ -107,6 +88,19 @@ static void mp_vfs_map_minimal_new_reader(mp_reader_t *reader, mp_vfs_map_minima
     reader->close = mp_vfs_map_minimal_close;
 }
 
+// Prints the exception that ended the program.
+static void print_final_exception(mp_obj_t exc) {
+    // Handle graceful stop with button or shutdown.
+    if (mp_obj_exception_match(exc, &mp_type_SystemAbort) ||
+        mp_obj_exception_match(exc, &mp_type_SystemExit)) {
+        mp_printf(&mp_plat_print, "Stop button pressed.\n");
+        return;
+    }
+
+    // Print unhandled exception with traceback.
+    mp_obj_print_exception(&mp_plat_print, exc);
+}
+
 #if PYBRICKS_OPT_COMPILER
 static void run_repl() {
     // Reset REPL history.
@@ -120,7 +114,7 @@ static void run_repl() {
         // clear any pending exceptions (and run any callbacks).
         mp_handle_pending(false);
         // Print which exception triggered this.
-        mp_obj_print_exception(&mp_plat_print, (mp_obj_t)nlr.ret_val);
+        print_final_exception(nlr.ret_val);
     }
 }
 #endif
@@ -239,8 +233,7 @@ static void run_user_program(void) {
         mp_hal_set_interrupt_char(-1);
         mp_handle_pending(false);
 
-        // Print which exception triggered this.
-        mp_obj_print_exception(&mp_plat_print, (mp_obj_t)nlr.ret_val);
+        print_final_exception(nlr.ret_val);
 
         #if PYBRICKS_OPT_COMPILER
         // On KeyboardInterrupt, drop to REPL for debugging.

bricks/_common/mpconfigport.h

@@ -50,6 +50,7 @@
 #define MICROPY_ENABLE_SOURCE_LINE              (1)
 #define MICROPY_ERROR_REPORTING                 (MICROPY_ERROR_REPORTING_DETAILED)
 #endif
+#define MICROPY_ENABLE_SYSTEM_ABORT             (1)
 #define MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG   (0)
 #define MICROPY_PY_ASYNC_AWAIT                  (0)
 #define MICROPY_MULTIPLE_INHERITANCE            (0)