fix #400

include/pocketpy/interpreter/vm.h

@@ -78,6 +78,7 @@ typedef struct VM {
 
 void VM__ctor(VM* self);
 void VM__dtor(VM* self);
+int VM__index(VM* self);
 
 void VM__push_frame(VM* self, py_Frame* frame);
 void VM__pop_frame(VM* self);

include/pocketpy/pocketpy.h

@@ -90,6 +90,12 @@ typedef struct py_Callbacks {
     void (*gc_mark)(void (*f)(py_Ref val, void* ctx), void* ctx);
 } py_Callbacks;
 
+/// A struct contains the application-level callbacks.
+typedef struct py_AppCallbacks {
+    void (*on_vm_ctor)(int index);
+    void (*on_vm_dtor)(int index);
+} py_AppCallbacks;
+
 /// Native function signature.
 /// @param argc number of arguments.
 /// @param argv array of arguments. Use `py_arg(i)` macro to get the i-th argument.
@@ -125,6 +131,8 @@ PK_API void* py_getvmctx();
 PK_API void py_setvmctx(void* ctx);
 /// Setup the callbacks for the current VM.
 PK_API py_Callbacks* py_callbacks();
+/// Setup the application callbacks
+PK_API py_AppCallbacks* py_appcallbacks();
 
 /// Set `sys.argv`. Used for storing command-line arguments.
 PK_API void py_sys_setargv(int argc, char** argv);

src/interpreter/vm.c

@@ -278,9 +278,19 @@ void VM__ctor(VM* self) {
     } while(0);
 
     self->main = py_newmodule("__main__");
+
+    if(py_appcallbacks()->on_vm_ctor) {
+        int index = VM__index(self);
+        py_appcallbacks()->on_vm_ctor(index);
+    }
 }
 
 void VM__dtor(VM* self) {
+    if(py_appcallbacks()->on_vm_dtor) {
+        int index = VM__index(self);
+        py_appcallbacks()->on_vm_dtor(index);
+    }
+
     // reset traceinfo
     py_sys_settrace(NULL, true);
     LineProfiler__dtor(&self->line_profiler);

src/public/GlobalSetup.c

@@ -65,13 +65,15 @@ void py_finalize() {
     pk_names_finalize();
 }
 
-int py_currentvm() {
+int VM__index(VM* self) {
     for(int i = 0; i < 16; i++) {
-        if(pk_all_vm[i] == pk_current_vm) return i;
+        if(pk_all_vm[i] == self) return i;
     }
     return -1;
 }
 
+int py_currentvm() { return VM__index(pk_current_vm); }
+
 void py_switchvm(int index) {
     if(index < 0 || index >= 16) c11__abort("invalid vm index");
     if(!pk_all_vm[index]) {
@@ -104,6 +106,11 @@ void py_setvmctx(void* ctx) { pk_current_vm->ctx = ctx; }
 
 py_Callbacks* py_callbacks() { return &pk_current_vm->callbacks; }
 
+py_AppCallbacks* py_appcallbacks() {
+    static py_AppCallbacks _callbacks = {0};
+    return &_callbacks;
+}
+
 /////////////////////////////
 
 void py_sys_setargv(int argc, char** argv) {