py/objmodule: Factor common code for calling __init__ on builtin module.

py/builtinimport.c

@@ -389,19 +389,7 @@ mp_obj_t mp_builtin___import__(size_t n_args, const mp_obj_t *args) {
                     }
                     // found weak linked module
                     module_obj = el->value;
-                    if (MICROPY_MODULE_BUILTIN_INIT) {
-                        // look for __init__ and call it if it exists
-                        // Note: this code doesn't work fully correctly because it allows the
-                        // __init__ function to be called twice if the module is imported by its
-                        // non-weak-link name.  Also, this code is duplicated in objmodule.c.
-                        mp_obj_t dest[2];
-                        mp_load_method_maybe(el->value, MP_QSTR___init__, dest);
-                        if (dest[0] != MP_OBJ_NULL) {
-                            mp_call_method_n_kw(0, 0, dest);
-                            // register module so __init__ is not called again
-                            mp_module_register(mod_name, el->value);
-                        }
-                    }
+                    mp_module_call_init(mod_name, module_obj);
                 } else {
                     no_exist:
                 #else

py/objmodule.c

@@ -247,17 +247,7 @@ mp_obj_t mp_module_get(qstr module_name) {
         if (el == NULL) {
             return MP_OBJ_NULL;
         }
-
-        if (MICROPY_MODULE_BUILTIN_INIT) {
-            // look for __init__ and call it if it exists
-            mp_obj_t dest[2];
-            mp_load_method_maybe(el->value, MP_QSTR___init__, dest);
-            if (dest[0] != MP_OBJ_NULL) {
-                mp_call_method_n_kw(0, 0, dest);
-                // register module so __init__ is not called again
-                mp_module_register(module_name, el->value);
-            }
-        }
+        mp_module_call_init(module_name, el->value);
     }
 
     // module found, return it
@@ -268,3 +258,19 @@ void mp_module_register(qstr qst, mp_obj_t module) {
     mp_map_t *mp_loaded_modules_map = &MP_STATE_VM(mp_loaded_modules_dict).map;
     mp_map_lookup(mp_loaded_modules_map, MP_OBJ_NEW_QSTR(qst), MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)->value = module;
 }
+
+#if MICROPY_MODULE_BUILTIN_INIT
+void mp_module_call_init(qstr module_name, mp_obj_t module_obj) {
+    // Look for __init__ and call it if it exists
+    mp_obj_t dest[2];
+    mp_load_method_maybe(module_obj, MP_QSTR___init__, dest);
+    if (dest[0] != MP_OBJ_NULL) {
+        mp_call_method_n_kw(0, 0, dest);
+        // Register module so __init__ is not called again.
+        // If a module can be referenced by more than one name (eg due to weak links)
+        // then __init__ will still be called for each distinct import, and it's then
+        // up to the particular module to make sure it's __init__ code only runs once.
+        mp_module_register(module_name, module_obj);
+    }
+}
+#endif

py/objmodule.h

@@ -34,4 +34,13 @@ extern const mp_map_t mp_builtin_module_weak_links_map;
 mp_obj_t mp_module_get(qstr module_name);
 void mp_module_register(qstr qstr, mp_obj_t module);
 
+#if MICROPY_MODULE_BUILTIN_INIT
+void mp_module_call_init(qstr module_name, mp_obj_t module_obj);
+#else
+static inline void mp_module_call_init(qstr module_name, mp_obj_t module_obj) {
+    (void)module_name;
+    (void)module_obj;
+}
+#endif
+
 #endif // MICROPY_INCLUDED_PY_OBJMODULE_H