source/blender/blenkernel/BKE_callbacks.h

@@ -83,8 +83,10 @@ typedef enum {
   BKE_CB_EVT_RENDER_CANCEL,
   BKE_CB_EVT_LOAD_PRE,
   BKE_CB_EVT_LOAD_POST,
+  BKE_CB_EVT_LOAD_POST_FAIL,
   BKE_CB_EVT_SAVE_PRE,
   BKE_CB_EVT_SAVE_POST,
+  BKE_CB_EVT_SAVE_POST_FAIL,
   BKE_CB_EVT_UNDO_PRE,
   BKE_CB_EVT_UNDO_POST,
   BKE_CB_EVT_REDO_PRE,
@@ -123,6 +125,7 @@ void BKE_callback_exec_id_depsgraph(struct Main *bmain,
                                     struct ID *id,
                                     struct Depsgraph *depsgraph,
                                     eCbEvent evt);
+void BKE_callback_exec_string(struct Main *bmain, eCbEvent evt, const char *str);
 void BKE_callback_add(bCallbackFuncStore *funcstore, eCbEvent evt);
 void BKE_callback_remove(bCallbackFuncStore *funcstore, eCbEvent evt);
 

source/blender/blenkernel/intern/callbacks.c

@@ -69,6 +69,18 @@ void BKE_callback_exec_id_depsgraph(struct Main *bmain,
   BKE_callback_exec(bmain, pointers, 2, evt);
 }
 
+void BKE_callback_exec_string(struct Main *bmain, eCbEvent evt, const char *str)
+{
+  PointerRNA str_ptr;
+  PrimitiveStringRNA data = {};
+  data.value = str;
+  RNA_pointer_create(NULL, &RNA_PrimitiveString, &data, &str_ptr);
+
+  PointerRNA *pointers[1] = {&str_ptr};
+
+  BKE_callback_exec(bmain, pointers, 1, evt);
+}
+
 void BKE_callback_add(bCallbackFuncStore *funcstore, eCbEvent evt)
 {
   ASSERT_CALLBACKS_INITIALIZED();

source/blender/makesrna/RNA_types.h

@@ -774,6 +774,24 @@ typedef struct ExtensionRNA {
   StructFreeFunc free;
 } ExtensionRNA;
 
+/* Primitive types. */
+
+typedef struct PrimitiveStringRNA {
+  const char *value;
+} PrimitiveStringRNA;
+
+typedef struct PrimitiveIntRNA {
+  int value;
+} PrimitiveIntRNA;
+
+typedef struct PrimitiveFloatRNA {
+  float value;
+} PrimitiveFloatRNA;
+
+typedef struct PrimitiveBooleanRNA {
+  bool value;
+} PrimitiveBooleanRNA;
+
 #ifdef __cplusplus
 }
 #endif

source/blender/makesrna/intern/rna_rna.c

@@ -2775,6 +2775,52 @@ bool rna_property_override_apply_default(Main *bmain,
 #  undef RNA_PROPERTY_GET_SINGLE
 #  undef RNA_PROPERTY_SET_SINGLE
 
+/** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name Primitive Values
+ * \{ */
+
+/* Primitive String. */
+
+static void rna_PrimitiveString_value_get(PointerRNA *ptr, char *result)
+{
+  const PrimitiveStringRNA *data = ptr->data;
+  strcpy(result, data->value ? data->value : "");
+}
+
+static int rna_PrimitiveString_value_length(PointerRNA *ptr)
+{
+  const PrimitiveStringRNA *data = ptr->data;
+  return data->value ? strlen(data->value) : 0;
+}
+
+/* Primitive Int. */
+
+static int rna_PrimitiveInt_value_get(PointerRNA *ptr)
+{
+  const PrimitiveIntRNA *data = ptr->data;
+  return data->value;
+}
+
+/* Primitive Float. */
+
+static float rna_PrimitiveFloat_value_get(PointerRNA *ptr)
+{
+  const PrimitiveFloatRNA *data = ptr->data;
+  return data->value;
+}
+
+/* Primitive Boolean. */
+
+static bool rna_PrimitiveBoolean_value_get(PointerRNA *ptr)
+{
+  const PrimitiveBooleanRNA *data = ptr->data;
+  return data->value;
+}
+
+/** \} */
+
 #else
 
 static void rna_def_struct(BlenderRNA *brna)
@@ -3367,6 +3413,40 @@ static void rna_def_pointer_property(StructRNA *srna, PropertyType type)
   RNA_def_property_ui_text(prop, "Pointer Type", "Fixed pointer type, empty if variable type");
 }
 
+static void rna_def_rna_primitive(BlenderRNA *brna)
+{
+  /* Primitive Values, use when passing #PointerRNA is used for primitive types.
+   * For the rare cases we want to pass a value as RNA which wraps a primitive data. */
+
+  StructRNA *srna;
+  PropertyRNA *prop;
+
+  srna = RNA_def_struct(brna, "PrimitiveString", NULL);
+  RNA_def_struct_ui_text(srna, "String Value", "RNA wrapped string");
+  prop = RNA_def_property(srna, "value", PROP_STRING, PROP_BYTESTRING);
+  RNA_def_property_clear_flag(prop, PROP_EDITABLE);
+  RNA_def_property_string_funcs(
+      prop, "rna_PrimitiveString_value_get", "rna_PrimitiveString_value_length", NULL);
+
+  srna = RNA_def_struct(brna, "PrimitiveInt", NULL);
+  RNA_def_struct_ui_text(srna, "Primitive Int", "RNA wrapped int");
+  prop = RNA_def_property(srna, "value", PROP_INT, PROP_NONE);
+  RNA_def_property_clear_flag(prop, PROP_EDITABLE);
+  RNA_def_property_int_funcs(prop, "rna_PrimitiveInt_value_get", NULL, NULL);
+
+  srna = RNA_def_struct(brna, "PrimitiveFloat", NULL);
+  RNA_def_struct_ui_text(srna, "Primitive Float", "RNA wrapped float");
+  prop = RNA_def_property(srna, "value", PROP_FLOAT, PROP_NONE);
+  RNA_def_property_clear_flag(prop, PROP_EDITABLE);
+  RNA_def_property_float_funcs(prop, "rna_PrimitiveFloat_value_get", NULL, NULL);
+
+  srna = RNA_def_struct(brna, "PrimitiveBoolean", NULL);
+  RNA_def_struct_ui_text(srna, "Primitive Boolean", "RNA wrapped boolean");
+  prop = RNA_def_property(srna, "value", PROP_BOOLEAN, PROP_NONE);
+  RNA_def_property_clear_flag(prop, PROP_EDITABLE);
+  RNA_def_property_boolean_funcs(prop, "rna_PrimitiveBoolean_value_get", NULL);
+}
+
 void RNA_def_rna(BlenderRNA *brna)
 {
   StructRNA *srna;
@@ -3451,6 +3531,8 @@ void RNA_def_rna(BlenderRNA *brna)
 #  endif
 
   RNA_def_property_ui_text(prop, "Structs", "");
+
+  rna_def_rna_primitive(brna);
 }
 
 #endif

source/blender/python/intern/bpy_app_handlers.c

@@ -14,7 +14,9 @@
 #include "BKE_callbacks.h"
 
 #include "RNA_access.h"
+#include "RNA_prototypes.h"
 #include "RNA_types.h"
+
 #include "bpy_app_handlers.h"
 #include "bpy_rna.h"
 
@@ -29,6 +31,13 @@ void bpy_app_generic_callback(struct Main *main,
 
 static PyTypeObject BlenderAppCbType;
 
+#define FILEPATH_SAVE_ARG \
+  "Accepts one argument: " \
+  "the file being saved, an empty string for the startup-file."
+#define FILEPATH_LOAD_ARG \
+  "Accepts one argument: " \
+  "the file being loaded, an empty string for the startup-file."
+
 /**
  * See `BKE_callbacks.h` #eCbEvent declaration for the policy on naming.
  */
@@ -50,10 +59,15 @@ static PyStructSequence_Field app_cb_info_fields[] = {
     {"render_init", "on initialization of a render job"},
     {"render_complete", "on completion of render job"},
     {"render_cancel", "on canceling a render job"},
-    {"load_pre", "on loading a new blend file (before)"},
+
-    {"load_post", "on loading a new blend file (after)"},
+    {"load_pre", "on loading a new blend file (before)." FILEPATH_LOAD_ARG},
-    {"save_pre", "on saving a blend file (before)"},
+    {"load_post", "on loading a new blend file (after). " FILEPATH_LOAD_ARG},
-    {"save_post", "on saving a blend file (after)"},
+    {"load_post_fail", "on failure to load a new blend file (after). " FILEPATH_LOAD_ARG},
+
+    {"save_pre", "on saving a blend file (before). " FILEPATH_SAVE_ARG},
+    {"save_post", "on saving a blend file (after). " FILEPATH_SAVE_ARG},
+    {"save_post_fail", "on failure to save a blend file (after). " FILEPATH_SAVE_ARG},
+
     {"undo_pre", "on loading an undo step (before)"},
     {"undo_post", "on loading an undo step (after)"},
     {"redo_pre", "on loading a redo step (before)"},
@@ -344,7 +358,8 @@ void bpy_app_generic_callback(struct Main *UNUSED(main),
 
     /* setup arguments */
     for (int i = 0; i < pointers_num; ++i) {
-      PyTuple_SET_ITEM(args_all, i, pyrna_struct_CreatePyObject(pointers[i]));
+      PyTuple_SET_ITEM(
+          args_all, i, pyrna_struct_CreatePyObject_with_primitive_support(pointers[i]));
     }
     for (int i = pointers_num; i < num_arguments; ++i) {
       PyTuple_SET_ITEM(args_all, i, Py_INCREF_RET(Py_None));
@@ -354,7 +369,8 @@ void bpy_app_generic_callback(struct Main *UNUSED(main),
       PyTuple_SET_ITEM(args_single, 0, Py_INCREF_RET(Py_None));
     }
     else {
-      PyTuple_SET_ITEM(args_single, 0, pyrna_struct_CreatePyObject(pointers[0]));
+      PyTuple_SET_ITEM(
+          args_single, 0, pyrna_struct_CreatePyObject_with_primitive_support(pointers[0]));
     }
 
     /* Iterate the list and run the callbacks

source/blender/python/intern/bpy_rna.c

@@ -7407,6 +7407,27 @@ PyObject *pyrna_struct_CreatePyObject(PointerRNA *ptr)
   return (PyObject *)pyrna;
 }
 
+PyObject *pyrna_struct_CreatePyObject_with_primitive_support(PointerRNA *ptr)
+{
+  if (ptr->type == &RNA_PrimitiveString) {
+    const PrimitiveStringRNA *data = ptr->data;
+    return PyC_UnicodeFromBytes(data->value);
+  }
+  if (ptr->type == &RNA_PrimitiveInt) {
+    const PrimitiveIntRNA *data = ptr->data;
+    return PyLong_FromLong(data->value);
+  }
+  if (ptr->type == &RNA_PrimitiveFloat) {
+    const PrimitiveFloatRNA *data = ptr->data;
+    return PyFloat_FromDouble(data->value);
+  }
+  if (ptr->type == &RNA_PrimitiveBoolean) {
+    const PrimitiveBooleanRNA *data = ptr->data;
+    return PyBool_FromLong(data->value);
+  }
+  return pyrna_struct_CreatePyObject(ptr);
+}
+
 PyObject *pyrna_prop_CreatePyObject(PointerRNA *ptr, PropertyRNA *prop)
 {
   BPy_PropertyRNA *pyrna;

source/blender/python/intern/bpy_rna.h

@@ -173,6 +173,7 @@ void BPY_update_rna_module(void);
 // PyObject *BPY_rna_doc(void);
 PyObject *BPY_rna_types(void);
 
+PyObject *pyrna_struct_CreatePyObject_with_primitive_support(PointerRNA *ptr);
 PyObject *pyrna_struct_CreatePyObject(PointerRNA *ptr);
 PyObject *pyrna_prop_CreatePyObject(PointerRNA *ptr, PropertyRNA *prop);
 

source/blender/windowmanager/intern/wm_files.cc

@@ -632,10 +632,9 @@ void wm_file_read_report(bContext *C, Main *bmain)
  * \note In the case of #WM_file_read the file may fail to load.
  * Change here shouldn't cause user-visible changes in that case.
  */
-static void wm_file_read_pre(bContext *C, bool use_data, bool /*use_userdef*/)
+static void wm_file_read_pre(bool use_data, bool /*use_userdef*/)
 {
   if (use_data) {
-    BKE_callback_exec_null(CTX_data_main(C), BKE_CB_EVT_LOAD_PRE);
     BLI_timer_on_file_load();
   }
 
@@ -656,6 +655,10 @@ struct wmFileReadPost_Params {
   uint is_startup_file : 1;
   uint is_factory_startup : 1;
   uint reset_app_template : 1;
+
+  /* Used by #wm_homefile_read_post */
+  uint success : 1;
+  uint is_alloc : 1;
 };
 
 /**
@@ -747,7 +750,6 @@ static void wm_file_read_post(bContext *C, const struct wmFileReadPost_Params *p
   if (use_data) {
     /* important to do before nullptr'ing the context */
     BKE_callback_exec_null(bmain, BKE_CB_EVT_VERSION_UPDATE);
-    BKE_callback_exec_null(bmain, BKE_CB_EVT_LOAD_POST);
     if (is_factory_startup) {
       BKE_callback_exec_null(bmain, BKE_CB_EVT_LOAD_FACTORY_STARTUP_POST);
     }
@@ -944,6 +946,10 @@ bool WM_file_read(bContext *C, const char *filepath, ReportList *reports)
   const bool use_data = true;
   const bool use_userdef = false;
 
+  /* NOTE: either #BKE_CB_EVT_LOAD_POST or #BKE_CB_EVT_LOAD_POST_FAIL must run.
+   * Runs at the end of this function, don't return beforehand. */
+  BKE_callback_exec_string(CTX_data_main(C), BKE_CB_EVT_LOAD_PRE, filepath);
+
   /* so we can get the error message */
   errno = 0;
 
@@ -968,7 +974,7 @@ bool WM_file_read(bContext *C, const char *filepath, ReportList *reports)
     bf_reports.duration.whole = PIL_check_seconds_timer();
     struct BlendFileData *bfd = BKE_blendfile_read(filepath, &params, &bf_reports);
     if (bfd != nullptr) {
-      wm_file_read_pre(C, use_data, use_userdef);
+      wm_file_read_pre(use_data, use_userdef);
 
       /* Put aside screens to match with persistent windows later,
        * also exit screens and editors. */
@@ -1004,6 +1010,8 @@ bool WM_file_read(bContext *C, const char *filepath, ReportList *reports)
       read_file_post_params.is_startup_file = false;
       read_file_post_params.is_factory_startup = false;
       read_file_post_params.reset_app_template = false;
+      read_file_post_params.success = true;
+      read_file_post_params.is_alloc = false;
       wm_file_read_post(C, &read_file_post_params);
 
       bf_reports.duration.whole = PIL_check_seconds_timer() - bf_reports.duration.whole;
@@ -1048,7 +1056,11 @@ bool WM_file_read(bContext *C, const char *filepath, ReportList *reports)
 
   WM_cursor_wait(false);
 
-  BLI_assert(BKE_main_namemap_validate(CTX_data_main(C)));
+  Main *bmain = CTX_data_main(C);
+  BKE_callback_exec_string(
+      bmain, success ? BKE_CB_EVT_LOAD_POST : BKE_CB_EVT_LOAD_POST_FAIL, filepath);
+
+  BLI_assert(BKE_main_namemap_validate(bmain));
 
   return success;
 }
@@ -1178,10 +1190,16 @@ void wm_homefile_read_ex(bContext *C,
 #endif /* WITH_PYTHON */
   }
 
+  if (use_data) {
+    /* NOTE: either #BKE_CB_EVT_LOAD_POST or #BKE_CB_EVT_LOAD_POST_FAIL must run.
+     * This runs from #wm_homefile_read_post. */
+    BKE_callback_exec_string(CTX_data_main(C), BKE_CB_EVT_LOAD_PRE, "");
+  }
+
   /* For regular file loading this only runs after the file is successfully read.
    * In the case of the startup file, the in-memory startup file is used as a fallback
    * so we know this will work if all else fails. */
-  wm_file_read_pre(C, use_data, use_userdef);
+  wm_file_read_pre(use_data, use_userdef);
 
   if (use_data) {
     /* put aside screens to match with persistent windows later */
@@ -1392,10 +1410,14 @@ void wm_homefile_read_ex(bContext *C,
     params_file_read_post.is_factory_startup = is_factory_startup;
     params_file_read_post.reset_app_template = reset_app_template;
 
+    params_file_read_post.success = success;
+    params_file_read_post.is_alloc = false;
+
     if (r_params_file_read_post == nullptr) {
-      wm_file_read_post(C, &params_file_read_post);
+      wm_homefile_read_post(C, &params_file_read_post);
     }
     else {
+      params_file_read_post.is_alloc = true;
       *r_params_file_read_post = static_cast<wmFileReadPost_Params *>(
           MEM_mallocN(sizeof(wmFileReadPost_Params), __func__));
       **r_params_file_read_post = params_file_read_post;
@@ -1417,8 +1439,18 @@ void wm_homefile_read_post(struct bContext *C,
                            const struct wmFileReadPost_Params *params_file_read_post)
 {
   wm_file_read_post(C, params_file_read_post);
+
+  if (params_file_read_post->use_data) {
+    BKE_callback_exec_string(CTX_data_main(C),
+                             params_file_read_post->success ? BKE_CB_EVT_LOAD_POST :
+                                                              BKE_CB_EVT_LOAD_POST_FAIL,
+                             "");
+  }
+
+  if (params_file_read_post->is_alloc) {
     MEM_freeN((void *)params_file_read_post);
   }
+}
 
 /** \} */
 
@@ -1820,7 +1852,10 @@ static bool wm_file_write(bContext *C,
 
   /* Call pre-save callbacks before writing preview,
    * that way you can generate custom file thumbnail. */
-  BKE_callback_exec_null(bmain, BKE_CB_EVT_SAVE_PRE);
+
+  /* NOTE: either #BKE_CB_EVT_SAVE_POST or #BKE_CB_EVT_SAVE_POST_FAIL must run.
+   * Runs at the end of this function, don't return beforehand. */
+  BKE_callback_exec_string(bmain, BKE_CB_EVT_SAVE_PRE, filepath);
   ED_assets_pre_save(bmain);
 
   /* Enforce full override check/generation on file save. */
@@ -1906,8 +1941,6 @@ static bool wm_file_write(bContext *C,
       wm_history_file_update();
     }
 
-    BKE_callback_exec_null(bmain, BKE_CB_EVT_SAVE_POST);
-
     /* run this function after because the file can't be written before the blend is */
     if (ibuf_thumb) {
       IMB_thumb_delete(filepath, THB_FAIL); /* without this a failed thumb overrides */
@@ -1921,6 +1954,8 @@ static bool wm_file_write(bContext *C,
     ok = true;
   }
 
+  BKE_callback_exec_string(bmain, ok ? BKE_CB_EVT_SAVE_POST : BKE_CB_EVT_SAVE_POST_FAIL, filepath);
+
   if (ibuf_thumb) {
     IMB_freeImBuf(ibuf_thumb);
   }
@@ -2154,7 +2189,9 @@ static int wm_homefile_write_exec(bContext *C, wmOperator *op)
     return OPERATOR_CANCELLED;
   }
 
-  BKE_callback_exec_null(bmain, BKE_CB_EVT_SAVE_PRE);
+  /* NOTE: either #BKE_CB_EVT_SAVE_POST or #BKE_CB_EVT_SAVE_POST_FAIL must run.
+   * Runs at the end of this function, don't return beforehand. */
+  BKE_callback_exec_string(bmain, BKE_CB_EVT_SAVE_PRE, "");
   ED_assets_pre_save(bmain);
 
   /* check current window and close it if temp */
@@ -2181,18 +2218,18 @@ static int wm_homefile_write_exec(bContext *C, wmOperator *op)
   blend_write_params.remap_mode = BLO_WRITE_PATH_REMAP_ABSOLUTE;
   /* Don't apply any path changes to the current blend file. */
   blend_write_params.use_save_as_copy = true;
-  if (BLO_write_file(bmain, filepath, fileflags, &blend_write_params, op->reports) == 0) {
+  const bool ok = BLO_write_file(bmain, filepath, fileflags, &blend_write_params, op->reports);
-    printf("fail\n");
-    return OPERATOR_CANCELLED;
-  }
 
+  BKE_callback_exec_string(bmain, ok ? BKE_CB_EVT_SAVE_POST : BKE_CB_EVT_SAVE_POST_FAIL, "");
+
+  if (ok) {
     printf("ok\n");
     BKE_report(op->reports, RPT_INFO, "Startup file saved");
-
-  BKE_callback_exec_null(bmain, BKE_CB_EVT_SAVE_POST);
-
     return OPERATOR_FINISHED;
   }
+  printf("fail\n");
+  return OPERATOR_CANCELLED;
+}
 
 void WM_OT_save_homefile(wmOperatorType *ot)
 {