Cleanup: naming & reduce declaration scope in the PyAPI for lib loading

Use terms source/destination instead of from/to.

doc/python_api/examples/bpy.types.BlendDataLibraries.load.py

@@ -3,32 +3,32 @@ import bpy
 filepath = "//link_library.blend"
 
 # Load a single scene we know the name of.
-with bpy.data.libraries.load(filepath) as (data_from, data_to):
-    data_to.scenes = ["Scene"]
+with bpy.data.libraries.load(filepath) as (data_src, data_dst):
+    data_dst.scenes = ["Scene"]
 
 
 # Load all meshes.
-with bpy.data.libraries.load(filepath) as (data_from, data_to):
-    data_to.meshes = data_from.meshes
+with bpy.data.libraries.load(filepath) as (data_src, data_dst):
+    data_dst.meshes = data_src.meshes
 
 
 # Link all objects starting with "A".
-with bpy.data.libraries.load(filepath, link=True) as (data_from, data_to):
-    data_to.objects = [name for name in data_from.objects if name.startswith("A")]
+with bpy.data.libraries.load(filepath, link=True) as (data_src, data_dst):
+    data_dst.objects = [name for name in data_src.objects if name.startswith("A")]
 
 
 # Append everything.
-with bpy.data.libraries.load(filepath) as (data_from, data_to):
-    for attr in dir(data_to):
-        setattr(data_to, attr, getattr(data_from, attr))
+with bpy.data.libraries.load(filepath) as (data_src, data_dst):
+    for attr in dir(data_dst):
+        setattr(data_dst, attr, getattr(data_src, attr))
 
 
-# The loaded objects can be accessed from 'data_to' outside of the context
+# The loaded objects can be accessed from `data_dst` outside of the context
 # since loading the data replaces the strings for the data-blocks or None
 # if the data-block could not be loaded.
-with bpy.data.libraries.load(filepath) as (data_from, data_to):
-    data_to.meshes = data_from.meshes
+with bpy.data.libraries.load(filepath) as (data_src, data_dst):
+    data_dst.meshes = data_src.meshes
 # Now operate directly on the loaded data.
-for mesh in data_to.meshes:
+for mesh in data_dst.meshes:
     if mesh is not None:
         print(mesh.name)

source/blender/python/intern/bpy_library_load.cc

@@ -434,19 +434,15 @@ static PyObject *bpy_lib_load(BPy_PropertyRNA *self, PyObject *args, PyObject *k
 
 static PyObject *_bpy_names(BPy_Library *self, int blocktype)
 {
-  PyObject *list;
-  LinkNode *l, *names;
-  int totnames;
-
-  names = BLO_blendhandle_get_datablock_names(
-      self->blo_handle, blocktype, (self->flag & FILE_ASSETS_ONLY) != 0, &totnames);
-  list = PyList_New(totnames);
+  int names_num;
+  LinkNode *names = BLO_blendhandle_get_datablock_names(
+      self->blo_handle, blocktype, (self->flag & FILE_ASSETS_ONLY) != 0, &names_num);
+  PyObject *list = PyList_New(names_num);
 
   if (names) {
-    int counter = 0;
-    for (l = names; l; l = l->next) {
-      PyList_SET_ITEM(list, counter, PyUnicode_FromString((char *)l->link));
-      counter++;
+    int i = 0;
+    for (LinkNode *l = names; l; l = l->next, i++) {
+      PyList_SET_ITEM(list, i, PyUnicode_FromString((char *)l->link));
     }
     BLI_linklist_freeN(names); /* free linklist *and* each node's data */
   }
@@ -456,8 +452,6 @@ static PyObject *_bpy_names(BPy_Library *self, int blocktype)
 
 static PyObject *bpy_lib_enter(BPy_Library *self)
 {
-  PyObject *ret;
-  BPy_Library *self_from;
   ReportList *reports = &self->reports;
   BlendFileReadReport *bf_reports = &self->bf_reports;
 
@@ -474,7 +468,8 @@ static PyObject *bpy_lib_enter(BPy_Library *self)
     return nullptr;
   }
 
-  PyObject *from_dict = _PyDict_NewPresized(bpy_library_dict_num);
+  PyObject *dict_src = _PyDict_NewPresized(bpy_library_dict_num);
+  PyObject *dict_dst = self->dict; /* Only for convenience (always `self->dict`). */
   int dict_num_offset = 0;
 
   int i = 0, code;
@@ -487,60 +482,58 @@ static PyObject *bpy_lib_enter(BPy_Library *self)
     PyObject *str = PyUnicode_FromString(name_plural);
     PyObject *item;
 
-    PyDict_SetItem(self->dict, str, item = PyList_New(0));
+    PyDict_SetItem(dict_dst, str, item = PyList_New(0));
     Py_DECREF(item);
-    PyDict_SetItem(from_dict, str, item = _bpy_names(self, code));
+    PyDict_SetItem(dict_src, str, item = _bpy_names(self, code));
     Py_DECREF(item);
 
     Py_DECREF(str);
   }
 
-  /* create a dummy */
-  self_from = PyObject_New(BPy_Library, &bpy_lib_Type);
-  STRNCPY(self_from->relpath, self->relpath);
-  STRNCPY(self_from->abspath, self->abspath);
+  /* Create a dummy. */
+  BPy_Library *self_src = PyObject_New(BPy_Library, &bpy_lib_Type);
+  STRNCPY(self_src->relpath, self->relpath);
+  STRNCPY(self_src->abspath, self->abspath);
 
-  /* Library blendfile version. */
+  /* Library blend-file version. */
   {
     PyObject *version;
     PyObject *identifier = PyUnicode_FromString("version");
     blender::int3 blendfile_version;
 
-    /* From. */
+    /* Source. */
     blendfile_version = BLO_blendhandle_get_version(self->blo_handle);
     version = PyC_Tuple_PackArray_I32(&blendfile_version[0], 3);
-    PyDict_SetItem(from_dict, identifier, version);
+    PyDict_SetItem(dict_src, identifier, version);
     Py_DECREF(version);
 
-    /* To. */
+    /* Destination. */
     blendfile_version = blender::int3(
         BLENDER_FILE_VERSION / 100, BLENDER_FILE_VERSION % 100, BLENDER_FILE_SUBVERSION);
     version = PyC_Tuple_PackArray_I32(&blendfile_version[0], 3);
-    PyDict_SetItem(self->dict, identifier, version);
+    PyDict_SetItem(dict_dst, identifier, version);
     Py_DECREF(version);
 
     Py_DECREF(identifier);
   }
 
-  self_from->blo_handle = nullptr;
-  self_from->flag = 0;
-  self_from->create_liboverrides = false;
-  self_from->liboverride_flags = BKE_LIBLINK_OVERRIDE_INIT;
-  self_from->dict = from_dict; /* owns the dict */
+  self_src->blo_handle = nullptr;
+  self_src->flag = 0;
+  self_src->create_liboverrides = false;
+  self_src->liboverride_flags = BKE_LIBLINK_OVERRIDE_INIT;
+  self_src->dict = dict_src; /* owns the dict */
 
   /* While it's not a bug if the sizes differ, the size is expected to match.
    * Ensure `bpy_library_dict_num` gets updated when members are added. */
-  BLI_assert(PyDict_GET_SIZE(self_from->dict) + dict_num_offset == bpy_library_dict_num);
+  BLI_assert(PyDict_GET_SIZE(self_src->dict) + dict_num_offset == bpy_library_dict_num);
   BLI_assert(PyDict_GET_SIZE(self->dict) + dict_num_offset == bpy_library_dict_num);
   UNUSED_VARS_NDEBUG(dict_num_offset);
 
-  /* return pair */
-  ret = PyTuple_New(2);
-  PyTuple_SET_ITEMS(ret, (PyObject *)self_from, (PyObject *)self);
-  Py_INCREF(self);
-
   BKE_reports_clear(reports);
 
+  /* Return a pair. */
+  PyObject *ret = PyTuple_New(2);
+  PyTuple_SET_ITEMS(ret, (PyObject *)self_src, Py_NewRef((PyObject *)self));
   return ret;
 }