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PyAPI: Refactor attribute access to avoid creating & clearing exceptions

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- Add PyObject_GetOptionalAttrString (only available in Python 3.13).
- When registering RNA classes use optional attribute access to avoid
  raising and clearing exceptions.
- Refactor macro that handles substituting Python's built-ins
  with a `for` loop for better readability.
This commit is contained in:
Campbell Barton
2025-07-04 02:08:57 +00:00
parent dad8bddd78
commit 2a414eea0c
2 changed files with 102 additions and 63 deletions
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13
source/blender/python/generic/python_compat.hh
View File

@@ -28,6 +28,19 @@
#if PY_VERSION_HEX < 0x030d0000
# define PyObject_GetOptionalAttr _PyObject_LookupAttr
[[nodiscard]] Py_LOCAL_INLINE(int)
PyObject_GetOptionalAttrString(PyObject *obj, const char *name, PyObject **result)
{
PyObject *oname = PyUnicode_FromString(name);
if (oname == nullptr) {
*result = nullptr;
return nullptr;
}
const int status = PyObject_GetOptionalAttr(obj, oname, result);
Py_DECREF(oname);
return status;
}
# define Py_IsFinalizing _Py_IsFinalizing
#endif

152
source/blender/python/intern/bpy_rna.cc
View File

@@ -9232,7 +9232,6 @@ static int bpy_class_validate_recursive(PointerRNA *dummy_ptr,
StructRNA *srna_base = RNA_struct_base(srna);
PyObject *py_class = (PyObject *)py_data;
PyObject *base_class = static_cast<PyObject *>(RNA_struct_py_type_get(srna));
PyObject *item;
int i, arg_count, func_arg_count, func_arg_min_count = 0;
const char *py_class_name = ((PyTypeObject *)py_class)->tp_name; /* __name__ */
@@ -9262,21 +9261,31 @@ static int bpy_class_validate_recursive(PointerRNA *dummy_ptr,
continue;
}
item = PyObject_GetAttrString(py_class, RNA_function_identifier(func));
PyObject *item;
switch (PyObject_GetOptionalAttrString(py_class, RNA_function_identifier(func), &item)) {
case 1: {
break;
}
case 0: {
if ((flag & (FUNC_REGISTER_OPTIONAL & ~FUNC_REGISTER)) == 0) {
PyErr_Format(PyExc_AttributeError,
"expected %.200s, %.200s class to have an \"%.200s\" attribute",
class_type,
py_class_name,
RNA_function_identifier(func));
return -1;
}
break;
}
case -1: { /* Unexpected error, an exception will have been raise. */
return -1;
}
}
have_function[i] = (item != nullptr);
i++;
if (item == nullptr) {
if ((flag & (FUNC_REGISTER_OPTIONAL & ~FUNC_REGISTER)) == 0) {
PyErr_Format(PyExc_AttributeError,
"expected %.200s, %.200s class to have an \"%.200s\" attribute",
class_type,
py_class_name,
RNA_function_identifier(func));
return -1;
}
PyErr_Clear();
continue;
}
@@ -9360,10 +9369,18 @@ static int bpy_class_validate_recursive(PointerRNA *dummy_ptr,
Py_DECREF(item_orig);
}
/* Allow Python `__name__` to be used for `bl_idname` for convenience. */
struct {
const char *rna_attr;
PyObject *py_attr;
} bpy_property_substitutions[] = {
{"bl_idname", bpy_intern_str___name__},
{"bl_description", bpy_intern_str___doc__},
};
/* Verify properties. */
lb = RNA_struct_type_properties(srna);
LISTBASE_FOREACH (Link *, link, lb) {
const char *identifier;
PropertyRNA *prop = (PropertyRNA *)link;
const int flag = RNA_property_flag(prop);
@@ -9371,58 +9388,67 @@ static int bpy_class_validate_recursive(PointerRNA *dummy_ptr,
continue;
}
/* TODO(@ideasman42): Use #PyObject_GetOptionalAttr(), also in the macro below. */
identifier = RNA_property_identifier(prop);
item = PyObject_GetAttrString(py_class, identifier);
if (item == nullptr) {
PyErr_Clear();
/* Sneaky workaround to use the class name as the bl_idname. */
#define BPY_REPLACEMENT_STRING(rna_attr, py_attr) \
else if (STREQ(identifier, rna_attr)) { \
if ((item = PyObject_GetAttr(py_class, py_attr))) { \
if (item != Py_None) { \
if (pyrna_py_to_prop(dummy_ptr, prop, nullptr, item, "validating class:") != 0) { \
Py_DECREF(item); \
return -1; \
} \
Py_DECREF(item); \
} \
else { \
Py_DECREF(item); \
item = nullptr; \
} \
} \
else { \
PyErr_Clear(); \
} \
} /* Intentionally allow else here. */
if (false) {
} /* Needed for macro. */
BPY_REPLACEMENT_STRING("bl_idname", bpy_intern_str___name__)
BPY_REPLACEMENT_STRING("bl_description", bpy_intern_str___doc__)
#undef BPY_REPLACEMENT_STRING
if (item == nullptr && ((flag & PROP_REGISTER_OPTIONAL) != PROP_REGISTER_OPTIONAL)) {
PyErr_Format(PyExc_AttributeError,
"expected %.200s, %.200s class to have an \"%.200s\" attribute",
class_type,
py_class_name,
identifier);
return -1;
}
PyErr_Clear();
}
else {
if (pyrna_py_to_prop(dummy_ptr, prop, nullptr, item, "validating class:") != 0) {
const char *identifier = RNA_property_identifier(prop);
PyObject *item = nullptr;
switch (PyObject_GetOptionalAttrString(py_class, identifier, &item)) {
case 1: { /* Found. */
if (pyrna_py_to_prop(dummy_ptr, prop, nullptr, item, "validating class:") != 0) {
Py_DECREF(item);
return -1;
}
Py_DECREF(item);
return -1;
break;
}
case -1: { /* Not found (an unexpected error). */
/* Typically the attribute will exist or not, in previous releases all errors
* were assumed to be missing attributes, so print the error and move on. */
PyErr_Print();
[[fallthrough]];
}
case 0: { /* Not found, check for fallbacks. */
/* Sneaky workaround to use the class name as the `bl_idname`. */
int i;
for (i = 0; i < ARRAY_SIZE(bpy_property_substitutions); i += 1) {
if (STREQ(identifier, bpy_property_substitutions[i].rna_attr)) {
break;
}
}
if (i < ARRAY_SIZE(bpy_property_substitutions)) {
PyObject *py_attr = bpy_property_substitutions[i].py_attr;
switch (PyObject_GetOptionalAttr(py_class, py_attr, &item)) {
case 1: { /* Found. */
if (UNLIKELY(item == Py_None)) {
Py_DECREF(item);
item = nullptr;
}
else {
if (pyrna_py_to_prop(dummy_ptr, prop, nullptr, item, "validating class:") != 0) {
Py_DECREF(item);
return -1;
}
Py_DECREF(item);
}
break;
}
case -1: { /* Not found (an unexpected error). */
PyErr_Print();
break;
}
}
}
if (item == nullptr && ((flag & PROP_REGISTER_OPTIONAL) != PROP_REGISTER_OPTIONAL)) {
PyErr_Format(PyExc_AttributeError,
"expected %.200s, %.200s class to have an \"%.200s\" attribute",
class_type,
py_class_name,
identifier);
return -1;
}
break;
}
Py_DECREF(item);
}
}