From a840806d338805fe74a9de01081d30da7605a29f Mon Sep 17 00:00:00 2001 From: Eric Snow Date: Mon, 10 Jul 2023 10:41:02 -0600 Subject: [PATCH] gh-105227: Add PyType_GetDict() (GH-105747) This compensates for static builtin types having `tp_dict` set to `NULL`. Co-authored-by: Petr Viktorin --- Doc/c-api/type.rst | 17 +++++++++++++ Doc/c-api/typeobj.rst | 14 ++++++++++- Include/cpython/object.h | 1 + ...-06-13-14-24-55.gh-issue-105227.HDL9aF.rst | 5 ++++ Modules/_testcapimodule.c | 25 +++++++++++++++++++ Objects/typeobject.c | 7 ++++++ 6 files changed, 68 insertions(+), 1 deletion(-) create mode 100644 Misc/NEWS.d/next/C API/2023-06-13-14-24-55.gh-issue-105227.HDL9aF.rst diff --git a/Doc/c-api/type.rst b/Doc/c-api/type.rst index c99c7ef93a4..a5f333e2a31 100644 --- a/Doc/c-api/type.rst +++ b/Doc/c-api/type.rst @@ -50,6 +50,23 @@ Type Objects The return type is now ``unsigned long`` rather than ``long``. +.. c:function:: PyObject* PyType_GetDict(PyTypeObject* type) + + Return the type object's internal namespace, which is otherwise only + exposed via a read-only proxy (``cls.__dict__``). This is a + replacement for accessing :c:member:`~PyTypeObject.tp_dict` directly. + The returned dictionary must be treated as read-only. + + This function is meant for specific embedding and language-binding cases, + where direct access to the dict is necessary and indirect access + (e.g. via the proxy or :c:func:`PyObject_GetAttr`) isn't adequate. + + Extension modules should continue to use ``tp_dict``, + directly or indirectly, when setting up their own types. + + .. versionadded:: 3.12 + + .. c:function:: void PyType_Modified(PyTypeObject *type) Invalidate the internal lookup cache for the type and all of its diff --git a/Doc/c-api/typeobj.rst b/Doc/c-api/typeobj.rst index 239c191457f..7249cfe79c3 100644 --- a/Doc/c-api/typeobj.rst +++ b/Doc/c-api/typeobj.rst @@ -1717,7 +1717,19 @@ and :c:type:`PyType_Type` effectively act as defaults.) called; it may also be initialized to a dictionary containing initial attributes for the type. Once :c:func:`PyType_Ready` has initialized the type, extra attributes for the type may be added to this dictionary only if they don't - correspond to overloaded operations (like :meth:`__add__`). + correspond to overloaded operations (like :meth:`__add__`). Once + initialization for the type has finished, this field should be + treated as read-only. + + Some types may not store their dictionary in this slot. + Use :c:func:`PyType_GetDict` to retreive the dictionary for an arbitrary + type. + + .. versionchanged:: 3.12 + + Internals detail: For static builtin types, this is always ``NULL``. + Instead, the dict for such types is stored on ``PyInterpreterState``. + Use :c:func:`PyType_GetDict` to get the dict for an arbitrary type. **Inheritance:** diff --git a/Include/cpython/object.h b/Include/cpython/object.h index d681435c845..ef9006431be 100644 --- a/Include/cpython/object.h +++ b/Include/cpython/object.h @@ -284,6 +284,7 @@ PyAPI_FUNC(PyTypeObject *) _PyType_CalculateMetaclass(PyTypeObject *, PyObject * PyAPI_FUNC(PyObject *) _PyType_GetDocFromInternalDoc(const char *, const char *); PyAPI_FUNC(PyObject *) _PyType_GetTextSignatureFromInternalDoc(const char *, const char *); PyAPI_FUNC(PyObject *) PyType_GetModuleByDef(PyTypeObject *, PyModuleDef *); +PyAPI_FUNC(PyObject *) PyType_GetDict(PyTypeObject *); PyAPI_FUNC(int) PyObject_Print(PyObject *, FILE *, int); PyAPI_FUNC(void) _Py_BreakPoint(void); diff --git a/Misc/NEWS.d/next/C API/2023-06-13-14-24-55.gh-issue-105227.HDL9aF.rst b/Misc/NEWS.d/next/C API/2023-06-13-14-24-55.gh-issue-105227.HDL9aF.rst new file mode 100644 index 00000000000..846663621e8 --- /dev/null +++ b/Misc/NEWS.d/next/C API/2023-06-13-14-24-55.gh-issue-105227.HDL9aF.rst @@ -0,0 +1,5 @@ +The new :c:func:`PyType_GetDict` provides the dictionary for the given type +object that is normally exposed by ``cls.__dict__``. Normally it's +sufficient to use :c:member:`~PyTypeObject.tp_dict`, but for the static +builtin types :c:member:`!tp_dict` is now always ``NULL``. :c:func:`!PyType_GetDict()` +provides the correct dict object instead. diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c index 50eaff9917f..dd2c9c72e53 100644 --- a/Modules/_testcapimodule.c +++ b/Modules/_testcapimodule.c @@ -638,6 +638,30 @@ test_get_type_qualname(PyObject *self, PyObject *Py_UNUSED(ignored)) Py_RETURN_NONE; } +static PyObject * +test_get_type_dict(PyObject *self, PyObject *Py_UNUSED(ignored)) +{ + /* Test for PyType_GetDict */ + + // Assert ints have a `to_bytes` method + PyObject *long_dict = PyType_GetDict(&PyLong_Type); + assert(long_dict); + assert(PyDict_GetItemString(long_dict, "to_bytes")); // borrowed ref + Py_DECREF(long_dict); + + // Make a new type, add an attribute to it and assert it's there + PyObject *HeapTypeNameType = PyType_FromSpec(&HeapTypeNameType_Spec); + assert(HeapTypeNameType); + assert(PyObject_SetAttrString( + HeapTypeNameType, "new_attr", Py_NewRef(Py_None)) >= 0); + PyObject *type_dict = PyType_GetDict((PyTypeObject*)HeapTypeNameType); + assert(type_dict); + assert(PyDict_GetItemString(type_dict, "new_attr")); // borrowed ref + Py_DECREF(HeapTypeNameType); + Py_DECREF(type_dict); + Py_RETURN_NONE; +} + static PyObject * pyobject_repr_from_null(PyObject *self, PyObject *Py_UNUSED(ignored)) { @@ -3472,6 +3496,7 @@ static PyMethodDef TestMethods[] = { {"test_get_statictype_slots", test_get_statictype_slots, METH_NOARGS}, {"test_get_type_name", test_get_type_name, METH_NOARGS}, {"test_get_type_qualname", test_get_type_qualname, METH_NOARGS}, + {"test_get_type_dict", test_get_type_dict, METH_NOARGS}, {"_test_thread_state", test_thread_state, METH_VARARGS}, #ifndef MS_WINDOWS {"_spawn_pthread_waiter", spawn_pthread_waiter, METH_NOARGS}, diff --git a/Objects/typeobject.c b/Objects/typeobject.c index 87519efef08..5430924e69d 100644 --- a/Objects/typeobject.c +++ b/Objects/typeobject.c @@ -237,6 +237,13 @@ _PyType_GetDict(PyTypeObject *self) return lookup_tp_dict(self); } +PyObject * +PyType_GetDict(PyTypeObject *self) +{ + PyObject *dict = lookup_tp_dict(self); + return _Py_XNewRef(dict); +} + static inline void set_tp_dict(PyTypeObject *self, PyObject *dict) {