diff options
Diffstat (limited to 'Doc')
| -rw-r--r-- | Doc/c-api/typeobj.rst | 28 | ||||
| -rw-r--r-- | Doc/whatsnew/3.10.rst | 4 |
2 files changed, 29 insertions, 3 deletions
diff --git a/Doc/c-api/typeobj.rst b/Doc/c-api/typeobj.rst index 85f0262..5e731bd 100644 --- a/Doc/c-api/typeobj.rst +++ b/Doc/c-api/typeobj.rst @@ -1199,6 +1199,25 @@ and :c:type:`PyType_Type` effectively act as defaults.) .. versionadded:: 3.10 + .. data:: Py_TPFLAGS_DISALLOW_INSTANTIATION + + Disallow creating instances of the type: set + :c:member:`~PyTypeObject.tp_new` to NULL and don't create the ``__new__`` + key in the type dictionary. + + The flag must be set before creating the type, not after. For example, it + must be set before :c:func:`PyType_Ready` is called on the type. + + The flag is set automatically on :ref:`static types <static-types>` if + :c:member:`~PyTypeObject.tp_base` is NULL or ``&PyBaseObject_Type`` and + :c:member:`~PyTypeObject.tp_new` is NULL. + + **Inheritance:** + + This flag is not inherited. + + .. versionadded:: 3.10 + .. c:member:: const char* PyTypeObject.tp_doc @@ -1761,6 +1780,9 @@ and :c:type:`PyType_Type` effectively act as defaults.) in :c:member:`~PyTypeObject.tp_new`, while for mutable types, most initialization should be deferred to :c:member:`~PyTypeObject.tp_init`. + Set the :const:`Py_TPFLAGS_DISALLOW_INSTANTIATION` flag to disallow creating + instances of the type in Python. + **Inheritance:** This field is inherited by subtypes, except it is not inherited by @@ -2596,7 +2618,8 @@ A type that supports weakrefs, instance dicts, and hashing:: }; A str subclass that cannot be subclassed and cannot be called -to create instances (e.g. uses a separate factory func):: +to create instances (e.g. uses a separate factory func) using +:c:data:`Py_TPFLAGS_DISALLOW_INSTANTIATION` flag:: typedef struct { PyUnicodeObject raw; @@ -2609,8 +2632,7 @@ to create instances (e.g. uses a separate factory func):: .tp_basicsize = sizeof(MyStr), .tp_base = NULL, // set to &PyUnicode_Type in module init .tp_doc = "my custom str", - .tp_flags = Py_TPFLAGS_DEFAULT, - .tp_new = NULL, + .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_DISALLOW_INSTANTIATION, .tp_repr = (reprfunc)myobj_repr, }; diff --git a/Doc/whatsnew/3.10.rst b/Doc/whatsnew/3.10.rst index 2580a03..1a39066 100644 --- a/Doc/whatsnew/3.10.rst +++ b/Doc/whatsnew/3.10.rst @@ -1708,6 +1708,10 @@ New Features These functions allow to activate, deactivate and query the state of the garbage collector from C code without having to import the :mod:`gc` module. +* Add a new :c:data:`Py_TPFLAGS_DISALLOW_INSTANTIATION` type flag to disallow + creating type instances. + (Contributed by Victor Stinner in :issue:`43916`.) + Porting to Python 3.10 ---------------------- |