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Diffstat (limited to 'Doc/c-api/gcsupport.rst')
| -rw-r--r-- | Doc/c-api/gcsupport.rst | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/Doc/c-api/gcsupport.rst b/Doc/c-api/gcsupport.rst index 55ed9d4..338365b 100644 --- a/Doc/c-api/gcsupport.rst +++ b/Doc/c-api/gcsupport.rst @@ -33,6 +33,17 @@ Constructors for container types must conform to two rules: #. Once all the fields which may contain references to other containers are initialized, it must call :c:func:`PyObject_GC_Track`. + .. warning:: + If a type adds the Py_TPFLAGS_HAVE_GC, then it *must* implement at least + a :c:member:`~PyTypeObject.tp_traverse` handler or explicitly use one + from its subclass or subclasses. + + Some APIs like :c:func:`PyType_FromSpecWithBases` or + :c:func:`PyType_FromSpec` will automatically populate the + :c:member:`~PyTypeObject.tp_flags`, :c:member:`~PyTypeObject.tp_traverse` + and :c:member:`~PyTypeObject.tp_clear` fields if the type inherits from a + class that implements the garbage collector protocol and the child class + does *not* include the :const:`Py_TPFLAGS_HAVE_GC` flag. .. c:function:: TYPE* PyObject_GC_New(TYPE, PyTypeObject *type) |