On Fri, 15 Jan 2021 09:36:11 +0100 Julien Danjou <jul...@danjou.info> wrote: > On Thu, Jan 14 2021, Tim Peters wrote: > > > I'm not clear on exactly what it is you're after, but CPython faces > > the same question all the time: _given_ a pointer to an object, is > > there, or is there not, a GC header prepended? That's answered by > > this C API function: > > > > """ > > int PyObject_IS_GC(PyObject *obj) > > > > Returns non-zero if the object implements the garbage collector > > protocol, otherwise returns 0. > > > > The object cannot be tracked by the garbage collector if this function > > returns 0. > > """ > > > > FYI, the implementation usually resolves it by looking at whether > > obj's type object has the Py_TPFLAGS_HAVE_GC flag set. > > Right, but that only works if you have the PyObject address. > If you all got is a pointer returned by PyObject_Malloc(), you don't > know if the PyObject is at this pointer address, or after the PyGC_HEAD > header that is prepended. :(
Also note that PyObject_Malloc() may also be used to allocate non-objects, for example a bytearray's payload, IIRC. Regards Antoine. _______________________________________________ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-le...@python.org https://mail.python.org/mailman3/lists/python-dev.python.org/ Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/DCXBZ6UJ5OKYCUL6MSWVQD6JT7YW5QON/ Code of Conduct: http://python.org/psf/codeofconduct/
