Message401396
Oh and obviously, it's not possible possible to define structures which *include* PyObject or PyVarObject if PyObject and PyVarObject become opaque. Example:
typedef struct {
PyObject ob_base;
Py_ssize_t ob_size; /* Number of items in variable part */
} PyVarObject;
This C code requires the PyObject structure to be fully defined (not being opaque).
A new C API and ABI where structures *don't* include PyObject or PyVarObject should be designed to allocate their members "before" the PyObject* pointer value. Something like the current PyGC_Head structure which is excluded from PyObject and stored *before* the "PyObject*" pointer.
Simplified code which allocates memory for an object implementin the GC protocol:
static PyObject *
_PyObject_GC_Malloc(size_t basicsize)
{
...
size_t size = sizeof(PyGC_Head) + basicsize;
...
PyGC_Head *g = (PyGC_Head *)PyObject_Malloc(size);
...
PyObject *op = (PyObject *)(g + 1);
return op;
} |
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Date |
User |
Action |
Args |
2021-09-08 16:14:01 | vstinner | set | recipients:
+ vstinner, nascheme, ronaldoussoren, serhiy.storchaka, steve.dower, hroncok, corona10, ZackerySpytz, pablogsal, WildCard65, BTaskaya, shihai1991, erlendaasland, kj |
2021-09-08 16:14:01 | vstinner | set | messageid: <1631117641.32.0.478239809727.issue39573@roundup.psfhosted.org> |
2021-09-08 16:14:01 | vstinner | link | issue39573 messages |
2021-09-08 16:14:01 | vstinner | create | |
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