Hello Daniel,
Thanks for the reply.
Everytime I use PyObject_SetAttrString(obj, attr_name, py_val) and I
don't
need the reference to py_val I should decrement the reference after this
call?
It really depends on /how/ the object is created. If the
method used to create *py_val* increases the reference count
on the object and another function any other function is
used to increase the reference count, you should use Py_DECREF
or Py_XDECREF.
So for example:
PyObject *py_val = PyInt_FromLong(5)
PyObject_SetAttrString(py_obj, "val", py_val);
Py_DECREF(py_val)
Right?
In this case is right. *PyInt_FromLong()* returns a new
reference: 'Return value: New reference.', which is increasing
the reference count and PyObject_SetAttrString does it twice,
then you have a reference count of two and you need to decrement
the initial reference counting of the object, or you will have
a memory leak.
[quote]
int PyObject_SetAttr(PyObject *o, PyObject *attr_name, PyObject *v)
Set the value of the attribute named attr_name, for object o, to the value
v. Returns -1 on failure. This is the equivalent of the Python statement
o.attr_name = v.
int PyObject_SetAttrString(PyObject *o, const char *attr_name, PyObject *v)
Set the value of the attribute named attr_name, for object o, to the value
v. Returns -1 on failure. This is the equivalent of the Python statement
o.attr_name = v.
[/quote]
Looking at the documentation, should I have understood that the passed value
reference will be incremented and that I should decrement it if I don't need
it?
Or I should have understood just because of the fact that whenever we have x
= b (be it from the C api in a form of SetAttr()) then we should know that
b's reference will be incremented. ?
Because, before this discussion I did not know I should decrease the
reference after SetAttr()
If so, take sysmodule.c:
if (PyObject_SetAttrString(builtins, "_", Py_None) != 0)
return NULL;
Shouldn't they also call Py_DECREF(Py_None) ?
No, I think that Py_None do not needs to decrease the
reference count...
None is an object like other objects. I think its reference must be taken
into consideration too, for instance why there is the convenience macro:
Py_RETURN_NONE ?
--
Elias
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