Below python-c code which compiles properly
#include <Python.h>
#include <structmember.h>
struct rangerr {
long min;
long max;
};
//Python type to represent rangerr
struct py_rangerr {
PyObject_HEAD
struct rangerr range;
};
// * get & set methods for py_rangerr
static PyObject * py_rangerr_min_get(struct py_rangerr *self) {
self->range.min = 1;
return PyLong_FromLong(self->range.min);
}
static PyObject * py_rangerr_min_set(struct py_rangerr *self) {
printf("Setter called");
self->range.min = 1;
}
static PyObject * py_rangerr_max_get(struct py_rangerr *self) {
self->range.max = 10;
return PyLong_FromLong(self->range.max);
}
//* GetSet method definition for py_rangerr
static PyGetSetDef py_rangerr_getset[] = {
{"min",(getter)py_rangerr_min_get, (setter)py_rangerr_min_set, "min",NULL},
{"max",(getter)py_rangerr_max_get, NULL, "max",NULL},
/* Sentinel */
{NULL},
};
/******************************************************************************
*/
static void py_rangerr_dealloc(struct py_rangerr *self) {
self->ob_type->tp_free((PyObject *)self);
}
static PyTypeObject py_rangerr_type = {
PyObject_HEAD_INIT(NULL)
.tp_name = "rangerr",
.tp_basicsize = sizeof(struct py_rangerr),
.tp_dealloc = (destructor) py_rangerr_dealloc,
.tp_flags = Py_TPFLAGS_DEFAULT,
.tp_alloc = PyType_GenericAlloc,
.tp_doc = "rangerr",
.tp_getset = py_rangerr_getset,
};
void
initrangerr(void)
{
PyObject* mod;
mod = Py_InitModule3("rangerr", NULL, "An extension with a type.");
if (mod == NULL) {
return;
}
py_rangerr_type.tp_new = PyType_GenericNew;
if (PyType_Ready(&py_rangerr_type) < 0){
return;
}
Py_INCREF(&py_rangerr_type);
PyModule_AddObject(mod, "rangerr", (PyObject*)&py_rangerr_type);
}
but when I try to invoke set/get method It throws below errors:
>>> import rangerr as r
>>> r.rangerr.min
<attribute 'min' of 'rangerr' objects>
>>> r.rangerr.min=2
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: can't set attributes of built-in/extension type 'rangerr'
>>> type(r.rangerr.min)
<type 'getset_descriptor'>
Do I need add something like "PyMemberDef" ? Thanks for any pointers or help.
It's not directly possible to have a default value for arguments. You could add a function to your module to set global default values as static variables.
If you only want to initialize your instance, you should define
PyTypeObject.tp_init
likeIf you don't give values for
min
ormax
, the default values from the lineint min = 0, max = 1;
will be used.In relation to your question about the usage of
PyMemberDef
, it is, that for types likeint
it might be and less repetitive less error-prone to usePyTypeObject.tp_members
instead ofPyTypeObject.tp_getset
.Besides the typedef of setter is: