#define PY_SSIZE_T_CLEAN
#include <Python.h>
#include "structmember.h"

typedef struct {
 PyObject_HEAD
 PyObject *first; /* first name */
 PyObject *last; /* last name */
 int number;
} CustomObject;

static int
Custom_traverse(CustomObject *self, visitproc visit, void *arg)
{
 Py_VISIT(self->first);
 Py_VISIT(self->last);
 return 0;
}

static int
Custom_clear(CustomObject *self)
{
 Py_CLEAR(self->first);
 Py_CLEAR(self->last);
 return 0;
}

static void
Custom_dealloc(CustomObject *self)
{
 PyObject_GC_UnTrack(self);
 Custom_clear(self);
 Py_TYPE(self)->tp_free((PyObject *) self);
}

static PyObject *
Custom_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
 CustomObject *self;
 self = (CustomObject *) type->tp_alloc(type, 0);
 if (self != NULL) {
 self->first = PyUnicode_FromString("");
 if (self->first == NULL) {
 Py_DECREF(self);
 return NULL;
 }
 self->last = PyUnicode_FromString("");
 if (self->last == NULL) {
 Py_DECREF(self);
 return NULL;
 }
 self->number = 0;
 }
 return (PyObject *) self;
}

static int
Custom_init(CustomObject *self, PyObject *args, PyObject *kwds)
{
 static char *kwlist[] = {"first", "last", "number", NULL};
 PyObject *first = NULL, *last = NULL, *tmp;

 if (!PyArg_ParseTupleAndKeywords(args, kwds, "|UUi", kwlist,
 &first, &last,
 &self->number))
 return -1;

 if (first) {
 tmp = self->first;
 Py_INCREF(first);
 self->first = first;
 Py_DECREF(tmp);
 }
 if (last) {
 tmp = self->last;
 Py_INCREF(last);
 self->last = last;
 Py_DECREF(tmp);
 }
 return 0;
}

static PyMemberDef Custom_members[] = {
 {"number", T_INT, offsetof(CustomObject, number), 0,
 "custom number"},
 {NULL} /* Sentinel */
};

static PyObject *
Custom_getfirst(CustomObject *self, void *closure)
{
 Py_INCREF(self->first);
 return self->first;
}

static int
Custom_setfirst(CustomObject *self, PyObject *value, void *closure)
{
 if (value == NULL) {
 PyErr_SetString(PyExc_TypeError, "Cannot delete the first attribute");
 return -1;
 }
 if (!PyUnicode_Check(value)) {
 PyErr_SetString(PyExc_TypeError,
 "The first attribute value must be a string");
 return -1;
 }
 Py_INCREF(value);
 Py_CLEAR(self->first);
 self->first = value;
 return 0;
}

static PyObject *
Custom_getlast(CustomObject *self, void *closure)
{
 Py_INCREF(self->last);
 return self->last;
}

static int
Custom_setlast(CustomObject *self, PyObject *value, void *closure)
{
 if (value == NULL) {
 PyErr_SetString(PyExc_TypeError, "Cannot delete the last attribute");
 return -1;
 }
 if (!PyUnicode_Check(value)) {
 PyErr_SetString(PyExc_TypeError,
 "The last attribute value must be a string");
 return -1;
 }
 Py_INCREF(value);
 Py_CLEAR(self->last);
 self->last = value;
 return 0;
}

static PyGetSetDef Custom_getsetters[] = {
 {"first", (getter) Custom_getfirst, (setter) Custom_setfirst,
 "first name", NULL},
 {"last", (getter) Custom_getlast, (setter) Custom_setlast,
 "last name", NULL},
 {NULL} /* Sentinel */
};

static PyObject *
Custom_name(CustomObject *self, PyObject *Py_UNUSED(ignored))
{
 return PyUnicode_FromFormat("%S %S", self->first, self->last);
}

static PyMethodDef Custom_methods[] = {
 {"name", (PyCFunction) Custom_name, METH_NOARGS,
 "Return the name, combining the first and last name"
 },
 {NULL} /* Sentinel */
};

static PyTypeObject CustomType = {
 PyVarObject_HEAD_INIT(NULL, 0)
 .tp_name = "custom4.Custom",
 .tp_doc = "Custom objects",
 .tp_basicsize = sizeof(CustomObject),
 .tp_itemsize = 0,
 .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC,
 .tp_new = Custom_new,
 .tp_init = (initproc) Custom_init,
 .tp_dealloc = (destructor) Custom_dealloc,
 .tp_traverse = (traverseproc) Custom_traverse,
 .tp_clear = (inquiry) Custom_clear,
 .tp_members = Custom_members,
 .tp_methods = Custom_methods,
 .tp_getset = Custom_getsetters,
};

static PyModuleDef custommodule = {
 PyModuleDef_HEAD_INIT,
 .m_name = "custom4",
 .m_doc = "Example module that creates an extension type.",
 .m_size = -1,
};

PyMODINIT_FUNC
PyInit_custom4(void)
{
 PyObject *m;
 if (PyType_Ready(&CustomType) < 0)
 return NULL;

 m = PyModule_Create(&custommodule);
 if (m == NULL)
 return NULL;

 Py_INCREF(&CustomType);
 PyModule_AddObject(m, "Custom", (PyObject *) &CustomType);
 return m;
}