bpo-33201: Modernize "Extension types" doc (GH-6337)

* bpo-33201: Modernize "Extension types" doc
* Split tutorial and other topics
* Some small fixes
* Address some review comments
* Rename noddy* to custom* and shoddy to sublist
* Fix markup

1 files changed, 183 insertions, 0 deletions

diff --git a/Doc/includes/custom3.c b/Doc/includes/custom3.c
new file mode 100644
index 0000000..09e8735
--- /dev/null
+++ b/Doc/includes/custom3.c
@@ -0,0 +1,183 @@
+#include <Python.h>
+#include "structmember.h"
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *first; /* first name */
+    PyObject *last;  /* last name */
+    int number;
+} CustomObject;
+
+static void
+Custom_dealloc(CustomObject *self)
+{
+    Py_XDECREF(self->first);
+    Py_XDECREF(self->last);
+    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)
+{
+    PyObject *tmp;
+    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;
+    }
+    tmp = self->first;
+    Py_INCREF(value);
+    self->first = value;
+    Py_DECREF(tmp);
+    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)
+{
+    PyObject *tmp;
+    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;
+    }
+    tmp = self->last;
+    Py_INCREF(value);
+    self->last = value;
+    Py_DECREF(tmp);
+    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 = "custom3.Custom",
+    .tp_doc = "Custom objects",
+    .tp_basicsize = sizeof(CustomObject),
+    .tp_itemsize = 0,
+    .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
+    .tp_new = Custom_new,
+    .tp_init = (initproc) Custom_init,
+    .tp_dealloc = (destructor) Custom_dealloc,
+    .tp_members = Custom_members,
+    .tp_methods = Custom_methods,
+    .tp_getset = Custom_getsetters,
+};
+
+static PyModuleDef custommodule = {
+    PyModuleDef_HEAD_INIT,
+    .m_name = "custom3",
+    .m_doc = "Example module that creates an extension type.",
+    .m_size = -1,
+};
+
+PyMODINIT_FUNC
+PyInit_custom3(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;
+}