source: python/trunk/Objects/descrobject.c@ 389

/* Descriptors -- a new, flexible way to describe attributes */

#include "Python.h"
#include "structmember.h" /* Why is this not included in Python.h? */

static void
descr_dealloc(PyDescrObject *descr)
{
        _PyObject_GC_UNTRACK(descr);
        Py_XDECREF(descr->d_type);
        Py_XDECREF(descr->d_name);
        PyObject_GC_Del(descr);
}

static char *
descr_name(PyDescrObject *descr)
{
        if (descr->d_name != NULL && PyString_Check(descr->d_name))
                return PyString_AS_STRING(descr->d_name);
        else
                return "?";
}

static PyObject *
descr_repr(PyDescrObject *descr, char *format)
{
        return PyString_FromFormat(format, descr_name(descr),
                                   descr->d_type->tp_name);
}

static PyObject *
method_repr(PyMethodDescrObject *descr)
{
        return descr_repr((PyDescrObject *)descr, 
                          "<method '%s' of '%s' objects>");
}

static PyObject *
member_repr(PyMemberDescrObject *descr)
{
        return descr_repr((PyDescrObject *)descr, 
                          "<member '%s' of '%s' objects>");
}

static PyObject *
getset_repr(PyGetSetDescrObject *descr)
{
        return descr_repr((PyDescrObject *)descr, 
                          "<attribute '%s' of '%s' objects>");
}

static PyObject *
wrapperdescr_repr(PyWrapperDescrObject *descr)
{
        return descr_repr((PyDescrObject *)descr, 
                          "<slot wrapper '%s' of '%s' objects>");
}

static int
descr_check(PyDescrObject *descr, PyObject *obj, PyObject **pres)
{
        if (obj == NULL) {
                Py_INCREF(descr);
                *pres = (PyObject *)descr;
                return 1;
        }
        if (!PyObject_TypeCheck(obj, descr->d_type)) {
                PyErr_Format(PyExc_TypeError,
                             "descriptor '%s' for '%s' objects "
                             "doesn't apply to '%s' object",
                             descr_name((PyDescrObject *)descr),
                             descr->d_type->tp_name,
                             obj->ob_type->tp_name);
                *pres = NULL;
                return 1;
        }
        return 0;
}

static PyObject *
classmethod_get(PyMethodDescrObject *descr, PyObject *obj, PyObject *type)
{
        /* Ensure a valid type.  Class methods ignore obj. */
        if (type == NULL) {
                if (obj != NULL)
                        type = (PyObject *)obj->ob_type;
                else {
                        /* Wot - no type?! */
                        PyErr_Format(PyExc_TypeError,
                                     "descriptor '%s' for type '%s' "
                                     "needs either an object or a type",
                                     descr_name((PyDescrObject *)descr),
                                     descr->d_type->tp_name);
                        return NULL;
                }
        }
        if (!PyType_Check(type)) {
                PyErr_Format(PyExc_TypeError,
                             "descriptor '%s' for type '%s' "
                             "needs a type, not a '%s' as arg 2",
                             descr_name((PyDescrObject *)descr),
                             descr->d_type->tp_name,
                             type->ob_type->tp_name);
                return NULL;
        }
        if (!PyType_IsSubtype((PyTypeObject *)type, descr->d_type)) {
                PyErr_Format(PyExc_TypeError,
                             "descriptor '%s' for type '%s' "
                             "doesn't apply to type '%s'",
                             descr_name((PyDescrObject *)descr),
                             descr->d_type->tp_name,
                             ((PyTypeObject *)type)->tp_name);
                return NULL;
        }
        return PyCFunction_New(descr->d_method, type);
}

static PyObject *
method_get(PyMethodDescrObject *descr, PyObject *obj, PyObject *type)
{
        PyObject *res;

        if (descr_check((PyDescrObject *)descr, obj, &res))
                return res;
        return PyCFunction_New(descr->d_method, obj);
}

static PyObject *
member_get(PyMemberDescrObject *descr, PyObject *obj, PyObject *type)
{
        PyObject *res;

        if (descr_check((PyDescrObject *)descr, obj, &res))
                return res;
        return PyMember_GetOne((char *)obj, descr->d_member);
}

static PyObject *
getset_get(PyGetSetDescrObject *descr, PyObject *obj, PyObject *type)
{
        PyObject *res;

        if (descr_check((PyDescrObject *)descr, obj, &res))
                return res;
        if (descr->d_getset->get != NULL)
                return descr->d_getset->get(obj, descr->d_getset->closure);
        PyErr_Format(PyExc_AttributeError,
                     "attribute '%.300s' of '%.100s' objects is not readable",
                     descr_name((PyDescrObject *)descr),
                     descr->d_type->tp_name);
        return NULL;
}

static PyObject *
wrapperdescr_get(PyWrapperDescrObject *descr, PyObject *obj, PyObject *type)
{
        PyObject *res;

        if (descr_check((PyDescrObject *)descr, obj, &res))
                return res;
        return PyWrapper_New((PyObject *)descr, obj);
}

static int
descr_setcheck(PyDescrObject *descr, PyObject *obj, PyObject *value,
               int *pres)
{
        assert(obj != NULL);
        if (!PyObject_TypeCheck(obj, descr->d_type)) {
                PyErr_Format(PyExc_TypeError,
                             "descriptor '%.200s' for '%.100s' objects "
                             "doesn't apply to '%.100s' object",
                             descr_name(descr),
                             descr->d_type->tp_name,
                             obj->ob_type->tp_name);
                *pres = -1;
                return 1;
        }
        return 0;
}

static int
member_set(PyMemberDescrObject *descr, PyObject *obj, PyObject *value)
{
        int res;

        if (descr_setcheck((PyDescrObject *)descr, obj, value, &res))
                return res;
        return PyMember_SetOne((char *)obj, descr->d_member, value);
}

static int
getset_set(PyGetSetDescrObject *descr, PyObject *obj, PyObject *value)
{
        int res;

        if (descr_setcheck((PyDescrObject *)descr, obj, value, &res))
                return res;
        if (descr->d_getset->set != NULL)
                return descr->d_getset->set(obj, value,
                                            descr->d_getset->closure);
        PyErr_Format(PyExc_AttributeError,
                     "attribute '%.300s' of '%.100s' objects is not writable",
                     descr_name((PyDescrObject *)descr),
                     descr->d_type->tp_name);
        return -1;
}

static PyObject *
methoddescr_call(PyMethodDescrObject *descr, PyObject *args, PyObject *kwds)
{
        Py_ssize_t argc;
        PyObject *self, *func, *result;

        /* Make sure that the first argument is acceptable as 'self' */
        assert(PyTuple_Check(args));
        argc = PyTuple_GET_SIZE(args);
        if (argc < 1) {
                PyErr_Format(PyExc_TypeError,
                             "descriptor '%.300s' of '%.100s' "
                             "object needs an argument",
                             descr_name((PyDescrObject *)descr),
                             descr->d_type->tp_name);
                return NULL;
        }
        self = PyTuple_GET_ITEM(args, 0);
        if (!PyObject_IsInstance(self, (PyObject *)(descr->d_type))) {
                PyErr_Format(PyExc_TypeError,
                             "descriptor '%.200s' "
                             "requires a '%.100s' object "
                             "but received a '%.100s'",
                             descr_name((PyDescrObject *)descr),
                             descr->d_type->tp_name,
                             self->ob_type->tp_name);
                return NULL;
        }

        func = PyCFunction_New(descr->d_method, self);
        if (func == NULL)
                return NULL;
        args = PyTuple_GetSlice(args, 1, argc);
        if (args == NULL) {
                Py_DECREF(func);
                return NULL;
        }
        result = PyEval_CallObjectWithKeywords(func, args, kwds);
        Py_DECREF(args);
        Py_DECREF(func);
        return result;
}

static PyObject *
classmethoddescr_call(PyMethodDescrObject *descr, PyObject *args,
                      PyObject *kwds)
{
        PyObject *func, *result;

        func = PyCFunction_New(descr->d_method, (PyObject *)descr->d_type);
        if (func == NULL)
                return NULL;

        result = PyEval_CallObjectWithKeywords(func, args, kwds);
        Py_DECREF(func);
        return result;
}

static PyObject *
wrapperdescr_call(PyWrapperDescrObject *descr, PyObject *args, PyObject *kwds)
{
        Py_ssize_t argc;
        PyObject *self, *func, *result;

        /* Make sure that the first argument is acceptable as 'self' */
        assert(PyTuple_Check(args));
        argc = PyTuple_GET_SIZE(args);
        if (argc < 1) {
                PyErr_Format(PyExc_TypeError,
                             "descriptor '%.300s' of '%.100s' "
                             "object needs an argument",
                             descr_name((PyDescrObject *)descr),
                             descr->d_type->tp_name);
                return NULL;
        }
        self = PyTuple_GET_ITEM(args, 0);
        if (!PyObject_IsInstance(self, (PyObject *)(descr->d_type))) {
                PyErr_Format(PyExc_TypeError,
                             "descriptor '%.200s' "
                             "requires a '%.100s' object "
                             "but received a '%.100s'",
                             descr_name((PyDescrObject *)descr),
                             descr->d_type->tp_name,
                             self->ob_type->tp_name);
                return NULL;
        }

        func = PyWrapper_New((PyObject *)descr, self);
        if (func == NULL)
                return NULL;
        args = PyTuple_GetSlice(args, 1, argc);
        if (args == NULL) {
                Py_DECREF(func);
                return NULL;
        }
        result = PyEval_CallObjectWithKeywords(func, args, kwds);
        Py_DECREF(args);
        Py_DECREF(func);
        return result;
}

static PyObject *
method_get_doc(PyMethodDescrObject *descr, void *closure)
{
        if (descr->d_method->ml_doc == NULL) {
                Py_INCREF(Py_None);
                return Py_None;
        }
        return PyString_FromString(descr->d_method->ml_doc);
}

static PyMemberDef descr_members[] = {
        {"__objclass__", T_OBJECT, offsetof(PyDescrObject, d_type), READONLY},
        {"__name__", T_OBJECT, offsetof(PyDescrObject, d_name), READONLY},
        {0}
};

static PyGetSetDef method_getset[] = {
        {"__doc__", (getter)method_get_doc},
        {0}
};

static PyObject *
member_get_doc(PyMemberDescrObject *descr, void *closure)
{
        if (descr->d_member->doc == NULL) {
                Py_INCREF(Py_None);
                return Py_None;
        }
        return PyString_FromString(descr->d_member->doc);
}

static PyGetSetDef member_getset[] = {
        {"__doc__", (getter)member_get_doc},
        {0}
};

static PyObject *
getset_get_doc(PyGetSetDescrObject *descr, void *closure)
{
        if (descr->d_getset->doc == NULL) {
                Py_INCREF(Py_None);
                return Py_None;
        }
        return PyString_FromString(descr->d_getset->doc);
}

static PyGetSetDef getset_getset[] = {
        {"__doc__", (getter)getset_get_doc},
        {0}
};

static PyObject *
wrapperdescr_get_doc(PyWrapperDescrObject *descr, void *closure)
{
        if (descr->d_base->doc == NULL) {
                Py_INCREF(Py_None);
                return Py_None;
        }
        return PyString_FromString(descr->d_base->doc);
}

static PyGetSetDef wrapperdescr_getset[] = {
        {"__doc__", (getter)wrapperdescr_get_doc},
        {0}
};

static int
descr_traverse(PyObject *self, visitproc visit, void *arg)
{
        PyDescrObject *descr = (PyDescrObject *)self;
        Py_VISIT(descr->d_type);
        return 0;
}

static PyTypeObject PyMethodDescr_Type = {
        PyVarObject_HEAD_INIT(&PyType_Type, 0)
        "method_descriptor",
        sizeof(PyMethodDescrObject),
        0,
        (destructor)descr_dealloc,              /* tp_dealloc */
        0,                                      /* tp_print */
        0,                                      /* tp_getattr */
        0,                                      /* tp_setattr */
        0,                                      /* tp_compare */
        (reprfunc)method_repr,                  /* tp_repr */
        0,                                      /* tp_as_number */
        0,                                      /* tp_as_sequence */
        0,                                      /* tp_as_mapping */
        0,                                      /* tp_hash */
        (ternaryfunc)methoddescr_call,          /* tp_call */
        0,                                      /* tp_str */
        PyObject_GenericGetAttr,                /* tp_getattro */
        0,                                      /* tp_setattro */
        0,                                      /* tp_as_buffer */
        Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
        0,                                      /* tp_doc */
        descr_traverse,                         /* tp_traverse */
        0,                                      /* tp_clear */
        0,                                      /* tp_richcompare */
        0,                                      /* tp_weaklistoffset */
        0,                                      /* tp_iter */
        0,                                      /* tp_iternext */
        0,                                      /* tp_methods */
        descr_members,                          /* tp_members */
        method_getset,                          /* tp_getset */
        0,                                      /* tp_base */
        0,                                      /* tp_dict */
        (descrgetfunc)method_get,               /* tp_descr_get */
        0,                                      /* tp_descr_set */
};

/* This is for METH_CLASS in C, not for "f = classmethod(f)" in Python! */
static PyTypeObject PyClassMethodDescr_Type = {
        PyVarObject_HEAD_INIT(&PyType_Type, 0)
        "classmethod_descriptor",
        sizeof(PyMethodDescrObject),
        0,
        (destructor)descr_dealloc,              /* tp_dealloc */
        0,                                      /* tp_print */
        0,                                      /* tp_getattr */
        0,                                      /* tp_setattr */
        0,                                      /* tp_compare */
        (reprfunc)method_repr,                  /* tp_repr */
        0,                                      /* tp_as_number */
        0,                                      /* tp_as_sequence */
        0,                                      /* tp_as_mapping */
        0,                                      /* tp_hash */
        (ternaryfunc)classmethoddescr_call,     /* tp_call */
        0,                                      /* tp_str */
        PyObject_GenericGetAttr,                /* tp_getattro */
        0,                                      /* tp_setattro */
        0,                                      /* tp_as_buffer */
        Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
        0,                                      /* tp_doc */
        descr_traverse,                         /* tp_traverse */
        0,                                      /* tp_clear */
        0,                                      /* tp_richcompare */
        0,                                      /* tp_weaklistoffset */
        0,                                      /* tp_iter */
        0,                                      /* tp_iternext */
        0,                                      /* tp_methods */
        descr_members,                          /* tp_members */
        method_getset,                          /* tp_getset */
        0,                                      /* tp_base */
        0,                                      /* tp_dict */
        (descrgetfunc)classmethod_get,          /* tp_descr_get */
        0,                                      /* tp_descr_set */
};

PyTypeObject PyMemberDescr_Type = {
        PyVarObject_HEAD_INIT(&PyType_Type, 0)
        "member_descriptor",
        sizeof(PyMemberDescrObject),
        0,
        (destructor)descr_dealloc,              /* tp_dealloc */
        0,                                      /* tp_print */
        0,                                      /* tp_getattr */
        0,                                      /* tp_setattr */
        0,                                      /* tp_compare */
        (reprfunc)member_repr,                  /* tp_repr */
        0,                                      /* tp_as_number */
        0,                                      /* tp_as_sequence */
        0,                                      /* tp_as_mapping */
        0,                                      /* tp_hash */
        0,                                      /* tp_call */
        0,                                      /* tp_str */
        PyObject_GenericGetAttr,                /* tp_getattro */
        0,                                      /* tp_setattro */
        0,                                      /* tp_as_buffer */
        Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
        0,                                      /* tp_doc */
        descr_traverse,                         /* tp_traverse */
        0,                                      /* tp_clear */
        0,                                      /* tp_richcompare */
        0,                                      /* tp_weaklistoffset */
        0,                                      /* tp_iter */
        0,                                      /* tp_iternext */
        0,                                      /* tp_methods */
        descr_members,                          /* tp_members */
        member_getset,                          /* tp_getset */
        0,                                      /* tp_base */
        0,                                      /* tp_dict */
        (descrgetfunc)member_get,               /* tp_descr_get */
        (descrsetfunc)member_set,               /* tp_descr_set */
};

PyTypeObject PyGetSetDescr_Type = {
        PyVarObject_HEAD_INIT(&PyType_Type, 0)
        "getset_descriptor",
        sizeof(PyGetSetDescrObject),
        0,
        (destructor)descr_dealloc,              /* tp_dealloc */
        0,                                      /* tp_print */
        0,                                      /* tp_getattr */
        0,                                      /* tp_setattr */
        0,                                      /* tp_compare */
        (reprfunc)getset_repr,                  /* tp_repr */
        0,                                      /* tp_as_number */
        0,                                      /* tp_as_sequence */
        0,                                      /* tp_as_mapping */
        0,                                      /* tp_hash */
        0,                                      /* tp_call */
        0,                                      /* tp_str */
        PyObject_GenericGetAttr,                /* tp_getattro */
        0,                                      /* tp_setattro */
        0,                                      /* tp_as_buffer */
        Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
        0,                                      /* tp_doc */
        descr_traverse,                         /* tp_traverse */
        0,                                      /* tp_clear */
        0,                                      /* tp_richcompare */
        0,                                      /* tp_weaklistoffset */
        0,                                      /* tp_iter */
        0,                                      /* tp_iternext */
        0,                                      /* tp_methods */
        descr_members,                          /* tp_members */
        getset_getset,                          /* tp_getset */
        0,                                      /* tp_base */
        0,                                      /* tp_dict */
        (descrgetfunc)getset_get,               /* tp_descr_get */
        (descrsetfunc)getset_set,               /* tp_descr_set */
};

PyTypeObject PyWrapperDescr_Type = {
        PyVarObject_HEAD_INIT(&PyType_Type, 0)
        "wrapper_descriptor",
        sizeof(PyWrapperDescrObject),
        0,
        (destructor)descr_dealloc,              /* tp_dealloc */
        0,                                      /* tp_print */
        0,                                      /* tp_getattr */
        0,                                      /* tp_setattr */
        0,                                      /* tp_compare */
        (reprfunc)wrapperdescr_repr,            /* tp_repr */
        0,                                      /* tp_as_number */
        0,                                      /* tp_as_sequence */
        0,                                      /* tp_as_mapping */
        0,                                      /* tp_hash */
        (ternaryfunc)wrapperdescr_call,         /* tp_call */
        0,                                      /* tp_str */
        PyObject_GenericGetAttr,                /* tp_getattro */
        0,                                      /* tp_setattro */
        0,                                      /* tp_as_buffer */
        Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
        0,                                      /* tp_doc */
        descr_traverse,                         /* tp_traverse */
        0,                                      /* tp_clear */
        0,                                      /* tp_richcompare */
        0,                                      /* tp_weaklistoffset */
        0,                                      /* tp_iter */
        0,                                      /* tp_iternext */
        0,                                      /* tp_methods */
        descr_members,                          /* tp_members */
        wrapperdescr_getset,                    /* tp_getset */
        0,                                      /* tp_base */
        0,                                      /* tp_dict */
        (descrgetfunc)wrapperdescr_get,         /* tp_descr_get */
        0,                                      /* tp_descr_set */
};

static PyDescrObject *
descr_new(PyTypeObject *descrtype, PyTypeObject *type, const char *name)
{
        PyDescrObject *descr;

        descr = (PyDescrObject *)PyType_GenericAlloc(descrtype, 0);
        if (descr != NULL) {
                Py_XINCREF(type);
                descr->d_type = type;
                descr->d_name = PyString_InternFromString(name);
                if (descr->d_name == NULL) {
                        Py_DECREF(descr);
                        descr = NULL;
                }
        }
        return descr;
}

PyObject *
PyDescr_NewMethod(PyTypeObject *type, PyMethodDef *method)
{
        PyMethodDescrObject *descr;

        descr = (PyMethodDescrObject *)descr_new(&PyMethodDescr_Type,
                                                 type, method->ml_name);
        if (descr != NULL)
                descr->d_method = method;
        return (PyObject *)descr;
}

PyObject *
PyDescr_NewClassMethod(PyTypeObject *type, PyMethodDef *method)
{
        PyMethodDescrObject *descr;

        descr = (PyMethodDescrObject *)descr_new(&PyClassMethodDescr_Type,
                                                 type, method->ml_name);
        if (descr != NULL)
                descr->d_method = method;
        return (PyObject *)descr;
}

PyObject *
PyDescr_NewMember(PyTypeObject *type, PyMemberDef *member)
{
        PyMemberDescrObject *descr;

        descr = (PyMemberDescrObject *)descr_new(&PyMemberDescr_Type,
                                                 type, member->name);
        if (descr != NULL)
                descr->d_member = member;
        return (PyObject *)descr;
}

PyObject *
PyDescr_NewGetSet(PyTypeObject *type, PyGetSetDef *getset)
{
        PyGetSetDescrObject *descr;

        descr = (PyGetSetDescrObject *)descr_new(&PyGetSetDescr_Type,
                                                 type, getset->name);
        if (descr != NULL)
                descr->d_getset = getset;
        return (PyObject *)descr;
}

PyObject *
PyDescr_NewWrapper(PyTypeObject *type, struct wrapperbase *base, void *wrapped)
{
        PyWrapperDescrObject *descr;

        descr = (PyWrapperDescrObject *)descr_new(&PyWrapperDescr_Type,
                                                 type, base->name);
        if (descr != NULL) {
                descr->d_base = base;
                descr->d_wrapped = wrapped;
        }
        return (PyObject *)descr;
}


/* --- Readonly proxy for dictionaries (actually any mapping) --- */

/* This has no reason to be in this file except that adding new files is a
   bit of a pain */

typedef struct {
        PyObject_HEAD
        PyObject *dict;
} proxyobject;

static Py_ssize_t
proxy_len(proxyobject *pp)
{
        return PyObject_Size(pp->dict);
}

static PyObject *
proxy_getitem(proxyobject *pp, PyObject *key)
{
        return PyObject_GetItem(pp->dict, key);
}

static PyMappingMethods proxy_as_mapping = {
        (lenfunc)proxy_len,                     /* mp_length */
        (binaryfunc)proxy_getitem,              /* mp_subscript */
        0,                                      /* mp_ass_subscript */
};

static int
proxy_contains(proxyobject *pp, PyObject *key)
{
        return PyDict_Contains(pp->dict, key);
}

static PySequenceMethods proxy_as_sequence = {
        0,                                      /* sq_length */
        0,                                      /* sq_concat */
        0,                                      /* sq_repeat */
        0,                                      /* sq_item */
        0,                                      /* sq_slice */
        0,                                      /* sq_ass_item */
        0,                                      /* sq_ass_slice */
        (objobjproc)proxy_contains,             /* sq_contains */
        0,                                      /* sq_inplace_concat */
        0,                                      /* sq_inplace_repeat */
};

static PyObject *
proxy_has_key(proxyobject *pp, PyObject *key)
{
        int res = PyDict_Contains(pp->dict, key);
        if (res < 0)
                return NULL;
        return PyBool_FromLong(res);
}

static PyObject *
proxy_get(proxyobject *pp, PyObject *args)
{
        PyObject *key, *def = Py_None;

        if (!PyArg_UnpackTuple(args, "get", 1, 2, &key, &def))
                return NULL;
        return PyObject_CallMethod(pp->dict, "get", "(OO)", key, def);
}

static PyObject *
proxy_keys(proxyobject *pp)
{
        return PyMapping_Keys(pp->dict);
}

static PyObject *
proxy_values(proxyobject *pp)
{
        return PyMapping_Values(pp->dict);
}

static PyObject *
proxy_items(proxyobject *pp)
{
        return PyMapping_Items(pp->dict);
}

static PyObject *
proxy_iterkeys(proxyobject *pp)
{
        return PyObject_CallMethod(pp->dict, "iterkeys", NULL);
}

static PyObject *
proxy_itervalues(proxyobject *pp)
{
        return PyObject_CallMethod(pp->dict, "itervalues", NULL);
}

static PyObject *
proxy_iteritems(proxyobject *pp)
{
        return PyObject_CallMethod(pp->dict, "iteritems", NULL);
}
static PyObject *
proxy_copy(proxyobject *pp)
{
        return PyObject_CallMethod(pp->dict, "copy", NULL);
}

static PyMethodDef proxy_methods[] = {
        {"has_key",   (PyCFunction)proxy_has_key,    METH_O,
         PyDoc_STR("D.has_key(k) -> True if D has a key k, else False")},
        {"get",       (PyCFunction)proxy_get,        METH_VARARGS,
         PyDoc_STR("D.get(k[,d]) -> D[k] if D.has_key(k), else d."
                                        "  d defaults to None.")},
        {"keys",      (PyCFunction)proxy_keys,       METH_NOARGS,
         PyDoc_STR("D.keys() -> list of D's keys")},
        {"values",    (PyCFunction)proxy_values,     METH_NOARGS,
         PyDoc_STR("D.values() -> list of D's values")},
        {"items",     (PyCFunction)proxy_items,      METH_NOARGS,
         PyDoc_STR("D.items() -> list of D's (key, value) pairs, as 2-tuples")},
        {"iterkeys",  (PyCFunction)proxy_iterkeys,   METH_NOARGS,
         PyDoc_STR("D.iterkeys() -> an iterator over the keys of D")},
        {"itervalues",(PyCFunction)proxy_itervalues, METH_NOARGS,
         PyDoc_STR("D.itervalues() -> an iterator over the values of D")},
        {"iteritems", (PyCFunction)proxy_iteritems,  METH_NOARGS,
         PyDoc_STR("D.iteritems() ->"
                   " an iterator over the (key, value) items of D")},
        {"copy",      (PyCFunction)proxy_copy,       METH_NOARGS,
         PyDoc_STR("D.copy() -> a shallow copy of D")},
        {0}
};

static void
proxy_dealloc(proxyobject *pp)
{
        _PyObject_GC_UNTRACK(pp);
        Py_DECREF(pp->dict);
        PyObject_GC_Del(pp);
}

static PyObject *
proxy_getiter(proxyobject *pp)
{
        return PyObject_GetIter(pp->dict);
}

static PyObject *
proxy_str(proxyobject *pp)
{
        return PyObject_Str(pp->dict);
}

static int
proxy_traverse(PyObject *self, visitproc visit, void *arg)
{
        proxyobject *pp = (proxyobject *)self;
        Py_VISIT(pp->dict);
        return 0;
}

static int
proxy_compare(proxyobject *v, PyObject *w)
{
        return PyObject_Compare(v->dict, w);
}

static PyObject *
proxy_richcompare(proxyobject *v, PyObject *w, int op)
{
        return PyObject_RichCompare(v->dict, w, op);
}

PyTypeObject PyDictProxy_Type = {
        PyVarObject_HEAD_INIT(&PyType_Type, 0)
        "dictproxy",                            /* tp_name */
        sizeof(proxyobject),                    /* tp_basicsize */
        0,                                      /* tp_itemsize */
        /* methods */
        (destructor)proxy_dealloc,              /* tp_dealloc */
        0,                                      /* tp_print */
        0,                                      /* tp_getattr */
        0,                                      /* tp_setattr */
        (cmpfunc)proxy_compare,                 /* tp_compare */
        0,                                      /* tp_repr */
        0,                                      /* tp_as_number */
        &proxy_as_sequence,                     /* tp_as_sequence */
        &proxy_as_mapping,                      /* tp_as_mapping */
        0,                                      /* tp_hash */
        0,                                      /* tp_call */
        (reprfunc)proxy_str,                    /* tp_str */
        PyObject_GenericGetAttr,                /* tp_getattro */
        0,                                      /* tp_setattro */
        0,                                      /* tp_as_buffer */
        Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
        0,                                      /* tp_doc */
        proxy_traverse,                         /* tp_traverse */
        0,                                      /* tp_clear */
        (richcmpfunc)proxy_richcompare,         /* tp_richcompare */
        0,                                      /* tp_weaklistoffset */
        (getiterfunc)proxy_getiter,             /* tp_iter */
        0,                                      /* tp_iternext */
        proxy_methods,                          /* tp_methods */
        0,                                      /* tp_members */
        0,                                      /* tp_getset */
        0,                                      /* tp_base */
        0,                                      /* tp_dict */
        0,                                      /* tp_descr_get */
        0,                                      /* tp_descr_set */
};

PyObject *
PyDictProxy_New(PyObject *dict)
{
        proxyobject *pp;

        pp = PyObject_GC_New(proxyobject, &PyDictProxy_Type);
        if (pp != NULL) {
                Py_INCREF(dict);
                pp->dict = dict;
                _PyObject_GC_TRACK(pp);
        }
        return (PyObject *)pp;
}


/* --- Wrapper object for "slot" methods --- */

/* This has no reason to be in this file except that adding new files is a
   bit of a pain */

typedef struct {
        PyObject_HEAD
        PyWrapperDescrObject *descr;
        PyObject *self;
} wrapperobject;

static void
wrapper_dealloc(wrapperobject *wp)
{
        PyObject_GC_UnTrack(wp);
        Py_TRASHCAN_SAFE_BEGIN(wp)
        Py_XDECREF(wp->descr);
        Py_XDECREF(wp->self);
        PyObject_GC_Del(wp);
        Py_TRASHCAN_SAFE_END(wp)
}

static int
wrapper_compare(wrapperobject *a, wrapperobject *b)
{
        if (a->descr == b->descr)
                return PyObject_Compare(a->self, b->self);
        else
                return (a->descr < b->descr) ? -1 : 1;
}

static long
wrapper_hash(wrapperobject *wp)
{
        int x, y;
        x = _Py_HashPointer(wp->descr);
        if (x == -1)
                return -1;
        y = PyObject_Hash(wp->self);
        if (y == -1)
                return -1;
        x = x ^ y;
        if (x == -1)
                x = -2;
        return x;
}

static PyObject *
wrapper_repr(wrapperobject *wp)
{
        return PyString_FromFormat("<method-wrapper '%s' of %s object at %p>",
                                   wp->descr->d_base->name,
                                   wp->self->ob_type->tp_name,
                                   wp->self);
}

static PyMemberDef wrapper_members[] = {
        {"__self__", T_OBJECT, offsetof(wrapperobject, self), READONLY},
        {0}
};

static PyObject *
wrapper_objclass(wrapperobject *wp)
{
        PyObject *c = (PyObject *)wp->descr->d_type;

        Py_INCREF(c);
        return c;
}

static PyObject *
wrapper_name(wrapperobject *wp)
{
        char *s = wp->descr->d_base->name;

        return PyString_FromString(s);
}

static PyObject *
wrapper_doc(wrapperobject *wp)
{
        char *s = wp->descr->d_base->doc;

        if (s == NULL) {
                Py_INCREF(Py_None);
                return Py_None;
        }
        else {
                return PyString_FromString(s);
        }
}

static PyGetSetDef wrapper_getsets[] = {
        {"__objclass__", (getter)wrapper_objclass},
        {"__name__", (getter)wrapper_name},
        {"__doc__", (getter)wrapper_doc},
        {0}
};

static PyObject *
wrapper_call(wrapperobject *wp, PyObject *args, PyObject *kwds)
{
        wrapperfunc wrapper = wp->descr->d_base->wrapper;
        PyObject *self = wp->self;

        if (wp->descr->d_base->flags & PyWrapperFlag_KEYWORDS) {
                wrapperfunc_kwds wk = (wrapperfunc_kwds)wrapper;
                return (*wk)(self, args, wp->descr->d_wrapped, kwds);
        }

        if (kwds != NULL && (!PyDict_Check(kwds) || PyDict_Size(kwds) != 0)) {
                PyErr_Format(PyExc_TypeError,
                             "wrapper %s doesn't take keyword arguments",
                             wp->descr->d_base->name);
                return NULL;
        }
        return (*wrapper)(self, args, wp->descr->d_wrapped);
}

static int
wrapper_traverse(PyObject *self, visitproc visit, void *arg)
{
        wrapperobject *wp = (wrapperobject *)self;
        Py_VISIT(wp->descr);
        Py_VISIT(wp->self);
        return 0;
}

static PyTypeObject wrappertype = {
        PyVarObject_HEAD_INIT(&PyType_Type, 0)
        "method-wrapper",                       /* tp_name */
        sizeof(wrapperobject),                  /* tp_basicsize */
        0,                                      /* tp_itemsize */
        /* methods */
        (destructor)wrapper_dealloc,            /* tp_dealloc */
        0,                                      /* tp_print */
        0,                                      /* tp_getattr */
        0,                                      /* tp_setattr */
        (cmpfunc)wrapper_compare,               /* tp_compare */
        (reprfunc)wrapper_repr,                 /* tp_repr */
        0,                                      /* tp_as_number */
        0,                                      /* tp_as_sequence */
        0,                                      /* tp_as_mapping */
        (hashfunc)wrapper_hash,                 /* tp_hash */
        (ternaryfunc)wrapper_call,              /* tp_call */
        0,                                      /* tp_str */
        PyObject_GenericGetAttr,                /* tp_getattro */
        0,                                      /* tp_setattro */
        0,                                      /* tp_as_buffer */
        Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
        0,                                      /* tp_doc */
        wrapper_traverse,                       /* tp_traverse */
        0,                                      /* tp_clear */
        0,                                      /* tp_richcompare */
        0,                                      /* tp_weaklistoffset */
        0,                                      /* tp_iter */
        0,                                      /* tp_iternext */
        0,                                      /* tp_methods */
        wrapper_members,                        /* tp_members */
        wrapper_getsets,                        /* tp_getset */
        0,                                      /* tp_base */
        0,                                      /* tp_dict */
        0,                                      /* tp_descr_get */
        0,                                      /* tp_descr_set */
};

PyObject *
PyWrapper_New(PyObject *d, PyObject *self)
{
        wrapperobject *wp;
        PyWrapperDescrObject *descr;

        assert(PyObject_TypeCheck(d, &PyWrapperDescr_Type));
        descr = (PyWrapperDescrObject *)d;
        assert(PyObject_IsInstance(self, (PyObject *)(descr->d_type)));

        wp = PyObject_GC_New(wrapperobject, &wrappertype);
        if (wp != NULL) {
                Py_INCREF(descr);
                wp->descr = descr;
                Py_INCREF(self);
                wp->self = self;
                _PyObject_GC_TRACK(wp);
        }
        return (PyObject *)wp;
}


/* A built-in 'property' type */

/*
    class property(object):

        def __init__(self, fget=None, fset=None, fdel=None, doc=None):
            if doc is None and fget is not None and hasattr(fget, "__doc__"):
                doc = fget.__doc__
            self.__get = fget
            self.__set = fset
            self.__del = fdel
            self.__doc__ = doc

        def __get__(self, inst, type=None):
            if inst is None:
                return self
            if self.__get is None:
                raise AttributeError, "unreadable attribute"
            return self.__get(inst)

        def __set__(self, inst, value):
            if self.__set is None:
                raise AttributeError, "can't set attribute"
            return self.__set(inst, value)

        def __delete__(self, inst):
            if self.__del is None:
                raise AttributeError, "can't delete attribute"
            return self.__del(inst)

*/

typedef struct {
        PyObject_HEAD
        PyObject *prop_get;
        PyObject *prop_set;
        PyObject *prop_del;
        PyObject *prop_doc;
        int getter_doc;
} propertyobject;

static PyObject * property_copy(PyObject *, PyObject *, PyObject *,
                                  PyObject *, PyObject *);

static PyMemberDef property_members[] = {
        {"fget", T_OBJECT, offsetof(propertyobject, prop_get), READONLY},
        {"fset", T_OBJECT, offsetof(propertyobject, prop_set), READONLY},
        {"fdel", T_OBJECT, offsetof(propertyobject, prop_del), READONLY},
        {"__doc__",  T_OBJECT, offsetof(propertyobject, prop_doc), READONLY},
        {0}
};


PyDoc_STRVAR(getter_doc,
             "Descriptor to change the getter on a property.");

static PyObject *
property_getter(PyObject *self, PyObject *getter)
{
        return property_copy(self, getter, NULL, NULL, NULL);
}


PyDoc_STRVAR(setter_doc,
             "Descriptor to change the setter on a property.");

static PyObject *
property_setter(PyObject *self, PyObject *setter)
{
        return property_copy(self, NULL, setter, NULL, NULL);
}


PyDoc_STRVAR(deleter_doc,
             "Descriptor to change the deleter on a property.");

static PyObject *
property_deleter(PyObject *self, PyObject *deleter)
{
        return property_copy(self, NULL, NULL, deleter, NULL);
}


static PyMethodDef property_methods[] = {
        {"getter", property_getter, METH_O, getter_doc},
        {"setter", property_setter, METH_O, setter_doc},
        {"deleter", property_deleter, METH_O, deleter_doc},
        {0}
};


static void
property_dealloc(PyObject *self)
{
        propertyobject *gs = (propertyobject *)self;

        _PyObject_GC_UNTRACK(self);
        Py_XDECREF(gs->prop_get);
        Py_XDECREF(gs->prop_set);
        Py_XDECREF(gs->prop_del);
        Py_XDECREF(gs->prop_doc);
        self->ob_type->tp_free(self);
}

static PyObject *
property_descr_get(PyObject *self, PyObject *obj, PyObject *type)
{
        propertyobject *gs = (propertyobject *)self;

        if (obj == NULL || obj == Py_None) {
                Py_INCREF(self);
                return self;
        }
        if (gs->prop_get == NULL) {
                PyErr_SetString(PyExc_AttributeError, "unreadable attribute");
                return NULL;
        }
        return PyObject_CallFunction(gs->prop_get, "(O)", obj);
}

static int
property_descr_set(PyObject *self, PyObject *obj, PyObject *value)
{
        propertyobject *gs = (propertyobject *)self;
        PyObject *func, *res;

        if (value == NULL)
                func = gs->prop_del;
        else
                func = gs->prop_set;
        if (func == NULL) {
                PyErr_SetString(PyExc_AttributeError,
                                value == NULL ?
                                "can't delete attribute" :
                                "can't set attribute");
                return -1;
        }
        if (value == NULL)
                res = PyObject_CallFunction(func, "(O)", obj);
        else
                res = PyObject_CallFunction(func, "(OO)", obj, value);
        if (res == NULL)
                return -1;
        Py_DECREF(res);
        return 0;
}

static PyObject *
property_copy(PyObject *old, PyObject *get, PyObject *set, PyObject *del,
                PyObject *doc)
{
        propertyobject *pold = (propertyobject *)old;
        PyObject *new, *type;

        type = PyObject_Type(old);
        if (type == NULL)
                return NULL;

        if (get == NULL || get == Py_None) {
                Py_XDECREF(get);
                get = pold->prop_get ? pold->prop_get : Py_None;
        }
        if (set == NULL || set == Py_None) {
                Py_XDECREF(set);
                set = pold->prop_set ? pold->prop_set : Py_None;
        }
        if (del == NULL || del == Py_None) {
                Py_XDECREF(del);
                del = pold->prop_del ? pold->prop_del : Py_None;
        }
        if (doc == NULL || doc == Py_None) {
                Py_XDECREF(doc);
                if (pold->getter_doc && get != Py_None) {
                        /* make _init use __doc__ from getter */
                        doc = Py_None;
                }
                else {
                        doc = pold->prop_doc ? pold->prop_doc : Py_None;
                }
        }

        new =  PyObject_CallFunction(type, "OOOO", get, set, del, doc);
        Py_DECREF(type);
        if (new == NULL)
                return NULL;
        return new;
}

static int
property_init(PyObject *self, PyObject *args, PyObject *kwds)
{
        PyObject *get = NULL, *set = NULL, *del = NULL, *doc = NULL;
        static char *kwlist[] = {"fget", "fset", "fdel", "doc", 0};
        propertyobject *prop = (propertyobject *)self;
        
        if (!PyArg_ParseTupleAndKeywords(args, kwds, "|OOOO:property",
                                         kwlist, &get, &set, &del, &doc))
                return -1;

        if (get == Py_None)
                get = NULL;
        if (set == Py_None)
                set = NULL;
        if (del == Py_None)
                del = NULL;

        Py_XINCREF(get);
        Py_XINCREF(set);
        Py_XINCREF(del);
        Py_XINCREF(doc);

        prop->prop_get = get;
        prop->prop_set = set;
        prop->prop_del = del;
        prop->prop_doc = doc;
        prop->getter_doc = 0;

        /* if no docstring given and the getter has one, use that one */
        if ((doc == NULL || doc == Py_None) && get != NULL) {
                PyObject *get_doc = PyObject_GetAttrString(get, "__doc__");
                if (get_doc != NULL) {
                        /* get_doc already INCREF'd by GetAttr */
                        if (Py_TYPE(self)==&PyProperty_Type) {
                                Py_XDECREF(prop->prop_doc);
                                prop->prop_doc = get_doc;
                        } else {
                                /* Put __doc__ in dict of the subclass instance instead,
                                otherwise it gets shadowed by class's __doc__. */
                                if (PyObject_SetAttrString(self, "__doc__", get_doc) != 0)
                                {
                                        /* DECREF for props handled by _dealloc */
                                        Py_DECREF(get_doc);
                                        return -1;
                                }
                                Py_DECREF(get_doc);
                        }
                        prop->getter_doc = 1;
                } else {
                        PyErr_Clear();
                }
        }

        return 0;
}

PyDoc_STRVAR(property_doc,
"property(fget=None, fset=None, fdel=None, doc=None) -> property attribute\n"
"\n"
"fget is a function to be used for getting an attribute value, and likewise\n"
"fset is a function for setting, and fdel a function for del'ing, an\n"
"attribute.  Typical use is to define a managed attribute x:\n"
"class C(object):\n"
"    def getx(self): return self._x\n"
"    def setx(self, value): self._x = value\n"
"    def delx(self): del self._x\n"
"    x = property(getx, setx, delx, \"I'm the 'x' property.\")\n"
"\n"
"Decorators make defining new properties or modifying existing ones easy:\n"
"class C(object):\n"
"    @property\n"
"    def x(self): return self._x\n"
"    @x.setter\n"
"    def x(self, value): self._x = value\n"
"    @x.deleter\n"
"    def x(self): del self._x\n"
);

static int
property_traverse(PyObject *self, visitproc visit, void *arg)
{
        propertyobject *pp = (propertyobject *)self;
        Py_VISIT(pp->prop_get);
        Py_VISIT(pp->prop_set);
        Py_VISIT(pp->prop_del);
        Py_VISIT(pp->prop_doc);
        return 0;
}

PyTypeObject PyProperty_Type = {
        PyVarObject_HEAD_INIT(&PyType_Type, 0)
        "property",                             /* tp_name */
        sizeof(propertyobject),                 /* tp_basicsize */
        0,                                      /* tp_itemsize */
        /* methods */
        property_dealloc,                       /* tp_dealloc */
        0,                                      /* tp_print */
        0,                                      /* tp_getattr */
        0,                                      /* tp_setattr */
        0,                                      /* tp_compare */
        0,                                      /* tp_repr */
        0,                                      /* tp_as_number */
        0,                                      /* tp_as_sequence */
        0,                                      /* tp_as_mapping */
        0,                                      /* tp_hash */
        0,                                      /* tp_call */
        0,                                      /* tp_str */
        PyObject_GenericGetAttr,                /* tp_getattro */
        0,                                      /* tp_setattro */
        0,                                      /* tp_as_buffer */
        Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
                Py_TPFLAGS_BASETYPE,            /* tp_flags */
        property_doc,                           /* tp_doc */
        property_traverse,                      /* tp_traverse */
        0,                                      /* tp_clear */
        0,                                      /* tp_richcompare */
        0,                                      /* tp_weaklistoffset */
        0,                                      /* tp_iter */
        0,                                      /* tp_iternext */
        property_methods,                       /* tp_methods */
        property_members,                       /* tp_members */
        0,                                      /* tp_getset */
        0,                                      /* tp_base */
        0,                                      /* tp_dict */
        property_descr_get,                     /* tp_descr_get */
        property_descr_set,                     /* tp_descr_set */
        0,                                      /* tp_dictoffset */
        property_init,                          /* tp_init */
        PyType_GenericAlloc,                    /* tp_alloc */
        PyType_GenericNew,                      /* tp_new */
        PyObject_GC_Del,                        /* tp_free */
};