Objects/descrobject.c

   1 /* Descriptors -- a new, flexible way to describe attributes */
   2
   3 #include "Python.h"
   4 #include "structmember.h" /* Why is this not included in Python.h? */
   5
   6 static void
   7 descr_dealloc(PyDescrObject *descr)
   8 {
   9         _PyObject_GC_UNTRACK(descr);
  10         Py_XDECREF(descr->d_type);
  11         Py_XDECREF(descr->d_name);
  12         PyObject_GC_Del(descr);
  13 }
  14
  15 static char *
  16 descr_name(PyDescrObject *descr)
  17 {
  18         if (descr->d_name != NULL && PyString_Check(descr->d_name))
  19                 return PyString_AS_STRING(descr->d_name);
  20         else
  21                 return "?";
  22 }
  23
  24 static PyObject *
  25 descr_repr(PyDescrObject *descr, char *format)
  26 {
  27         return PyString_FromFormat(format, descr_name(descr),
  28                                    descr->d_type->tp_name);
  29 }
  30
  31 static PyObject *
  32 method_repr(PyMethodDescrObject *descr)
  33 {
  34         return descr_repr((PyDescrObject *)descr,
  35                           "<method '%s' of '%s' objects>");
  36 }
  37
  38 static PyObject *
  39 member_repr(PyMemberDescrObject *descr)
  40 {
  41         return descr_repr((PyDescrObject *)descr,
  42                           "<member '%s' of '%s' objects>");
  43 }
  44
  45 static PyObject *
  46 getset_repr(PyGetSetDescrObject *descr)
  47 {
  48         return descr_repr((PyDescrObject *)descr,
  49                           "<attribute '%s' of '%s' objects>");
  50 }
  51
  52 static PyObject *
  53 wrapperdescr_repr(PyWrapperDescrObject *descr)
  54 {
  55         return descr_repr((PyDescrObject *)descr,
  56                           "<slot wrapper '%s' of '%s' objects>");
  57 }
  58
  59 static int
  60 descr_check(PyDescrObject *descr, PyObject *obj, PyObject **pres)
  61 {
  62         if (obj == NULL) {
  63                 Py_INCREF(descr);
  64                 *pres = (PyObject *)descr;
  65                 return 1;
  66         }
  67         if (!PyObject_TypeCheck(obj, descr->d_type)) {
  68                 PyErr_Format(PyExc_TypeError,
  69                              "descriptor '%s' for '%s' objects "
  70                              "doesn't apply to '%s' object",
  71                              descr_name((PyDescrObject *)descr),
  72                              descr->d_type->tp_name,
  73                              obj->ob_type->tp_name);
  74                 *pres = NULL;
  75                 return 1;
  76         }
  77         return 0;
  78 }
  79
  80 static PyObject *
  81 classmethod_get(PyMethodDescrObject *descr, PyObject *obj, PyObject *type)
  82 {
  83         /* Ensure a valid type.  Class methods ignore obj. */
  84         if (type == NULL) {
  85                 if (obj != NULL)
  86                         type = (PyObject *)obj->ob_type;
  87                 else {
  88                         /* Wot - no type?! */
  89                         PyErr_Format(PyExc_TypeError,
  90                                      "descriptor '%s' for type '%s' "
  91                                      "needs either an object or a type",
  92                                      descr_name((PyDescrObject *)descr),
  93                                      descr->d_type->tp_name);
  94                         return NULL;
  95                 }
  96         }
  97         if (!PyType_Check(type)) {
  98                 PyErr_Format(PyExc_TypeError,
  99                              "descriptor '%s' for type '%s' "
 100                              "needs a type, not a '%s' as arg 2",
 101                              descr_name((PyDescrObject *)descr),
 102                              descr->d_type->tp_name,
 103                              type->ob_type->tp_name);
 104                 return NULL;
 105         }
 106         if (!PyType_IsSubtype((PyTypeObject *)type, descr->d_type)) {
 107                 PyErr_Format(PyExc_TypeError,
 108                              "descriptor '%s' for type '%s' "
 109                              "doesn't apply to type '%s'",
 110                              descr_name((PyDescrObject *)descr),
 111                              descr->d_type->tp_name,
 112                              ((PyTypeObject *)type)->tp_name);
 113                 return NULL;
 114         }
 115         return PyCFunction_New(descr->d_method, type);
 116 }
 117
 118 static PyObject *
 119 method_get(PyMethodDescrObject *descr, PyObject *obj, PyObject *type)
 120 {
 121         PyObject *res;
 122
 123         if (descr_check((PyDescrObject *)descr, obj, &res))
 124                 return res;
 125         return PyCFunction_New(descr->d_method, obj);
 126 }
 127
 128 static PyObject *
 129 member_get(PyMemberDescrObject *descr, PyObject *obj, PyObject *type)
 130 {
 131         PyObject *res;
 132
 133         if (descr_check((PyDescrObject *)descr, obj, &res))
 134                 return res;
 135         return PyMember_GetOne((char *)obj, descr->d_member);
 136 }
 137
 138 static PyObject *
 139 getset_get(PyGetSetDescrObject *descr, PyObject *obj, PyObject *type)
 140 {
 141         PyObject *res;
 142
 143         if (descr_check((PyDescrObject *)descr, obj, &res))
 144                 return res;
 145         if (descr->d_getset->get != NULL)
 146                 return descr->d_getset->get(obj, descr->d_getset->closure);
 147         PyErr_Format(PyExc_AttributeError,
 148                      "attribute '%.300s' of '%.100s' objects is not readable",
 149                      descr_name((PyDescrObject *)descr),
 150                      descr->d_type->tp_name);
 151         return NULL;
 152 }
 153
 154 static PyObject *
 155 wrapperdescr_get(PyWrapperDescrObject *descr, PyObject *obj, PyObject *type)
 156 {
 157         PyObject *res;
 158
 159         if (descr_check((PyDescrObject *)descr, obj, &res))
 160                 return res;
 161         return PyWrapper_New((PyObject *)descr, obj);
 162 }
 163
 164 static int
 165 descr_setcheck(PyDescrObject *descr, PyObject *obj, PyObject *value,
 166                int *pres)
 167 {
 168         assert(obj != NULL);
 169         if (!PyObject_TypeCheck(obj, descr->d_type)) {
 170                 PyErr_Format(PyExc_TypeError,
 171                              "descriptor '%.200s' for '%.100s' objects "
 172                              "doesn't apply to '%.100s' object",
 173                              descr_name(descr),
 174                              descr->d_type->tp_name,
 175                              obj->ob_type->tp_name);
 176                 *pres = -1;
 177                 return 1;
 178         }
 179         return 0;
 180 }
 181
 182 static int
 183 member_set(PyMemberDescrObject *descr, PyObject *obj, PyObject *value)
 184 {
 185         int res;
 186
 187         if (descr_setcheck((PyDescrObject *)descr, obj, value, &res))
 188                 return res;
 189         return PyMember_SetOne((char *)obj, descr->d_member, value);
 190 }
 191
 192 static int
 193 getset_set(PyGetSetDescrObject *descr, PyObject *obj, PyObject *value)
 194 {
 195         int res;
 196
 197         if (descr_setcheck((PyDescrObject *)descr, obj, value, &res))
 198                 return res;
 199         if (descr->d_getset->set != NULL)
 200                 return descr->d_getset->set(obj, value,
 201                                             descr->d_getset->closure);
 202         PyErr_Format(PyExc_AttributeError,
 203                      "attribute '%.300s' of '%.100s' objects is not writable",
 204                      descr_name((PyDescrObject *)descr),
 205                      descr->d_type->tp_name);
 206         return -1;
 207 }
 208
 209 static PyObject *
 210 methoddescr_call(PyMethodDescrObject *descr, PyObject *args, PyObject *kwds)
 211 {
 212         Py_ssize_t argc;
 213         PyObject *self, *func, *result;
 214
 215         /* Make sure that the first argument is acceptable as 'self' */
 216         assert(PyTuple_Check(args));
 217         argc = PyTuple_GET_SIZE(args);
 218         if (argc < 1) {
 219                 PyErr_Format(PyExc_TypeError,
 220                              "descriptor '%.300s' of '%.100s' "
 221                              "object needs an argument",
 222                              descr_name((PyDescrObject *)descr),
 223                              descr->d_type->tp_name);
 224                 return NULL;
 225         }
 226         self = PyTuple_GET_ITEM(args, 0);
 227         if (!PyObject_IsInstance(self, (PyObject *)(descr->d_type))) {
 228                 PyErr_Format(PyExc_TypeError,
 229                              "descriptor '%.200s' "
 230                              "requires a '%.100s' object "
 231                              "but received a '%.100s'",
 232                              descr_name((PyDescrObject *)descr),
 233                              descr->d_type->tp_name,
 234                              self->ob_type->tp_name);
 235                 return NULL;
 236         }
 237
 238         func = PyCFunction_New(descr->d_method, self);
 239         if (func == NULL)
 240                 return NULL;
 241         args = PyTuple_GetSlice(args, 1, argc);
 242         if (args == NULL) {
 243                 Py_DECREF(func);
 244                 return NULL;
 245         }
 246         result = PyEval_CallObjectWithKeywords(func, args, kwds);
 247         Py_DECREF(args);
 248         Py_DECREF(func);
 249         return result;
 250 }
 251
 252 static PyObject *
 253 classmethoddescr_call(PyMethodDescrObject *descr, PyObject *args,
 254                       PyObject *kwds)
 255 {
 256         PyObject *func, *result;
 257
 258         func = PyCFunction_New(descr->d_method, (PyObject *)descr->d_type);
 259         if (func == NULL)
 260                 return NULL;
 261
 262         result = PyEval_CallObjectWithKeywords(func, args, kwds);
 263         Py_DECREF(func);
 264         return result;
 265 }
 266
 267 static PyObject *
 268 wrapperdescr_call(PyWrapperDescrObject *descr, PyObject *args, PyObject *kwds)
 269 {
 270         Py_ssize_t argc;
 271         PyObject *self, *func, *result;
 272
 273         /* Make sure that the first argument is acceptable as 'self' */
 274         assert(PyTuple_Check(args));
 275         argc = PyTuple_GET_SIZE(args);
 276         if (argc < 1) {
 277                 PyErr_Format(PyExc_TypeError,
 278                              "descriptor '%.300s' of '%.100s' "
 279                              "object needs an argument",
 280                              descr_name((PyDescrObject *)descr),
 281                              descr->d_type->tp_name);
 282                 return NULL;
 283         }
 284         self = PyTuple_GET_ITEM(args, 0);
 285         if (!PyObject_IsInstance(self, (PyObject *)(descr->d_type))) {
 286                 PyErr_Format(PyExc_TypeError,
 287                              "descriptor '%.200s' "
 288                              "requires a '%.100s' object "
 289                              "but received a '%.100s'",
 290                              descr_name((PyDescrObject *)descr),
 291                              descr->d_type->tp_name,
 292                              self->ob_type->tp_name);
 293                 return NULL;
 294         }
 295
 296         func = PyWrapper_New((PyObject *)descr, self);
 297         if (func == NULL)
 298                 return NULL;
 299         args = PyTuple_GetSlice(args, 1, argc);
 300         if (args == NULL) {
 301                 Py_DECREF(func);
 302                 return NULL;
 303         }
 304         result = PyEval_CallObjectWithKeywords(func, args, kwds);
 305         Py_DECREF(args);
 306         Py_DECREF(func);
 307         return result;
 308 }
 309
 310 static PyObject *
 311 method_get_doc(PyMethodDescrObject *descr, void *closure)
 312 {
 313         if (descr->d_method->ml_doc == NULL) {
 314                 Py_INCREF(Py_None);
 315                 return Py_None;
 316         }
 317         return PyString_FromString(descr->d_method->ml_doc);
 318 }
 319
 320 static PyMemberDef descr_members[] = {
 321         {"__objclass__", T_OBJECT, offsetof(PyDescrObject, d_type), READONLY},
 322         {"__name__", T_OBJECT, offsetof(PyDescrObject, d_name), READONLY},
 323         {0}
 324 };
 325
 326 static PyGetSetDef method_getset[] = {
 327         {"__doc__", (getter)method_get_doc},
 328         {0}
 329 };
 330
 331 static PyObject *
 332 member_get_doc(PyMemberDescrObject *descr, void *closure)
 333 {
 334         if (descr->d_member->doc == NULL) {
 335                 Py_INCREF(Py_None);
 336                 return Py_None;
 337         }
 338         return PyString_FromString(descr->d_member->doc);
 339 }
 340
 341 static PyGetSetDef member_getset[] = {
 342         {"__doc__", (getter)member_get_doc},
 343         {0}
 344 };
 345
 346 static PyObject *
 347 getset_get_doc(PyGetSetDescrObject *descr, void *closure)
 348 {
 349         if (descr->d_getset->doc == NULL) {
 350                 Py_INCREF(Py_None);
 351                 return Py_None;
 352         }
 353         return PyString_FromString(descr->d_getset->doc);
 354 }
 355
 356 static PyGetSetDef getset_getset[] = {
 357         {"__doc__", (getter)getset_get_doc},
 358         {0}
 359 };
 360
 361 static PyObject *
 362 wrapperdescr_get_doc(PyWrapperDescrObject *descr, void *closure)
 363 {
 364         if (descr->d_base->doc == NULL) {
 365                 Py_INCREF(Py_None);
 366                 return Py_None;
 367         }
 368         return PyString_FromString(descr->d_base->doc);
 369 }
 370
 371 static PyGetSetDef wrapperdescr_getset[] = {
 372         {"__doc__", (getter)wrapperdescr_get_doc},
 373         {0}
 374 };
 375
 376 static int
 377 descr_traverse(PyObject *self, visitproc visit, void *arg)
 378 {
 379         PyDescrObject *descr = (PyDescrObject *)self;
 380         Py_VISIT(descr->d_type);
 381         return 0;
 382 }
 383
 384 static PyTypeObject PyMethodDescr_Type = {
 385         PyVarObject_HEAD_INIT(&PyType_Type, 0)
 386         "method_descriptor",
 387         sizeof(PyMethodDescrObject),
 388         0,
 389         (destructor)descr_dealloc,              /* tp_dealloc */
 390         0,                                      /* tp_print */
 391         0,                                      /* tp_getattr */
 392         0,                                      /* tp_setattr */
 393         0,                                      /* tp_compare */
 394         (reprfunc)method_repr,                  /* tp_repr */
 395         0,                                      /* tp_as_number */
 396         0,                                      /* tp_as_sequence */
 397         0,                                      /* tp_as_mapping */
 398         0,                                      /* tp_hash */
 399         (ternaryfunc)methoddescr_call,          /* tp_call */
 400         0,                                      /* tp_str */
 401         PyObject_GenericGetAttr,                /* tp_getattro */
 402         0,                                      /* tp_setattro */
 403         0,                                      /* tp_as_buffer */
 404         Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
 405         0,                                      /* tp_doc */
 406         descr_traverse,                         /* tp_traverse */
 407         0,                                      /* tp_clear */
 408         0,                                      /* tp_richcompare */
 409         0,                                      /* tp_weaklistoffset */
 410         0,                                      /* tp_iter */
 411         0,                                      /* tp_iternext */
 412         0,                                      /* tp_methods */
 413         descr_members,                          /* tp_members */
 414         method_getset,                          /* tp_getset */
 415         0,                                      /* tp_base */
 416         0,                                      /* tp_dict */
 417         (descrgetfunc)method_get,               /* tp_descr_get */
 418         0,                                      /* tp_descr_set */
 419 };
 420
 421 /* This is for METH_CLASS in C, not for "f = classmethod(f)" in Python! */
 422 static PyTypeObject PyClassMethodDescr_Type = {
 423         PyVarObject_HEAD_INIT(&PyType_Type, 0)
 424         "classmethod_descriptor",
 425         sizeof(PyMethodDescrObject),
 426         0,
 427         (destructor)descr_dealloc,              /* tp_dealloc */
 428         0,                                      /* tp_print */
 429         0,                                      /* tp_getattr */
 430         0,                                      /* tp_setattr */
 431         0,                                      /* tp_compare */
 432         (reprfunc)method_repr,                  /* tp_repr */
 433         0,                                      /* tp_as_number */
 434         0,                                      /* tp_as_sequence */
 435         0,                                      /* tp_as_mapping */
 436         0,                                      /* tp_hash */
 437         (ternaryfunc)classmethoddescr_call,     /* tp_call */
 438         0,                                      /* tp_str */
 439         PyObject_GenericGetAttr,                /* tp_getattro */
 440         0,                                      /* tp_setattro */
 441         0,                                      /* tp_as_buffer */
 442         Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
 443         0,                                      /* tp_doc */
 444         descr_traverse,                         /* tp_traverse */
 445         0,                                      /* tp_clear */
 446         0,                                      /* tp_richcompare */
 447         0,                                      /* tp_weaklistoffset */
 448         0,                                      /* tp_iter */
 449         0,                                      /* tp_iternext */
 450         0,                                      /* tp_methods */
 451         descr_members,                          /* tp_members */
 452         method_getset,                          /* tp_getset */
 453         0,                                      /* tp_base */
 454         0,                                      /* tp_dict */
 455         (descrgetfunc)classmethod_get,          /* tp_descr_get */
 456         0,                                      /* tp_descr_set */
 457 };
 458
 459 PyTypeObject PyMemberDescr_Type = {
 460         PyVarObject_HEAD_INIT(&PyType_Type, 0)
 461         "member_descriptor",
 462         sizeof(PyMemberDescrObject),
 463         0,
 464         (destructor)descr_dealloc,              /* tp_dealloc */
 465         0,                                      /* tp_print */
 466         0,                                      /* tp_getattr */
 467         0,                                      /* tp_setattr */
 468         0,                                      /* tp_compare */
 469         (reprfunc)member_repr,                  /* tp_repr */
 470         0,                                      /* tp_as_number */
 471         0,                                      /* tp_as_sequence */
 472         0,                                      /* tp_as_mapping */
 473         0,                                      /* tp_hash */
 474         0,                                      /* tp_call */
 475         0,                                      /* tp_str */
 476         PyObject_GenericGetAttr,                /* tp_getattro */
 477         0,                                      /* tp_setattro */
 478         0,                                      /* tp_as_buffer */
 479         Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
 480         0,                                      /* tp_doc */
 481         descr_traverse,                         /* tp_traverse */
 482         0,                                      /* tp_clear */
 483         0,                                      /* tp_richcompare */
 484         0,                                      /* tp_weaklistoffset */
 485         0,                                      /* tp_iter */
 486         0,                                      /* tp_iternext */
 487         0,                                      /* tp_methods */
 488         descr_members,                          /* tp_members */
 489         member_getset,                          /* tp_getset */
 490         0,                                      /* tp_base */
 491         0,                                      /* tp_dict */
 492         (descrgetfunc)member_get,               /* tp_descr_get */
 493         (descrsetfunc)member_set,               /* tp_descr_set */
 494 };
 495
 496 PyTypeObject PyGetSetDescr_Type = {
 497         PyVarObject_HEAD_INIT(&PyType_Type, 0)
 498         "getset_descriptor",
 499         sizeof(PyGetSetDescrObject),
 500         0,
 501         (destructor)descr_dealloc,              /* tp_dealloc */
 502         0,                                      /* tp_print */
 503         0,                                      /* tp_getattr */
 504         0,                                      /* tp_setattr */
 505         0,                                      /* tp_compare */
 506         (reprfunc)getset_repr,                  /* tp_repr */
 507         0,                                      /* tp_as_number */
 508         0,                                      /* tp_as_sequence */
 509         0,                                      /* tp_as_mapping */
 510         0,                                      /* tp_hash */
 511         0,                                      /* tp_call */
 512         0,                                      /* tp_str */
 513         PyObject_GenericGetAttr,                /* tp_getattro */
 514         0,                                      /* tp_setattro */
 515         0,                                      /* tp_as_buffer */
 516         Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
 517         0,                                      /* tp_doc */
 518         descr_traverse,                         /* tp_traverse */
 519         0,                                      /* tp_clear */
 520         0,                                      /* tp_richcompare */
 521         0,                                      /* tp_weaklistoffset */
 522         0,                                      /* tp_iter */
 523         0,                                      /* tp_iternext */
 524         0,                                      /* tp_methods */
 525         descr_members,                          /* tp_members */
 526         getset_getset,                          /* tp_getset */
 527         0,                                      /* tp_base */
 528         0,                                      /* tp_dict */
 529         (descrgetfunc)getset_get,               /* tp_descr_get */
 530         (descrsetfunc)getset_set,               /* tp_descr_set */
 531 };
 532
 533 PyTypeObject PyWrapperDescr_Type = {
 534         PyVarObject_HEAD_INIT(&PyType_Type, 0)
 535         "wrapper_descriptor",
 536         sizeof(PyWrapperDescrObject),
 537         0,
 538         (destructor)descr_dealloc,              /* tp_dealloc */
 539         0,                                      /* tp_print */
 540         0,                                      /* tp_getattr */
 541         0,                                      /* tp_setattr */
 542         0,                                      /* tp_compare */
 543         (reprfunc)wrapperdescr_repr,            /* tp_repr */
 544         0,                                      /* tp_as_number */
 545         0,                                      /* tp_as_sequence */
 546         0,                                      /* tp_as_mapping */
 547         0,                                      /* tp_hash */
 548         (ternaryfunc)wrapperdescr_call,         /* tp_call */
 549         0,                                      /* tp_str */
 550         PyObject_GenericGetAttr,                /* tp_getattro */
 551         0,                                      /* tp_setattro */
 552         0,                                      /* tp_as_buffer */
 553         Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
 554         0,                                      /* tp_doc */
 555         descr_traverse,                         /* tp_traverse */
 556         0,                                      /* tp_clear */
 557         0,                                      /* tp_richcompare */
 558         0,                                      /* tp_weaklistoffset */
 559         0,                                      /* tp_iter */
 560         0,                                      /* tp_iternext */
 561         0,                                      /* tp_methods */
 562         descr_members,                          /* tp_members */
 563         wrapperdescr_getset,                    /* tp_getset */
 564         0,                                      /* tp_base */
 565         0,                                      /* tp_dict */
 566         (descrgetfunc)wrapperdescr_get,         /* tp_descr_get */
 567         0,                                      /* tp_descr_set */
 568 };
 569
 570 static PyDescrObject *
 571 descr_new(PyTypeObject *descrtype, PyTypeObject *type, const char *name)
 572 {
 573         PyDescrObject *descr;
 574
 575         descr = (PyDescrObject *)PyType_GenericAlloc(descrtype, 0);
 576         if (descr != NULL) {
 577                 Py_XINCREF(type);
 578                 descr->d_type = type;
 579                 descr->d_name = PyString_InternFromString(name);
 580                 if (descr->d_name == NULL) {
 581                         Py_DECREF(descr);
 582                         descr = NULL;
 583                 }
 584         }
 585         return descr;
 586 }
 587
 588 PyObject *
 589 PyDescr_NewMethod(PyTypeObject *type, PyMethodDef *method)
 590 {
 591         PyMethodDescrObject *descr;
 592
 593         descr = (PyMethodDescrObject *)descr_new(&PyMethodDescr_Type,
 594                                                  type, method->ml_name);
 595         if (descr != NULL)
 596                 descr->d_method = method;
 597         return (PyObject *)descr;
 598 }
 599
 600 PyObject *
 601 PyDescr_NewClassMethod(PyTypeObject *type, PyMethodDef *method)
 602 {
 603         PyMethodDescrObject *descr;
 604
 605         descr = (PyMethodDescrObject *)descr_new(&PyClassMethodDescr_Type,
 606                                                  type, method->ml_name);
 607         if (descr != NULL)
 608                 descr->d_method = method;
 609         return (PyObject *)descr;
 610 }
 611
 612 PyObject *
 613 PyDescr_NewMember(PyTypeObject *type, PyMemberDef *member)
 614 {
 615         PyMemberDescrObject *descr;
 616
 617         descr = (PyMemberDescrObject *)descr_new(&PyMemberDescr_Type,
 618                                                  type, member->name);
 619         if (descr != NULL)
 620                 descr->d_member = member;
 621         return (PyObject *)descr;
 622 }
 623
 624 PyObject *
 625 PyDescr_NewGetSet(PyTypeObject *type, PyGetSetDef *getset)
 626 {
 627         PyGetSetDescrObject *descr;
 628
 629         descr = (PyGetSetDescrObject *)descr_new(&PyGetSetDescr_Type,
 630                                                  type, getset->name);
 631         if (descr != NULL)
 632                 descr->d_getset = getset;
 633         return (PyObject *)descr;
 634 }
 635
 636 PyObject *
 637 PyDescr_NewWrapper(PyTypeObject *type, struct wrapperbase *base, void *wrapped)
 638 {
 639         PyWrapperDescrObject *descr;
 640
 641         descr = (PyWrapperDescrObject *)descr_new(&PyWrapperDescr_Type,
 642                                                  type, base->name);
 643         if (descr != NULL) {
 644                 descr->d_base = base;
 645                 descr->d_wrapped = wrapped;
 646         }
 647         return (PyObject *)descr;
 648 }
 649
 650
 651 /* --- Readonly proxy for dictionaries (actually any mapping) --- */
 652
 653 /* This has no reason to be in this file except that adding new files is a
 654    bit of a pain */
 655
 656 typedef struct {
 657         PyObject_HEAD
 658         PyObject *dict;
 659 } proxyobject;
 660
 661 static Py_ssize_t
 662 proxy_len(proxyobject *pp)
 663 {
 664         return PyObject_Size(pp->dict);
 665 }
 666
 667 static PyObject *
 668 proxy_getitem(proxyobject *pp, PyObject *key)
 669 {
 670         return PyObject_GetItem(pp->dict, key);
 671 }
 672
 673 static PyMappingMethods proxy_as_mapping = {
 674         (lenfunc)proxy_len,                     /* mp_length */
 675         (binaryfunc)proxy_getitem,              /* mp_subscript */
 676         0,                                      /* mp_ass_subscript */
 677 };
 678
 679 static int
 680 proxy_contains(proxyobject *pp, PyObject *key)
 681 {
 682         return PyDict_Contains(pp->dict, key);
 683 }
 684
 685 static PySequenceMethods proxy_as_sequence = {
 686         0,                                      /* sq_length */
 687         0,                                      /* sq_concat */
 688         0,                                      /* sq_repeat */
 689         0,                                      /* sq_item */
 690         0,                                      /* sq_slice */
 691         0,                                      /* sq_ass_item */
 692         0,                                      /* sq_ass_slice */
 693         (objobjproc)proxy_contains,             /* sq_contains */
 694         0,                                      /* sq_inplace_concat */
 695         0,                                      /* sq_inplace_repeat */
 696 };
 697
 698 static PyObject *
 699 proxy_has_key(proxyobject *pp, PyObject *key)
 700 {
 701         int res = PyDict_Contains(pp->dict, key);
 702         if (res < 0)
 703                 return NULL;
 704         return PyBool_FromLong(res);
 705 }
 706
 707 static PyObject *
 708 proxy_get(proxyobject *pp, PyObject *args)
 709 {
 710         PyObject *key, *def = Py_None;
 711
 712         if (!PyArg_UnpackTuple(args, "get", 1, 2, &key, &def))
 713                 return NULL;
 714         return PyObject_CallMethod(pp->dict, "get", "(OO)", key, def);
 715 }
 716
 717 static PyObject *
 718 proxy_keys(proxyobject *pp)
 719 {
 720         return PyMapping_Keys(pp->dict);
 721 }
 722
 723 static PyObject *
 724 proxy_values(proxyobject *pp)
 725 {
 726         return PyMapping_Values(pp->dict);
 727 }
 728
 729 static PyObject *
 730 proxy_items(proxyobject *pp)
 731 {
 732         return PyMapping_Items(pp->dict);
 733 }
 734
 735 static PyObject *
 736 proxy_iterkeys(proxyobject *pp)
 737 {
 738         return PyObject_CallMethod(pp->dict, "iterkeys", NULL);
 739 }
 740
 741 static PyObject *
 742 proxy_itervalues(proxyobject *pp)
 743 {
 744         return PyObject_CallMethod(pp->dict, "itervalues", NULL);
 745 }
 746
 747 static PyObject *
 748 proxy_iteritems(proxyobject *pp)
 749 {
 750         return PyObject_CallMethod(pp->dict, "iteritems", NULL);
 751 }
 752 static PyObject *
 753 proxy_copy(proxyobject *pp)
 754 {
 755         return PyObject_CallMethod(pp->dict, "copy", NULL);
 756 }
 757
 758 static PyMethodDef proxy_methods[] = {
 759         {"has_key",   (PyCFunction)proxy_has_key,    METH_O,
 760          PyDoc_STR("D.has_key(k) -> True if D has a key k, else False")},
 761         {"get",       (PyCFunction)proxy_get,        METH_VARARGS,
 762          PyDoc_STR("D.get(k[,d]) -> D[k] if D.has_key(k), else d."
 763                                         "  d defaults to None.")},
 764         {"keys",      (PyCFunction)proxy_keys,       METH_NOARGS,
 765          PyDoc_STR("D.keys() -> list of D's keys")},
 766         {"values",    (PyCFunction)proxy_values,     METH_NOARGS,
 767          PyDoc_STR("D.values() -> list of D's values")},
 768         {"items",     (PyCFunction)proxy_items,      METH_NOARGS,
 769          PyDoc_STR("D.items() -> list of D's (key, value) pairs, as 2-tuples")},
 770         {"iterkeys",  (PyCFunction)proxy_iterkeys,   METH_NOARGS,
 771          PyDoc_STR("D.iterkeys() -> an iterator over the keys of D")},
 772         {"itervalues",(PyCFunction)proxy_itervalues, METH_NOARGS,
 773          PyDoc_STR("D.itervalues() -> an iterator over the values of D")},
 774         {"iteritems", (PyCFunction)proxy_iteritems,  METH_NOARGS,
 775          PyDoc_STR("D.iteritems() ->"
 776                    " an iterator over the (key, value) items of D")},
 777         {"copy",      (PyCFunction)proxy_copy,       METH_NOARGS,
 778          PyDoc_STR("D.copy() -> a shallow copy of D")},
 779         {0}
 780 };
 781
 782 static void
 783 proxy_dealloc(proxyobject *pp)
 784 {
 785         _PyObject_GC_UNTRACK(pp);
 786         Py_DECREF(pp->dict);
 787         PyObject_GC_Del(pp);
 788 }
 789
 790 static PyObject *
 791 proxy_getiter(proxyobject *pp)
 792 {
 793         return PyObject_GetIter(pp->dict);
 794 }
 795
 796 static PyObject *
 797 proxy_str(proxyobject *pp)
 798 {
 799         return PyObject_Str(pp->dict);
 800 }
 801
 802 static int
 803 proxy_traverse(PyObject *self, visitproc visit, void *arg)
 804 {
 805         proxyobject *pp = (proxyobject *)self;
 806         Py_VISIT(pp->dict);
 807         return 0;
 808 }
 809
 810 static int
 811 proxy_compare(proxyobject *v, PyObject *w)
 812 {
 813         return PyObject_Compare(v->dict, w);
 814 }
 815
 816 static PyObject *
 817 proxy_richcompare(proxyobject *v, PyObject *w, int op)
 818 {
 819         return PyObject_RichCompare(v->dict, w, op);
 820 }
 821
 822 PyTypeObject PyDictProxy_Type = {
 823         PyVarObject_HEAD_INIT(&PyType_Type, 0)
 824         "dictproxy",                            /* tp_name */
 825         sizeof(proxyobject),                    /* tp_basicsize */
 826         0,                                      /* tp_itemsize */
 827         /* methods */
 828         (destructor)proxy_dealloc,              /* tp_dealloc */
 829         0,                                      /* tp_print */
 830         0,                                      /* tp_getattr */
 831         0,                                      /* tp_setattr */
 832         (cmpfunc)proxy_compare,                 /* tp_compare */
 833         0,                                      /* tp_repr */
 834         0,                                      /* tp_as_number */
 835         &proxy_as_sequence,                     /* tp_as_sequence */
 836         &proxy_as_mapping,                      /* tp_as_mapping */
 837         0,                                      /* tp_hash */
 838         0,                                      /* tp_call */
 839         (reprfunc)proxy_str,                    /* tp_str */
 840         PyObject_GenericGetAttr,                /* tp_getattro */
 841         0,                                      /* tp_setattro */
 842         0,                                      /* tp_as_buffer */
 843         Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
 844         0,                                      /* tp_doc */
 845         proxy_traverse,                         /* tp_traverse */
 846         0,                                      /* tp_clear */
 847         (richcmpfunc)proxy_richcompare,         /* tp_richcompare */
 848         0,                                      /* tp_weaklistoffset */
 849         (getiterfunc)proxy_getiter,             /* tp_iter */
 850         0,                                      /* tp_iternext */
 851         proxy_methods,                          /* tp_methods */
 852         0,                                      /* tp_members */
 853         0,                                      /* tp_getset */
 854         0,                                      /* tp_base */
 855         0,                                      /* tp_dict */
 856         0,                                      /* tp_descr_get */
 857         0,                                      /* tp_descr_set */
 858 };
 859
 860 PyObject *
 861 PyDictProxy_New(PyObject *dict)
 862 {
 863         proxyobject *pp;
 864
 865         pp = PyObject_GC_New(proxyobject, &PyDictProxy_Type);
 866         if (pp != NULL) {
 867                 Py_INCREF(dict);
 868                 pp->dict = dict;
 869                 _PyObject_GC_TRACK(pp);
 870         }
 871         return (PyObject *)pp;
 872 }
 873
 874
 875 /* --- Wrapper object for "slot" methods --- */
 876
 877 /* This has no reason to be in this file except that adding new files is a
 878    bit of a pain */
 879
 880 typedef struct {
 881         PyObject_HEAD
 882         PyWrapperDescrObject *descr;
 883         PyObject *self;
 884 } wrapperobject;
 885
 886 static void
 887 wrapper_dealloc(wrapperobject *wp)
 888 {
 889         PyObject_GC_UnTrack(wp);
 890         Py_TRASHCAN_SAFE_BEGIN(wp)
 891         Py_XDECREF(wp->descr);
 892         Py_XDECREF(wp->self);
 893         PyObject_GC_Del(wp);
 894         Py_TRASHCAN_SAFE_END(wp)
 895 }
 896
 897 static int
 898 wrapper_compare(wrapperobject *a, wrapperobject *b)
 899 {
 900         if (a->descr == b->descr)
 901                 return PyObject_Compare(a->self, b->self);
 902         else
 903                 return (a->descr < b->descr) ? -1 : 1;
 904 }
 905
 906 static long
 907 wrapper_hash(wrapperobject *wp)
 908 {
 909         int x, y;
 910         x = _Py_HashPointer(wp->descr);
 911         if (x == -1)
 912                 return -1;
 913         y = PyObject_Hash(wp->self);
 914         if (y == -1)
 915                 return -1;
 916         x = x ^ y;
 917         if (x == -1)
 918                 x = -2;
 919         return x;
 920 }
 921
 922 static PyObject *
 923 wrapper_repr(wrapperobject *wp)
 924 {
 925         return PyString_FromFormat("<method-wrapper '%s' of %s object at %p>",
 926                                    wp->descr->d_base->name,
 927                                    wp->self->ob_type->tp_name,
 928                                    wp->self);
 929 }
 930
 931 static PyMemberDef wrapper_members[] = {
 932         {"__self__", T_OBJECT, offsetof(wrapperobject, self), READONLY},
 933         {0}
 934 };
 935
 936 static PyObject *
 937 wrapper_objclass(wrapperobject *wp)
 938 {
 939         PyObject *c = (PyObject *)wp->descr->d_type;
 940
 941         Py_INCREF(c);
 942         return c;
 943 }
 944
 945 static PyObject *
 946 wrapper_name(wrapperobject *wp)
 947 {
 948         char *s = wp->descr->d_base->name;
 949
 950         return PyString_FromString(s);
 951 }
 952
 953 static PyObject *
 954 wrapper_doc(wrapperobject *wp)
 955 {
 956         char *s = wp->descr->d_base->doc;
 957
 958         if (s == NULL) {
 959                 Py_INCREF(Py_None);
 960                 return Py_None;
 961         }
 962         else {
 963                 return PyString_FromString(s);
 964         }
 965 }
 966
 967 static PyGetSetDef wrapper_getsets[] = {
 968         {"__objclass__", (getter)wrapper_objclass},
 969         {"__name__", (getter)wrapper_name},
 970         {"__doc__", (getter)wrapper_doc},
 971         {0}
 972 };
 973
 974 static PyObject *
 975 wrapper_call(wrapperobject *wp, PyObject *args, PyObject *kwds)
 976 {
 977         wrapperfunc wrapper = wp->descr->d_base->wrapper;
 978         PyObject *self = wp->self;
 979
 980         if (wp->descr->d_base->flags & PyWrapperFlag_KEYWORDS) {
 981                 wrapperfunc_kwds wk = (wrapperfunc_kwds)wrapper;
 982                 return (*wk)(self, args, wp->descr->d_wrapped, kwds);
 983         }
 984
 985         if (kwds != NULL && (!PyDict_Check(kwds) || PyDict_Size(kwds) != 0)) {
 986                 PyErr_Format(PyExc_TypeError,
 987                              "wrapper %s doesn't take keyword arguments",
 988                              wp->descr->d_base->name);
 989                 return NULL;
 990         }
 991         return (*wrapper)(self, args, wp->descr->d_wrapped);
 992 }
 993
 994 static int
 995 wrapper_traverse(PyObject *self, visitproc visit, void *arg)
 996 {
 997         wrapperobject *wp = (wrapperobject *)self;
 998         Py_VISIT(wp->descr);
 999         Py_VISIT(wp->self);
1000         return 0;
1001 }
1002
1003 static PyTypeObject wrappertype = {
1004         PyVarObject_HEAD_INIT(&PyType_Type, 0)
1005         "method-wrapper",                       /* tp_name */
1006         sizeof(wrapperobject),                  /* tp_basicsize */
1007         0,                                      /* tp_itemsize */
1008         /* methods */
1009         (destructor)wrapper_dealloc,            /* tp_dealloc */
1010         0,                                      /* tp_print */
1011         0,                                      /* tp_getattr */
1012         0,                                      /* tp_setattr */
1013         (cmpfunc)wrapper_compare,               /* tp_compare */
1014         (reprfunc)wrapper_repr,                 /* tp_repr */
1015         0,                                      /* tp_as_number */
1016         0,                                      /* tp_as_sequence */
1017         0,                                      /* tp_as_mapping */
1018         (hashfunc)wrapper_hash,                 /* tp_hash */
1019         (ternaryfunc)wrapper_call,              /* tp_call */
1020         0,                                      /* tp_str */
1021         PyObject_GenericGetAttr,                /* tp_getattro */
1022         0,                                      /* tp_setattro */
1023         0,                                      /* tp_as_buffer */
1024         Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
1025         0,                                      /* tp_doc */
1026         wrapper_traverse,                       /* tp_traverse */
1027         0,                                      /* tp_clear */
1028         0,                                      /* tp_richcompare */
1029         0,                                      /* tp_weaklistoffset */
1030         0,                                      /* tp_iter */
1031         0,                                      /* tp_iternext */
1032         0,                                      /* tp_methods */
1033         wrapper_members,                        /* tp_members */
1034         wrapper_getsets,                        /* tp_getset */
1035         0,                                      /* tp_base */
1036         0,                                      /* tp_dict */
1037         0,                                      /* tp_descr_get */
1038         0,                                      /* tp_descr_set */
1039 };
1040
1041 PyObject *
1042 PyWrapper_New(PyObject *d, PyObject *self)
1043 {
1044         wrapperobject *wp;
1045         PyWrapperDescrObject *descr;
1046
1047         assert(PyObject_TypeCheck(d, &PyWrapperDescr_Type));
1048         descr = (PyWrapperDescrObject *)d;
1049         assert(PyObject_IsInstance(self, (PyObject *)(descr->d_type)));
1050
1051         wp = PyObject_GC_New(wrapperobject, &wrappertype);
1052         if (wp != NULL) {
1053                 Py_INCREF(descr);
1054                 wp->descr = descr;
1055                 Py_INCREF(self);
1056                 wp->self = self;
1057                 _PyObject_GC_TRACK(wp);
1058         }
1059         return (PyObject *)wp;
1060 }
1061
1062
1063 /* A built-in 'property' type */
1064
1065 /*
1066     class property(object):
1067
1068         def __init__(self, fget=None, fset=None, fdel=None, doc=None):
1069             if doc is None and fget is not None and hasattr(fget, "__doc__"):
1070                 doc = fget.__doc__
1071             self.__get = fget
1072             self.__set = fset
1073             self.__del = fdel
1074             self.__doc__ = doc
1075
1076         def __get__(self, inst, type=None):
1077             if inst is None:
1078                 return self
1079             if self.__get is None:
1080                 raise AttributeError, "unreadable attribute"
1081             return self.__get(inst)
1082
1083         def __set__(self, inst, value):
1084             if self.__set is None:
1085                 raise AttributeError, "can't set attribute"
1086             return self.__set(inst, value)
1087
1088         def __delete__(self, inst):
1089             if self.__del is None:
1090                 raise AttributeError, "can't delete attribute"
1091             return self.__del(inst)
1092
1093 */
1094
1095 typedef struct {
1096         PyObject_HEAD
1097         PyObject *prop_get;
1098         PyObject *prop_set;
1099         PyObject *prop_del;
1100         PyObject *prop_doc;
1101         int getter_doc;
1102 } propertyobject;
1103
1104 static PyObject * property_copy(PyObject *, PyObject *, PyObject *,
1105                                   PyObject *, PyObject *);
1106
1107 static PyMemberDef property_members[] = {
1108         {"fget", T_OBJECT, offsetof(propertyobject, prop_get), READONLY},
1109         {"fset", T_OBJECT, offsetof(propertyobject, prop_set), READONLY},
1110         {"fdel", T_OBJECT, offsetof(propertyobject, prop_del), READONLY},
1111         {"__doc__",  T_OBJECT, offsetof(propertyobject, prop_doc), READONLY},
1112         {0}
1113 };
1114
1115
1116 PyDoc_STRVAR(getter_doc,
1117              "Descriptor to change the getter on a property.");
1118
1119 static PyObject *
1120 property_getter(PyObject *self, PyObject *getter)
1121 {
1122         return property_copy(self, getter, NULL, NULL, NULL);
1123 }
1124
1125
1126 PyDoc_STRVAR(setter_doc,
1127              "Descriptor to change the setter on a property.");
1128
1129 static PyObject *
1130 property_setter(PyObject *self, PyObject *setter)
1131 {
1132         return property_copy(self, NULL, setter, NULL, NULL);
1133 }
1134
1135
1136 PyDoc_STRVAR(deleter_doc,
1137              "Descriptor to change the deleter on a property.");
1138
1139 static PyObject *
1140 property_deleter(PyObject *self, PyObject *deleter)
1141 {
1142         return property_copy(self, NULL, NULL, deleter, NULL);
1143 }
1144
1145
1146 static PyMethodDef property_methods[] = {
1147         {"getter", property_getter, METH_O, getter_doc},
1148         {"setter", property_setter, METH_O, setter_doc},
1149         {"deleter", property_deleter, METH_O, deleter_doc},
1150         {0}
1151 };
1152
1153
1154 static void
1155 property_dealloc(PyObject *self)
1156 {
1157         propertyobject *gs = (propertyobject *)self;
1158
1159         _PyObject_GC_UNTRACK(self);
1160         Py_XDECREF(gs->prop_get);
1161         Py_XDECREF(gs->prop_set);
1162         Py_XDECREF(gs->prop_del);
1163         Py_XDECREF(gs->prop_doc);
1164         self->ob_type->tp_free(self);
1165 }
1166
1167 static PyObject *
1168 property_descr_get(PyObject *self, PyObject *obj, PyObject *type)
1169 {
1170         propertyobject *gs = (propertyobject *)self;
1171
1172         if (obj == NULL || obj == Py_None) {
1173                 Py_INCREF(self);
1174                 return self;
1175         }
1176         if (gs->prop_get == NULL) {
1177                 PyErr_SetString(PyExc_AttributeError, "unreadable attribute");
1178                 return NULL;
1179         }
1180         return PyObject_CallFunction(gs->prop_get, "(O)", obj);
1181 }
1182
1183 static int
1184 property_descr_set(PyObject *self, PyObject *obj, PyObject *value)
1185 {
1186         propertyobject *gs = (propertyobject *)self;
1187         PyObject *func, *res;
1188
1189         if (value == NULL)
1190                 func = gs->prop_del;
1191         else
1192                 func = gs->prop_set;
1193         if (func == NULL) {
1194                 PyErr_SetString(PyExc_AttributeError,
1195                                 value == NULL ?
1196                                 "can't delete attribute" :
1197                                 "can't set attribute");
1198                 return -1;
1199         }
1200         if (value == NULL)
1201                 res = PyObject_CallFunction(func, "(O)", obj);
1202         else
1203                 res = PyObject_CallFunction(func, "(OO)", obj, value);
1204         if (res == NULL)
1205                 return -1;
1206         Py_DECREF(res);
1207         return 0;
1208 }
1209
1210 static PyObject *
1211 property_copy(PyObject *old, PyObject *get, PyObject *set, PyObject *del,
1212                 PyObject *doc)
1213 {
1214         propertyobject *pold = (propertyobject *)old;
1215         PyObject *new, *type;
1216
1217         type = PyObject_Type(old);
1218         if (type == NULL)
1219                 return NULL;
1220
1221         if (get == NULL || get == Py_None) {
1222                 Py_XDECREF(get);
1223                 get = pold->prop_get ? pold->prop_get : Py_None;
1224         }
1225         if (set == NULL || set == Py_None) {
1226                 Py_XDECREF(set);
1227                 set = pold->prop_set ? pold->prop_set : Py_None;
1228         }
1229         if (del == NULL || del == Py_None) {
1230                 Py_XDECREF(del);
1231                 del = pold->prop_del ? pold->prop_del : Py_None;
1232         }
1233         if (doc == NULL || doc == Py_None) {
1234                 Py_XDECREF(doc);
1235                 if (pold->getter_doc && get != Py_None) {
1236                         /* make _init use __doc__ from getter */
1237                         doc = Py_None;
1238                 }
1239                 else {
1240                         doc = pold->prop_doc ? pold->prop_doc : Py_None;
1241                 }
1242         }
1243
1244         new =  PyObject_CallFunction(type, "OOOO", get, set, del, doc);
1245         Py_DECREF(type);
1246         if (new == NULL)
1247                 return NULL;
1248         return new;
1249 }
1250
1251 static int
1252 property_init(PyObject *self, PyObject *args, PyObject *kwds)
1253 {
1254         PyObject *get = NULL, *set = NULL, *del = NULL, *doc = NULL;
1255         static char *kwlist[] = {"fget", "fset", "fdel", "doc", 0};
1256         propertyobject *prop = (propertyobject *)self;
1257
1258         if (!PyArg_ParseTupleAndKeywords(args, kwds, "|OOOO:property",
1259                                          kwlist, &get, &set, &del, &doc))
1260                 return -1;
1261
1262         if (get == Py_None)
1263                 get = NULL;
1264         if (set == Py_None)
1265                 set = NULL;
1266         if (del == Py_None)
1267                 del = NULL;
1268
1269         Py_XINCREF(get);
1270         Py_XINCREF(set);
1271         Py_XINCREF(del);
1272         Py_XINCREF(doc);
1273
1274         prop->prop_get = get;
1275         prop->prop_set = set;
1276         prop->prop_del = del;
1277         prop->prop_doc = doc;
1278         prop->getter_doc = 0;
1279
1280         /* if no docstring given and the getter has one, use that one */
1281         if ((doc == NULL || doc == Py_None) && get != NULL) {
1282                 PyObject *get_doc = PyObject_GetAttrString(get, "__doc__");
1283                 if (get_doc != NULL) {
1284                         /* get_doc already INCREF'd by GetAttr */
1285                         if (Py_TYPE(self)==&PyProperty_Type) {
1286                                 Py_XDECREF(prop->prop_doc);
1287                                 prop->prop_doc = get_doc;
1288                         } else {
1289                                 /* Put __doc__ in dict of the subclass instance instead,
1290                                 otherwise it gets shadowed by class's __doc__. */
1291                                 if (PyObject_SetAttrString(self, "__doc__", get_doc) != 0)
1292                                 {
1293                                         /* DECREF for props handled by _dealloc */
1294                                         Py_DECREF(get_doc);
1295                                         return -1;
1296                                 }
1297                                 Py_DECREF(get_doc);
1298                         }
1299                         prop->getter_doc = 1;
1300                 } else {
1301                         PyErr_Clear();
1302                 }
1303         }
1304
1305         return 0;
1306 }
1307
1308 PyDoc_STRVAR(property_doc,
1309 "property(fget=None, fset=None, fdel=None, doc=None) -> property attribute\n"
1310 "\n"
1311 "fget is a function to be used for getting an attribute value, and likewise\n"
1312 "fset is a function for setting, and fdel a function for del'ing, an\n"
1313 "attribute.  Typical use is to define a managed attribute x:\n"
1314 "class C(object):\n"
1315 "    def getx(self): return self._x\n"
1316 "    def setx(self, value): self._x = value\n"
1317 "    def delx(self): del self._x\n"
1318 "    x = property(getx, setx, delx, \"I'm the 'x' property.\")\n"
1319 "\n"
1320 "Decorators make defining new properties or modifying existing ones easy:\n"
1321 "class C(object):\n"
1322 "    @property\n"
1323 "    def x(self): return self._x\n"
1324 "    @x.setter\n"
1325 "    def x(self, value): self._x = value\n"
1326 "    @x.deleter\n"
1327 "    def x(self): del self._x\n"
1328 );
1329
1330 static int
1331 property_traverse(PyObject *self, visitproc visit, void *arg)
1332 {
1333         propertyobject *pp = (propertyobject *)self;
1334         Py_VISIT(pp->prop_get);
1335         Py_VISIT(pp->prop_set);
1336         Py_VISIT(pp->prop_del);
1337         Py_VISIT(pp->prop_doc);
1338         return 0;
1339 }
1340
1341 PyTypeObject PyProperty_Type = {
1342         PyVarObject_HEAD_INIT(&PyType_Type, 0)
1343         "property",                             /* tp_name */
1344         sizeof(propertyobject),                 /* tp_basicsize */
1345         0,                                      /* tp_itemsize */
1346         /* methods */
1347         property_dealloc,                       /* tp_dealloc */
1348         0,                                      /* tp_print */
1349         0,                                      /* tp_getattr */
1350         0,                                      /* tp_setattr */
1351         0,                                      /* tp_compare */
1352         0,                                      /* tp_repr */
1353         0,                                      /* tp_as_number */
1354         0,                                      /* tp_as_sequence */
1355         0,                                      /* tp_as_mapping */
1356         0,                                      /* tp_hash */
1357         0,                                      /* tp_call */
1358         0,                                      /* tp_str */
1359         PyObject_GenericGetAttr,                /* tp_getattro */
1360         0,                                      /* tp_setattro */
1361         0,                                      /* tp_as_buffer */
1362         Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
1363                 Py_TPFLAGS_BASETYPE,            /* tp_flags */
1364         property_doc,                           /* tp_doc */
1365         property_traverse,                      /* tp_traverse */
1366         0,                                      /* tp_clear */
1367         0,                                      /* tp_richcompare */
1368         0,                                      /* tp_weaklistoffset */
1369         0,                                      /* tp_iter */
1370         0,                                      /* tp_iternext */
1371         property_methods,                       /* tp_methods */
1372         property_members,                       /* tp_members */
1373         0,                                      /* tp_getset */
1374         0,                                      /* tp_base */
1375         0,                                      /* tp_dict */
1376         property_descr_get,                     /* tp_descr_get */
1377         property_descr_set,                     /* tp_descr_set */
1378         0,                                      /* tp_dictoffset */
1379         property_init,                          /* tp_init */
1380         PyType_GenericAlloc,                    /* tp_alloc */
1381         PyType_GenericNew,                      /* tp_new */
1382         PyObject_GC_Del,                        /* tp_free */
1383 };