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[python.git] / Include / object.h
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1 #ifndef Py_OBJECT_H
2 #define Py_OBJECT_H
3 #ifdef __cplusplus
4 extern "C" {
5 #endif
8 /* Object and type object interface */
11 Objects are structures allocated on the heap. Special rules apply to
12 the use of objects to ensure they are properly garbage-collected.
13 Objects are never allocated statically or on the stack; they must be
14 accessed through special macros and functions only. (Type objects are
15 exceptions to the first rule; the standard types are represented by
16 statically initialized type objects, although work on type/class unification
17 for Python 2.2 made it possible to have heap-allocated type objects too).
19 An object has a 'reference count' that is increased or decreased when a
20 pointer to the object is copied or deleted; when the reference count
21 reaches zero there are no references to the object left and it can be
22 removed from the heap.
24 An object has a 'type' that determines what it represents and what kind
25 of data it contains. An object's type is fixed when it is created.
26 Types themselves are represented as objects; an object contains a
27 pointer to the corresponding type object. The type itself has a type
28 pointer pointing to the object representing the type 'type', which
29 contains a pointer to itself!).
31 Objects do not float around in memory; once allocated an object keeps
32 the same size and address. Objects that must hold variable-size data
33 can contain pointers to variable-size parts of the object. Not all
34 objects of the same type have the same size; but the size cannot change
35 after allocation. (These restrictions are made so a reference to an
36 object can be simply a pointer -- moving an object would require
37 updating all the pointers, and changing an object's size would require
38 moving it if there was another object right next to it.)
40 Objects are always accessed through pointers of the type 'PyObject *'.
41 The type 'PyObject' is a structure that only contains the reference count
42 and the type pointer. The actual memory allocated for an object
43 contains other data that can only be accessed after casting the pointer
44 to a pointer to a longer structure type. This longer type must start
45 with the reference count and type fields; the macro PyObject_HEAD should be
46 used for this (to accommodate for future changes). The implementation
47 of a particular object type can cast the object pointer to the proper
48 type and back.
50 A standard interface exists for objects that contain an array of items
51 whose size is determined when the object is allocated.
54 /* Py_DEBUG implies Py_TRACE_REFS. */
55 #if defined(Py_DEBUG) && !defined(Py_TRACE_REFS)
56 #define Py_TRACE_REFS
57 #endif
59 /* Py_TRACE_REFS implies Py_REF_DEBUG. */
60 #if defined(Py_TRACE_REFS) && !defined(Py_REF_DEBUG)
61 #define Py_REF_DEBUG
62 #endif
64 #ifdef Py_TRACE_REFS
65 /* Define pointers to support a doubly-linked list of all live heap objects. */
66 #define _PyObject_HEAD_EXTRA \
67 struct _object *_ob_next; \
68 struct _object *_ob_prev;
70 #define _PyObject_EXTRA_INIT 0, 0,
72 #else
73 #define _PyObject_HEAD_EXTRA
74 #define _PyObject_EXTRA_INIT
75 #endif
77 /* PyObject_HEAD defines the initial segment of every PyObject. */
78 #define PyObject_HEAD \
79 _PyObject_HEAD_EXTRA \
80 Py_ssize_t ob_refcnt; \
81 struct _typeobject *ob_type;
83 #define PyObject_HEAD_INIT(type) \
84 _PyObject_EXTRA_INIT \
85 1, type,
87 #define PyVarObject_HEAD_INIT(type, size) \
88 PyObject_HEAD_INIT(type) size,
90 /* PyObject_VAR_HEAD defines the initial segment of all variable-size
91 * container objects. These end with a declaration of an array with 1
92 * element, but enough space is malloc'ed so that the array actually
93 * has room for ob_size elements. Note that ob_size is an element count,
94 * not necessarily a byte count.
96 #define PyObject_VAR_HEAD \
97 PyObject_HEAD \
98 Py_ssize_t ob_size; /* Number of items in variable part */
99 #define Py_INVALID_SIZE (Py_ssize_t)-1
101 /* Nothing is actually declared to be a PyObject, but every pointer to
102 * a Python object can be cast to a PyObject*. This is inheritance built
103 * by hand. Similarly every pointer to a variable-size Python object can,
104 * in addition, be cast to PyVarObject*.
106 typedef struct _object {
107 PyObject_HEAD
108 } PyObject;
110 typedef struct {
111 PyObject_VAR_HEAD
112 } PyVarObject;
114 #define Py_REFCNT(ob) (((PyObject*)(ob))->ob_refcnt)
115 #define Py_TYPE(ob) (((PyObject*)(ob))->ob_type)
116 #define Py_SIZE(ob) (((PyVarObject*)(ob))->ob_size)
119 Type objects contain a string containing the type name (to help somewhat
120 in debugging), the allocation parameters (see PyObject_New() and
121 PyObject_NewVar()),
122 and methods for accessing objects of the type. Methods are optional, a
123 nil pointer meaning that particular kind of access is not available for
124 this type. The Py_DECREF() macro uses the tp_dealloc method without
125 checking for a nil pointer; it should always be implemented except if
126 the implementation can guarantee that the reference count will never
127 reach zero (e.g., for statically allocated type objects).
129 NB: the methods for certain type groups are now contained in separate
130 method blocks.
133 typedef PyObject * (*unaryfunc)(PyObject *);
134 typedef PyObject * (*binaryfunc)(PyObject *, PyObject *);
135 typedef PyObject * (*ternaryfunc)(PyObject *, PyObject *, PyObject *);
136 typedef int (*inquiry)(PyObject *);
137 typedef Py_ssize_t (*lenfunc)(PyObject *);
138 typedef int (*coercion)(PyObject **, PyObject **);
139 typedef PyObject *(*intargfunc)(PyObject *, int) Py_DEPRECATED(2.5);
140 typedef PyObject *(*intintargfunc)(PyObject *, int, int) Py_DEPRECATED(2.5);
141 typedef PyObject *(*ssizeargfunc)(PyObject *, Py_ssize_t);
142 typedef PyObject *(*ssizessizeargfunc)(PyObject *, Py_ssize_t, Py_ssize_t);
143 typedef int(*intobjargproc)(PyObject *, int, PyObject *);
144 typedef int(*intintobjargproc)(PyObject *, int, int, PyObject *);
145 typedef int(*ssizeobjargproc)(PyObject *, Py_ssize_t, PyObject *);
146 typedef int(*ssizessizeobjargproc)(PyObject *, Py_ssize_t, Py_ssize_t, PyObject *);
147 typedef int(*objobjargproc)(PyObject *, PyObject *, PyObject *);
151 /* int-based buffer interface */
152 typedef int (*getreadbufferproc)(PyObject *, int, void **);
153 typedef int (*getwritebufferproc)(PyObject *, int, void **);
154 typedef int (*getsegcountproc)(PyObject *, int *);
155 typedef int (*getcharbufferproc)(PyObject *, int, char **);
156 /* ssize_t-based buffer interface */
157 typedef Py_ssize_t (*readbufferproc)(PyObject *, Py_ssize_t, void **);
158 typedef Py_ssize_t (*writebufferproc)(PyObject *, Py_ssize_t, void **);
159 typedef Py_ssize_t (*segcountproc)(PyObject *, Py_ssize_t *);
160 typedef Py_ssize_t (*charbufferproc)(PyObject *, Py_ssize_t, char **);
162 /* Py3k buffer interface */
164 typedef struct bufferinfo {
165 void *buf;
166 PyObject *obj; /* borrowed reference */
167 Py_ssize_t len;
168 Py_ssize_t itemsize; /* This is Py_ssize_t so it can be
169 pointed to by strides in simple case.*/
170 int readonly;
171 int ndim;
172 char *format;
173 Py_ssize_t *shape;
174 Py_ssize_t *strides;
175 Py_ssize_t *suboffsets;
176 void *internal;
177 } Py_buffer;
179 typedef int (*getbufferproc)(PyObject *, Py_buffer *, int);
180 typedef void (*releasebufferproc)(PyObject *, Py_buffer *);
182 /* Flags for getting buffers */
183 #define PyBUF_SIMPLE 0
184 #define PyBUF_WRITABLE 0x0001
185 /* we used to include an E, backwards compatible alias */
186 #define PyBUF_WRITEABLE PyBUF_WRITABLE
187 #define PyBUF_FORMAT 0x0004
188 #define PyBUF_ND 0x0008
189 #define PyBUF_STRIDES (0x0010 | PyBUF_ND)
190 #define PyBUF_C_CONTIGUOUS (0x0020 | PyBUF_STRIDES)
191 #define PyBUF_F_CONTIGUOUS (0x0040 | PyBUF_STRIDES)
192 #define PyBUF_ANY_CONTIGUOUS (0x0080 | PyBUF_STRIDES)
193 #define PyBUF_INDIRECT (0x0100 | PyBUF_STRIDES)
195 #define PyBUF_CONTIG (PyBUF_ND | PyBUF_WRITABLE)
196 #define PyBUF_CONTIG_RO (PyBUF_ND)
198 #define PyBUF_STRIDED (PyBUF_STRIDES | PyBUF_WRITABLE)
199 #define PyBUF_STRIDED_RO (PyBUF_STRIDES)
201 #define PyBUF_RECORDS (PyBUF_STRIDES | PyBUF_WRITABLE | PyBUF_FORMAT)
202 #define PyBUF_RECORDS_RO (PyBUF_STRIDES | PyBUF_FORMAT)
204 #define PyBUF_FULL (PyBUF_INDIRECT | PyBUF_WRITABLE | PyBUF_FORMAT)
205 #define PyBUF_FULL_RO (PyBUF_INDIRECT | PyBUF_FORMAT)
208 #define PyBUF_READ 0x100
209 #define PyBUF_WRITE 0x200
210 #define PyBUF_SHADOW 0x400
211 /* end Py3k buffer interface */
213 typedef int (*objobjproc)(PyObject *, PyObject *);
214 typedef int (*visitproc)(PyObject *, void *);
215 typedef int (*traverseproc)(PyObject *, visitproc, void *);
217 typedef struct {
218 /* For numbers without flag bit Py_TPFLAGS_CHECKTYPES set, all
219 arguments are guaranteed to be of the object's type (modulo
220 coercion hacks -- i.e. if the type's coercion function
221 returns other types, then these are allowed as well). Numbers that
222 have the Py_TPFLAGS_CHECKTYPES flag bit set should check *both*
223 arguments for proper type and implement the necessary conversions
224 in the slot functions themselves. */
226 binaryfunc nb_add;
227 binaryfunc nb_subtract;
228 binaryfunc nb_multiply;
229 binaryfunc nb_divide;
230 binaryfunc nb_remainder;
231 binaryfunc nb_divmod;
232 ternaryfunc nb_power;
233 unaryfunc nb_negative;
234 unaryfunc nb_positive;
235 unaryfunc nb_absolute;
236 inquiry nb_nonzero;
237 unaryfunc nb_invert;
238 binaryfunc nb_lshift;
239 binaryfunc nb_rshift;
240 binaryfunc nb_and;
241 binaryfunc nb_xor;
242 binaryfunc nb_or;
243 coercion nb_coerce;
244 unaryfunc nb_int;
245 unaryfunc nb_long;
246 unaryfunc nb_float;
247 unaryfunc nb_oct;
248 unaryfunc nb_hex;
249 /* Added in release 2.0 */
250 binaryfunc nb_inplace_add;
251 binaryfunc nb_inplace_subtract;
252 binaryfunc nb_inplace_multiply;
253 binaryfunc nb_inplace_divide;
254 binaryfunc nb_inplace_remainder;
255 ternaryfunc nb_inplace_power;
256 binaryfunc nb_inplace_lshift;
257 binaryfunc nb_inplace_rshift;
258 binaryfunc nb_inplace_and;
259 binaryfunc nb_inplace_xor;
260 binaryfunc nb_inplace_or;
262 /* Added in release 2.2 */
263 /* The following require the Py_TPFLAGS_HAVE_CLASS flag */
264 binaryfunc nb_floor_divide;
265 binaryfunc nb_true_divide;
266 binaryfunc nb_inplace_floor_divide;
267 binaryfunc nb_inplace_true_divide;
269 /* Added in release 2.5 */
270 unaryfunc nb_index;
271 } PyNumberMethods;
273 typedef struct {
274 lenfunc sq_length;
275 binaryfunc sq_concat;
276 ssizeargfunc sq_repeat;
277 ssizeargfunc sq_item;
278 ssizessizeargfunc sq_slice;
279 ssizeobjargproc sq_ass_item;
280 ssizessizeobjargproc sq_ass_slice;
281 objobjproc sq_contains;
282 /* Added in release 2.0 */
283 binaryfunc sq_inplace_concat;
284 ssizeargfunc sq_inplace_repeat;
285 } PySequenceMethods;
287 typedef struct {
288 lenfunc mp_length;
289 binaryfunc mp_subscript;
290 objobjargproc mp_ass_subscript;
291 } PyMappingMethods;
293 typedef struct {
294 readbufferproc bf_getreadbuffer;
295 writebufferproc bf_getwritebuffer;
296 segcountproc bf_getsegcount;
297 charbufferproc bf_getcharbuffer;
298 getbufferproc bf_getbuffer;
299 releasebufferproc bf_releasebuffer;
300 } PyBufferProcs;
303 typedef void (*freefunc)(void *);
304 typedef void (*destructor)(PyObject *);
305 typedef int (*printfunc)(PyObject *, FILE *, int);
306 typedef PyObject *(*getattrfunc)(PyObject *, char *);
307 typedef PyObject *(*getattrofunc)(PyObject *, PyObject *);
308 typedef int (*setattrfunc)(PyObject *, char *, PyObject *);
309 typedef int (*setattrofunc)(PyObject *, PyObject *, PyObject *);
310 typedef int (*cmpfunc)(PyObject *, PyObject *);
311 typedef PyObject *(*reprfunc)(PyObject *);
312 typedef long (*hashfunc)(PyObject *);
313 typedef PyObject *(*richcmpfunc) (PyObject *, PyObject *, int);
314 typedef PyObject *(*getiterfunc) (PyObject *);
315 typedef PyObject *(*iternextfunc) (PyObject *);
316 typedef PyObject *(*descrgetfunc) (PyObject *, PyObject *, PyObject *);
317 typedef int (*descrsetfunc) (PyObject *, PyObject *, PyObject *);
318 typedef int (*initproc)(PyObject *, PyObject *, PyObject *);
319 typedef PyObject *(*newfunc)(struct _typeobject *, PyObject *, PyObject *);
320 typedef PyObject *(*allocfunc)(struct _typeobject *, Py_ssize_t);
322 typedef struct _typeobject {
323 PyObject_VAR_HEAD
324 const char *tp_name; /* For printing, in format "<module>.<name>" */
325 Py_ssize_t tp_basicsize, tp_itemsize; /* For allocation */
327 /* Methods to implement standard operations */
329 destructor tp_dealloc;
330 printfunc tp_print;
331 getattrfunc tp_getattr;
332 setattrfunc tp_setattr;
333 cmpfunc tp_compare;
334 reprfunc tp_repr;
336 /* Method suites for standard classes */
338 PyNumberMethods *tp_as_number;
339 PySequenceMethods *tp_as_sequence;
340 PyMappingMethods *tp_as_mapping;
342 /* More standard operations (here for binary compatibility) */
344 hashfunc tp_hash;
345 ternaryfunc tp_call;
346 reprfunc tp_str;
347 getattrofunc tp_getattro;
348 setattrofunc tp_setattro;
350 /* Functions to access object as input/output buffer */
351 PyBufferProcs *tp_as_buffer;
353 /* Flags to define presence of optional/expanded features */
354 long tp_flags;
356 const char *tp_doc; /* Documentation string */
358 /* Assigned meaning in release 2.0 */
359 /* call function for all accessible objects */
360 traverseproc tp_traverse;
362 /* delete references to contained objects */
363 inquiry tp_clear;
365 /* Assigned meaning in release 2.1 */
366 /* rich comparisons */
367 richcmpfunc tp_richcompare;
369 /* weak reference enabler */
370 Py_ssize_t tp_weaklistoffset;
372 /* Added in release 2.2 */
373 /* Iterators */
374 getiterfunc tp_iter;
375 iternextfunc tp_iternext;
377 /* Attribute descriptor and subclassing stuff */
378 struct PyMethodDef *tp_methods;
379 struct PyMemberDef *tp_members;
380 struct PyGetSetDef *tp_getset;
381 struct _typeobject *tp_base;
382 PyObject *tp_dict;
383 descrgetfunc tp_descr_get;
384 descrsetfunc tp_descr_set;
385 Py_ssize_t tp_dictoffset;
386 initproc tp_init;
387 allocfunc tp_alloc;
388 newfunc tp_new;
389 freefunc tp_free; /* Low-level free-memory routine */
390 inquiry tp_is_gc; /* For PyObject_IS_GC */
391 PyObject *tp_bases;
392 PyObject *tp_mro; /* method resolution order */
393 PyObject *tp_cache;
394 PyObject *tp_subclasses;
395 PyObject *tp_weaklist;
396 destructor tp_del;
398 /* Type attribute cache version tag. Added in version 2.6 */
399 unsigned int tp_version_tag;
401 #ifdef COUNT_ALLOCS
402 /* these must be last and never explicitly initialized */
403 Py_ssize_t tp_allocs;
404 Py_ssize_t tp_frees;
405 Py_ssize_t tp_maxalloc;
406 struct _typeobject *tp_prev;
407 struct _typeobject *tp_next;
408 #endif
409 } PyTypeObject;
412 /* The *real* layout of a type object when allocated on the heap */
413 typedef struct _heaptypeobject {
414 /* Note: there's a dependency on the order of these members
415 in slotptr() in typeobject.c . */
416 PyTypeObject ht_type;
417 PyNumberMethods as_number;
418 PyMappingMethods as_mapping;
419 PySequenceMethods as_sequence; /* as_sequence comes after as_mapping,
420 so that the mapping wins when both
421 the mapping and the sequence define
422 a given operator (e.g. __getitem__).
423 see add_operators() in typeobject.c . */
424 PyBufferProcs as_buffer;
425 PyObject *ht_name, *ht_slots;
426 /* here are optional user slots, followed by the members. */
427 } PyHeapTypeObject;
429 /* access macro to the members which are floating "behind" the object */
430 #define PyHeapType_GET_MEMBERS(etype) \
431 ((PyMemberDef *)(((char *)etype) + Py_TYPE(etype)->tp_basicsize))
434 /* Generic type check */
435 PyAPI_FUNC(int) PyType_IsSubtype(PyTypeObject *, PyTypeObject *);
436 #define PyObject_TypeCheck(ob, tp) \
437 (Py_TYPE(ob) == (tp) || PyType_IsSubtype(Py_TYPE(ob), (tp)))
439 PyAPI_DATA(PyTypeObject) PyType_Type; /* built-in 'type' */
440 PyAPI_DATA(PyTypeObject) PyBaseObject_Type; /* built-in 'object' */
441 PyAPI_DATA(PyTypeObject) PySuper_Type; /* built-in 'super' */
443 #define PyType_Check(op) \
444 PyType_FastSubclass(Py_TYPE(op), Py_TPFLAGS_TYPE_SUBCLASS)
445 #define PyType_CheckExact(op) (Py_TYPE(op) == &PyType_Type)
447 PyAPI_FUNC(int) PyType_Ready(PyTypeObject *);
448 PyAPI_FUNC(PyObject *) PyType_GenericAlloc(PyTypeObject *, Py_ssize_t);
449 PyAPI_FUNC(PyObject *) PyType_GenericNew(PyTypeObject *,
450 PyObject *, PyObject *);
451 PyAPI_FUNC(PyObject *) _PyType_Lookup(PyTypeObject *, PyObject *);
452 PyAPI_FUNC(unsigned int) PyType_ClearCache(void);
453 PyAPI_FUNC(void) PyType_Modified(PyTypeObject *);
455 /* Generic operations on objects */
456 PyAPI_FUNC(int) PyObject_Print(PyObject *, FILE *, int);
457 PyAPI_FUNC(void) _PyObject_Dump(PyObject *);
458 PyAPI_FUNC(PyObject *) PyObject_Repr(PyObject *);
459 PyAPI_FUNC(PyObject *) _PyObject_Str(PyObject *);
460 PyAPI_FUNC(PyObject *) PyObject_Str(PyObject *);
461 #define PyObject_Bytes PyObject_Str
462 #ifdef Py_USING_UNICODE
463 PyAPI_FUNC(PyObject *) PyObject_Unicode(PyObject *);
464 #endif
465 PyAPI_FUNC(int) PyObject_Compare(PyObject *, PyObject *);
466 PyAPI_FUNC(PyObject *) PyObject_RichCompare(PyObject *, PyObject *, int);
467 PyAPI_FUNC(int) PyObject_RichCompareBool(PyObject *, PyObject *, int);
468 PyAPI_FUNC(PyObject *) PyObject_GetAttrString(PyObject *, const char *);
469 PyAPI_FUNC(int) PyObject_SetAttrString(PyObject *, const char *, PyObject *);
470 PyAPI_FUNC(int) PyObject_HasAttrString(PyObject *, const char *);
471 PyAPI_FUNC(PyObject *) PyObject_GetAttr(PyObject *, PyObject *);
472 PyAPI_FUNC(int) PyObject_SetAttr(PyObject *, PyObject *, PyObject *);
473 PyAPI_FUNC(int) PyObject_HasAttr(PyObject *, PyObject *);
474 PyAPI_FUNC(PyObject **) _PyObject_GetDictPtr(PyObject *);
475 PyAPI_FUNC(PyObject *) PyObject_SelfIter(PyObject *);
476 PyAPI_FUNC(PyObject *) _PyObject_NextNotImplemented(PyObject *);
477 PyAPI_FUNC(PyObject *) PyObject_GenericGetAttr(PyObject *, PyObject *);
478 PyAPI_FUNC(int) PyObject_GenericSetAttr(PyObject *,
479 PyObject *, PyObject *);
480 PyAPI_FUNC(long) PyObject_Hash(PyObject *);
481 PyAPI_FUNC(long) PyObject_HashNotImplemented(PyObject *);
482 PyAPI_FUNC(int) PyObject_IsTrue(PyObject *);
483 PyAPI_FUNC(int) PyObject_Not(PyObject *);
484 PyAPI_FUNC(int) PyCallable_Check(PyObject *);
485 PyAPI_FUNC(int) PyNumber_Coerce(PyObject **, PyObject **);
486 PyAPI_FUNC(int) PyNumber_CoerceEx(PyObject **, PyObject **);
488 PyAPI_FUNC(void) PyObject_ClearWeakRefs(PyObject *);
490 /* A slot function whose address we need to compare */
491 extern int _PyObject_SlotCompare(PyObject *, PyObject *);
494 /* PyObject_Dir(obj) acts like Python __builtin__.dir(obj), returning a
495 list of strings. PyObject_Dir(NULL) is like __builtin__.dir(),
496 returning the names of the current locals. In this case, if there are
497 no current locals, NULL is returned, and PyErr_Occurred() is false.
499 PyAPI_FUNC(PyObject *) PyObject_Dir(PyObject *);
502 /* Helpers for printing recursive container types */
503 PyAPI_FUNC(int) Py_ReprEnter(PyObject *);
504 PyAPI_FUNC(void) Py_ReprLeave(PyObject *);
506 /* Helpers for hash functions */
507 PyAPI_FUNC(long) _Py_HashDouble(double);
508 PyAPI_FUNC(long) _Py_HashPointer(void*);
510 /* Helper for passing objects to printf and the like */
511 #define PyObject_REPR(obj) PyString_AS_STRING(PyObject_Repr(obj))
513 /* Flag bits for printing: */
514 #define Py_PRINT_RAW 1 /* No string quotes etc. */
517 `Type flags (tp_flags)
519 These flags are used to extend the type structure in a backwards-compatible
520 fashion. Extensions can use the flags to indicate (and test) when a given
521 type structure contains a new feature. The Python core will use these when
522 introducing new functionality between major revisions (to avoid mid-version
523 changes in the PYTHON_API_VERSION).
525 Arbitration of the flag bit positions will need to be coordinated among
526 all extension writers who publically release their extensions (this will
527 be fewer than you might expect!)..
529 Python 1.5.2 introduced the bf_getcharbuffer slot into PyBufferProcs.
531 Type definitions should use Py_TPFLAGS_DEFAULT for their tp_flags value.
533 Code can use PyType_HasFeature(type_ob, flag_value) to test whether the
534 given type object has a specified feature.
536 NOTE: when building the core, Py_TPFLAGS_DEFAULT includes
537 Py_TPFLAGS_HAVE_VERSION_TAG; outside the core, it doesn't. This is so
538 that extensions that modify tp_dict of their own types directly don't
539 break, since this was allowed in 2.5. In 3.0 they will have to
540 manually remove this flag though!
543 /* PyBufferProcs contains bf_getcharbuffer */
544 #define Py_TPFLAGS_HAVE_GETCHARBUFFER (1L<<0)
546 /* PySequenceMethods contains sq_contains */
547 #define Py_TPFLAGS_HAVE_SEQUENCE_IN (1L<<1)
549 /* This is here for backwards compatibility. Extensions that use the old GC
550 * API will still compile but the objects will not be tracked by the GC. */
551 #define Py_TPFLAGS_GC 0 /* used to be (1L<<2) */
553 /* PySequenceMethods and PyNumberMethods contain in-place operators */
554 #define Py_TPFLAGS_HAVE_INPLACEOPS (1L<<3)
556 /* PyNumberMethods do their own coercion */
557 #define Py_TPFLAGS_CHECKTYPES (1L<<4)
559 /* tp_richcompare is defined */
560 #define Py_TPFLAGS_HAVE_RICHCOMPARE (1L<<5)
562 /* Objects which are weakly referencable if their tp_weaklistoffset is >0 */
563 #define Py_TPFLAGS_HAVE_WEAKREFS (1L<<6)
565 /* tp_iter is defined */
566 #define Py_TPFLAGS_HAVE_ITER (1L<<7)
568 /* New members introduced by Python 2.2 exist */
569 #define Py_TPFLAGS_HAVE_CLASS (1L<<8)
571 /* Set if the type object is dynamically allocated */
572 #define Py_TPFLAGS_HEAPTYPE (1L<<9)
574 /* Set if the type allows subclassing */
575 #define Py_TPFLAGS_BASETYPE (1L<<10)
577 /* Set if the type is 'ready' -- fully initialized */
578 #define Py_TPFLAGS_READY (1L<<12)
580 /* Set while the type is being 'readied', to prevent recursive ready calls */
581 #define Py_TPFLAGS_READYING (1L<<13)
583 /* Objects support garbage collection (see objimp.h) */
584 #define Py_TPFLAGS_HAVE_GC (1L<<14)
586 /* These two bits are preserved for Stackless Python, next after this is 17 */
587 #ifdef STACKLESS
588 #define Py_TPFLAGS_HAVE_STACKLESS_EXTENSION (3L<<15)
589 #else
590 #define Py_TPFLAGS_HAVE_STACKLESS_EXTENSION 0
591 #endif
593 /* Objects support nb_index in PyNumberMethods */
594 #define Py_TPFLAGS_HAVE_INDEX (1L<<17)
596 /* Objects support type attribute cache */
597 #define Py_TPFLAGS_HAVE_VERSION_TAG (1L<<18)
598 #define Py_TPFLAGS_VALID_VERSION_TAG (1L<<19)
600 /* Type is abstract and cannot be instantiated */
601 #define Py_TPFLAGS_IS_ABSTRACT (1L<<20)
603 /* Has the new buffer protocol */
604 #define Py_TPFLAGS_HAVE_NEWBUFFER (1L<<21)
606 /* These flags are used to determine if a type is a subclass. */
607 #define Py_TPFLAGS_INT_SUBCLASS (1L<<23)
608 #define Py_TPFLAGS_LONG_SUBCLASS (1L<<24)
609 #define Py_TPFLAGS_LIST_SUBCLASS (1L<<25)
610 #define Py_TPFLAGS_TUPLE_SUBCLASS (1L<<26)
611 #define Py_TPFLAGS_STRING_SUBCLASS (1L<<27)
612 #define Py_TPFLAGS_UNICODE_SUBCLASS (1L<<28)
613 #define Py_TPFLAGS_DICT_SUBCLASS (1L<<29)
614 #define Py_TPFLAGS_BASE_EXC_SUBCLASS (1L<<30)
615 #define Py_TPFLAGS_TYPE_SUBCLASS (1L<<31)
617 #define Py_TPFLAGS_DEFAULT_EXTERNAL ( \
618 Py_TPFLAGS_HAVE_GETCHARBUFFER | \
619 Py_TPFLAGS_HAVE_SEQUENCE_IN | \
620 Py_TPFLAGS_HAVE_INPLACEOPS | \
621 Py_TPFLAGS_HAVE_RICHCOMPARE | \
622 Py_TPFLAGS_HAVE_WEAKREFS | \
623 Py_TPFLAGS_HAVE_ITER | \
624 Py_TPFLAGS_HAVE_CLASS | \
625 Py_TPFLAGS_HAVE_STACKLESS_EXTENSION | \
626 Py_TPFLAGS_HAVE_INDEX | \
628 #define Py_TPFLAGS_DEFAULT_CORE (Py_TPFLAGS_DEFAULT_EXTERNAL | \
629 Py_TPFLAGS_HAVE_VERSION_TAG)
631 #ifdef Py_BUILD_CORE
632 #define Py_TPFLAGS_DEFAULT Py_TPFLAGS_DEFAULT_CORE
633 #else
634 #define Py_TPFLAGS_DEFAULT Py_TPFLAGS_DEFAULT_EXTERNAL
635 #endif
637 #define PyType_HasFeature(t,f) (((t)->tp_flags & (f)) != 0)
638 #define PyType_FastSubclass(t,f) PyType_HasFeature(t,f)
642 The macros Py_INCREF(op) and Py_DECREF(op) are used to increment or decrement
643 reference counts. Py_DECREF calls the object's deallocator function when
644 the refcount falls to 0; for
645 objects that don't contain references to other objects or heap memory
646 this can be the standard function free(). Both macros can be used
647 wherever a void expression is allowed. The argument must not be a
648 NULL pointer. If it may be NULL, use Py_XINCREF/Py_XDECREF instead.
649 The macro _Py_NewReference(op) initialize reference counts to 1, and
650 in special builds (Py_REF_DEBUG, Py_TRACE_REFS) performs additional
651 bookkeeping appropriate to the special build.
653 We assume that the reference count field can never overflow; this can
654 be proven when the size of the field is the same as the pointer size, so
655 we ignore the possibility. Provided a C int is at least 32 bits (which
656 is implicitly assumed in many parts of this code), that's enough for
657 about 2**31 references to an object.
659 XXX The following became out of date in Python 2.2, but I'm not sure
660 XXX what the full truth is now. Certainly, heap-allocated type objects
661 XXX can and should be deallocated.
662 Type objects should never be deallocated; the type pointer in an object
663 is not considered to be a reference to the type object, to save
664 complications in the deallocation function. (This is actually a
665 decision that's up to the implementer of each new type so if you want,
666 you can count such references to the type object.)
668 *** WARNING*** The Py_DECREF macro must have a side-effect-free argument
669 since it may evaluate its argument multiple times. (The alternative
670 would be to mace it a proper function or assign it to a global temporary
671 variable first, both of which are slower; and in a multi-threaded
672 environment the global variable trick is not safe.)
675 /* First define a pile of simple helper macros, one set per special
676 * build symbol. These either expand to the obvious things, or to
677 * nothing at all when the special mode isn't in effect. The main
678 * macros can later be defined just once then, yet expand to different
679 * things depending on which special build options are and aren't in effect.
680 * Trust me <wink>: while painful, this is 20x easier to understand than,
681 * e.g, defining _Py_NewReference five different times in a maze of nested
682 * #ifdefs (we used to do that -- it was impenetrable).
684 #ifdef Py_REF_DEBUG
685 PyAPI_DATA(Py_ssize_t) _Py_RefTotal;
686 PyAPI_FUNC(void) _Py_NegativeRefcount(const char *fname,
687 int lineno, PyObject *op);
688 PyAPI_FUNC(PyObject *) _PyDict_Dummy(void);
689 PyAPI_FUNC(PyObject *) _PySet_Dummy(void);
690 PyAPI_FUNC(Py_ssize_t) _Py_GetRefTotal(void);
691 #define _Py_INC_REFTOTAL _Py_RefTotal++
692 #define _Py_DEC_REFTOTAL _Py_RefTotal--
693 #define _Py_REF_DEBUG_COMMA ,
694 #define _Py_CHECK_REFCNT(OP) \
695 { if (((PyObject*)OP)->ob_refcnt < 0) \
696 _Py_NegativeRefcount(__FILE__, __LINE__, \
697 (PyObject *)(OP)); \
699 #else
700 #define _Py_INC_REFTOTAL
701 #define _Py_DEC_REFTOTAL
702 #define _Py_REF_DEBUG_COMMA
703 #define _Py_CHECK_REFCNT(OP) /* a semicolon */;
704 #endif /* Py_REF_DEBUG */
706 #ifdef COUNT_ALLOCS
707 PyAPI_FUNC(void) inc_count(PyTypeObject *);
708 PyAPI_FUNC(void) dec_count(PyTypeObject *);
709 #define _Py_INC_TPALLOCS(OP) inc_count(Py_TYPE(OP))
710 #define _Py_INC_TPFREES(OP) dec_count(Py_TYPE(OP))
711 #define _Py_DEC_TPFREES(OP) Py_TYPE(OP)->tp_frees--
712 #define _Py_COUNT_ALLOCS_COMMA ,
713 #else
714 #define _Py_INC_TPALLOCS(OP)
715 #define _Py_INC_TPFREES(OP)
716 #define _Py_DEC_TPFREES(OP)
717 #define _Py_COUNT_ALLOCS_COMMA
718 #endif /* COUNT_ALLOCS */
720 #ifdef Py_TRACE_REFS
721 /* Py_TRACE_REFS is such major surgery that we call external routines. */
722 PyAPI_FUNC(void) _Py_NewReference(PyObject *);
723 PyAPI_FUNC(void) _Py_ForgetReference(PyObject *);
724 PyAPI_FUNC(void) _Py_Dealloc(PyObject *);
725 PyAPI_FUNC(void) _Py_PrintReferences(FILE *);
726 PyAPI_FUNC(void) _Py_PrintReferenceAddresses(FILE *);
727 PyAPI_FUNC(void) _Py_AddToAllObjects(PyObject *, int force);
729 #else
730 /* Without Py_TRACE_REFS, there's little enough to do that we expand code
731 * inline.
733 #define _Py_NewReference(op) ( \
734 _Py_INC_TPALLOCS(op) _Py_COUNT_ALLOCS_COMMA \
735 _Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA \
736 Py_REFCNT(op) = 1)
738 #define _Py_ForgetReference(op) _Py_INC_TPFREES(op)
740 #define _Py_Dealloc(op) ( \
741 _Py_INC_TPFREES(op) _Py_COUNT_ALLOCS_COMMA \
742 (*Py_TYPE(op)->tp_dealloc)((PyObject *)(op)))
743 #endif /* !Py_TRACE_REFS */
745 #define Py_INCREF(op) ( \
746 _Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA \
747 ((PyObject*)(op))->ob_refcnt++)
749 #define Py_DECREF(op) \
750 if (_Py_DEC_REFTOTAL _Py_REF_DEBUG_COMMA \
751 --((PyObject*)(op))->ob_refcnt != 0) \
752 _Py_CHECK_REFCNT(op) \
753 else \
754 _Py_Dealloc((PyObject *)(op))
756 /* Safely decref `op` and set `op` to NULL, especially useful in tp_clear
757 * and tp_dealloc implementatons.
759 * Note that "the obvious" code can be deadly:
761 * Py_XDECREF(op);
762 * op = NULL;
764 * Typically, `op` is something like self->containee, and `self` is done
765 * using its `containee` member. In the code sequence above, suppose
766 * `containee` is non-NULL with a refcount of 1. Its refcount falls to
767 * 0 on the first line, which can trigger an arbitrary amount of code,
768 * possibly including finalizers (like __del__ methods or weakref callbacks)
769 * coded in Python, which in turn can release the GIL and allow other threads
770 * to run, etc. Such code may even invoke methods of `self` again, or cause
771 * cyclic gc to trigger, but-- oops! --self->containee still points to the
772 * object being torn down, and it may be in an insane state while being torn
773 * down. This has in fact been a rich historic source of miserable (rare &
774 * hard-to-diagnose) segfaulting (and other) bugs.
776 * The safe way is:
778 * Py_CLEAR(op);
780 * That arranges to set `op` to NULL _before_ decref'ing, so that any code
781 * triggered as a side-effect of `op` getting torn down no longer believes
782 * `op` points to a valid object.
784 * There are cases where it's safe to use the naive code, but they're brittle.
785 * For example, if `op` points to a Python integer, you know that destroying
786 * one of those can't cause problems -- but in part that relies on that
787 * Python integers aren't currently weakly referencable. Best practice is
788 * to use Py_CLEAR() even if you can't think of a reason for why you need to.
790 #define Py_CLEAR(op) \
791 do { \
792 if (op) { \
793 PyObject *_py_tmp = (PyObject *)(op); \
794 (op) = NULL; \
795 Py_DECREF(_py_tmp); \
797 } while (0)
799 /* Macros to use in case the object pointer may be NULL: */
800 #define Py_XINCREF(op) if ((op) == NULL) ; else Py_INCREF(op)
801 #define Py_XDECREF(op) if ((op) == NULL) ; else Py_DECREF(op)
804 These are provided as conveniences to Python runtime embedders, so that
805 they can have object code that is not dependent on Python compilation flags.
807 PyAPI_FUNC(void) Py_IncRef(PyObject *);
808 PyAPI_FUNC(void) Py_DecRef(PyObject *);
811 _Py_NoneStruct is an object of undefined type which can be used in contexts
812 where NULL (nil) is not suitable (since NULL often means 'error').
814 Don't forget to apply Py_INCREF() when returning this value!!!
816 PyAPI_DATA(PyObject) _Py_NoneStruct; /* Don't use this directly */
817 #define Py_None (&_Py_NoneStruct)
819 /* Macro for returning Py_None from a function */
820 #define Py_RETURN_NONE return Py_INCREF(Py_None), Py_None
823 Py_NotImplemented is a singleton used to signal that an operation is
824 not implemented for a given type combination.
826 PyAPI_DATA(PyObject) _Py_NotImplementedStruct; /* Don't use this directly */
827 #define Py_NotImplemented (&_Py_NotImplementedStruct)
829 /* Rich comparison opcodes */
830 #define Py_LT 0
831 #define Py_LE 1
832 #define Py_EQ 2
833 #define Py_NE 3
834 #define Py_GT 4
835 #define Py_GE 5
837 /* Maps Py_LT to Py_GT, ..., Py_GE to Py_LE.
838 * Defined in object.c.
840 PyAPI_DATA(int) _Py_SwappedOp[];
843 Define staticforward and statichere for source compatibility with old
844 C extensions.
846 The staticforward define was needed to support certain broken C
847 compilers (notably SCO ODT 3.0, perhaps early AIX as well) botched the
848 static keyword when it was used with a forward declaration of a static
849 initialized structure. Standard C allows the forward declaration with
850 static, and we've decided to stop catering to broken C compilers.
851 (In fact, we expect that the compilers are all fixed eight years later.)
854 #define staticforward static
855 #define statichere static
859 More conventions
860 ================
862 Argument Checking
863 -----------------
865 Functions that take objects as arguments normally don't check for nil
866 arguments, but they do check the type of the argument, and return an
867 error if the function doesn't apply to the type.
869 Failure Modes
870 -------------
872 Functions may fail for a variety of reasons, including running out of
873 memory. This is communicated to the caller in two ways: an error string
874 is set (see errors.h), and the function result differs: functions that
875 normally return a pointer return NULL for failure, functions returning
876 an integer return -1 (which could be a legal return value too!), and
877 other functions return 0 for success and -1 for failure.
878 Callers should always check for errors before using the result. If
879 an error was set, the caller must either explicitly clear it, or pass
880 the error on to its caller.
882 Reference Counts
883 ----------------
885 It takes a while to get used to the proper usage of reference counts.
887 Functions that create an object set the reference count to 1; such new
888 objects must be stored somewhere or destroyed again with Py_DECREF().
889 Some functions that 'store' objects, such as PyTuple_SetItem() and
890 PyList_SetItem(),
891 don't increment the reference count of the object, since the most
892 frequent use is to store a fresh object. Functions that 'retrieve'
893 objects, such as PyTuple_GetItem() and PyDict_GetItemString(), also
894 don't increment
895 the reference count, since most frequently the object is only looked at
896 quickly. Thus, to retrieve an object and store it again, the caller
897 must call Py_INCREF() explicitly.
899 NOTE: functions that 'consume' a reference count, like
900 PyList_SetItem(), consume the reference even if the object wasn't
901 successfully stored, to simplify error handling.
903 It seems attractive to make other functions that take an object as
904 argument consume a reference count; however, this may quickly get
905 confusing (even the current practice is already confusing). Consider
906 it carefully, it may save lots of calls to Py_INCREF() and Py_DECREF() at
907 times.
911 /* Trashcan mechanism, thanks to Christian Tismer.
913 When deallocating a container object, it's possible to trigger an unbounded
914 chain of deallocations, as each Py_DECREF in turn drops the refcount on "the
915 next" object in the chain to 0. This can easily lead to stack faults, and
916 especially in threads (which typically have less stack space to work with).
918 A container object that participates in cyclic gc can avoid this by
919 bracketing the body of its tp_dealloc function with a pair of macros:
921 static void
922 mytype_dealloc(mytype *p)
924 ... declarations go here ...
926 PyObject_GC_UnTrack(p); // must untrack first
927 Py_TRASHCAN_SAFE_BEGIN(p)
928 ... The body of the deallocator goes here, including all calls ...
929 ... to Py_DECREF on contained objects. ...
930 Py_TRASHCAN_SAFE_END(p)
933 CAUTION: Never return from the middle of the body! If the body needs to
934 "get out early", put a label immediately before the Py_TRASHCAN_SAFE_END
935 call, and goto it. Else the call-depth counter (see below) will stay
936 above 0 forever, and the trashcan will never get emptied.
938 How it works: The BEGIN macro increments a call-depth counter. So long
939 as this counter is small, the body of the deallocator is run directly without
940 further ado. But if the counter gets large, it instead adds p to a list of
941 objects to be deallocated later, skips the body of the deallocator, and
942 resumes execution after the END macro. The tp_dealloc routine then returns
943 without deallocating anything (and so unbounded call-stack depth is avoided).
945 When the call stack finishes unwinding again, code generated by the END macro
946 notices this, and calls another routine to deallocate all the objects that
947 may have been added to the list of deferred deallocations. In effect, a
948 chain of N deallocations is broken into N / PyTrash_UNWIND_LEVEL pieces,
949 with the call stack never exceeding a depth of PyTrash_UNWIND_LEVEL.
952 PyAPI_FUNC(void) _PyTrash_deposit_object(PyObject*);
953 PyAPI_FUNC(void) _PyTrash_destroy_chain(void);
954 PyAPI_DATA(int) _PyTrash_delete_nesting;
955 PyAPI_DATA(PyObject *) _PyTrash_delete_later;
957 #define PyTrash_UNWIND_LEVEL 50
959 #define Py_TRASHCAN_SAFE_BEGIN(op) \
960 if (_PyTrash_delete_nesting < PyTrash_UNWIND_LEVEL) { \
961 ++_PyTrash_delete_nesting;
962 /* The body of the deallocator is here. */
963 #define Py_TRASHCAN_SAFE_END(op) \
964 --_PyTrash_delete_nesting; \
965 if (_PyTrash_delete_later && _PyTrash_delete_nesting <= 0) \
966 _PyTrash_destroy_chain(); \
968 else \
969 _PyTrash_deposit_object((PyObject*)op);
971 #ifdef __cplusplus
973 #endif
974 #endif /* !Py_OBJECT_H */