Guido van Rossum | a330996 | 1993-07-28 09:05:47 +0000 | [diff] [blame] | 1 | #ifndef Py_OBJECT_H |
| 2 | #define Py_OBJECT_H |
| 3 | #ifdef __cplusplus |
| 4 | extern "C" { |
| 5 | #endif |
| 6 | |
Guido van Rossum | f70e43a | 1991-02-19 12:39:46 +0000 | [diff] [blame] | 7 | |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 8 | /* Object and type object interface */ |
| 9 | |
| 10 | /* |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 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 |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 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). |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 18 | |
| 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. |
| 23 | |
| 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!). |
| 30 | |
| 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.) |
| 39 | |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 40 | Objects are always accessed through pointers of the type 'PyObject *'. |
| 41 | The type 'PyObject' is a structure that only contains the reference count |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 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 |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 45 | with the reference count and type fields; the macro PyObject_HEAD should be |
Thomas Wouters | 7e47402 | 2000-07-16 12:04:32 +0000 | [diff] [blame] | 46 | used for this (to accommodate for future changes). The implementation |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 47 | of a particular object type can cast the object pointer to the proper |
| 48 | type and back. |
| 49 | |
| 50 | A standard interface exists for objects that contain an array of items |
| 51 | whose size is determined when the object is allocated. |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 52 | */ |
| 53 | |
Tim Peters | 3459251 | 2002-07-11 06:23:50 +0000 | [diff] [blame] | 54 | /* Py_DEBUG implies Py_TRACE_REFS. */ |
| 55 | #if defined(Py_DEBUG) && !defined(Py_TRACE_REFS) |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 56 | #define Py_TRACE_REFS |
Tim Peters | 3459251 | 2002-07-11 06:23:50 +0000 | [diff] [blame] | 57 | #endif |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 58 | |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 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 |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 63 | |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 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; |
| 69 | |
| 70 | #define _PyObject_EXTRA_INIT 0, 0, |
| 71 | |
| 72 | #else |
| 73 | #define _PyObject_HEAD_EXTRA |
| 74 | #define _PyObject_EXTRA_INIT |
| 75 | #endif |
| 76 | |
| 77 | /* PyObject_HEAD defines the initial segment of every PyObject. */ |
| 78 | #define PyObject_HEAD \ |
| 79 | _PyObject_HEAD_EXTRA \ |
Martin v. Löwis | e36dce6 | 2006-03-01 04:02:43 +0000 | [diff] [blame] | 80 | Py_ssize_t ob_refcnt; \ |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 81 | struct _typeobject *ob_type; |
| 82 | |
| 83 | #define PyObject_HEAD_INIT(type) \ |
| 84 | _PyObject_EXTRA_INIT \ |
| 85 | 1, type, |
| 86 | |
| 87 | /* PyObject_VAR_HEAD defines the initial segment of all variable-size |
| 88 | * container objects. These end with a declaration of an array with 1 |
| 89 | * element, but enough space is malloc'ed so that the array actually |
| 90 | * has room for ob_size elements. Note that ob_size is an element count, |
| 91 | * not necessarily a byte count. |
| 92 | */ |
| 93 | #define PyObject_VAR_HEAD \ |
| 94 | PyObject_HEAD \ |
Martin v. Löwis | 18e1655 | 2006-02-15 17:27:45 +0000 | [diff] [blame] | 95 | Py_ssize_t ob_size; /* Number of items in variable part */ |
| 96 | #define Py_INVALID_SIZE (Py_ssize_t)-1 |
Tim Peters | 803526b | 2002-07-07 05:13:56 +0000 | [diff] [blame] | 97 | |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 98 | /* Nothing is actually declared to be a PyObject, but every pointer to |
| 99 | * a Python object can be cast to a PyObject*. This is inheritance built |
| 100 | * by hand. Similarly every pointer to a variable-size Python object can, |
| 101 | * in addition, be cast to PyVarObject*. |
| 102 | */ |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 103 | typedef struct _object { |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 104 | PyObject_HEAD |
| 105 | } PyObject; |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 106 | |
| 107 | typedef struct { |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 108 | PyObject_VAR_HEAD |
Guido van Rossum | d0c87ee | 1997-05-15 21:31:03 +0000 | [diff] [blame] | 109 | } PyVarObject; |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 110 | |
| 111 | |
| 112 | /* |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 113 | Type objects contain a string containing the type name (to help somewhat |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 114 | in debugging), the allocation parameters (see PyObject_New() and |
| 115 | PyObject_NewVar()), |
| 116 | and methods for accessing objects of the type. Methods are optional, a |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 117 | nil pointer meaning that particular kind of access is not available for |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 118 | this type. The Py_DECREF() macro uses the tp_dealloc method without |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 119 | checking for a nil pointer; it should always be implemented except if |
| 120 | the implementation can guarantee that the reference count will never |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 121 | reach zero (e.g., for statically allocated type objects). |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 122 | |
| 123 | NB: the methods for certain type groups are now contained in separate |
| 124 | method blocks. |
| 125 | */ |
| 126 | |
Tim Peters | 9ace6bc | 2000-07-08 00:32:04 +0000 | [diff] [blame] | 127 | typedef PyObject * (*unaryfunc)(PyObject *); |
| 128 | typedef PyObject * (*binaryfunc)(PyObject *, PyObject *); |
| 129 | typedef PyObject * (*ternaryfunc)(PyObject *, PyObject *, PyObject *); |
| 130 | typedef int (*inquiry)(PyObject *); |
Martin v. Löwis | 18e1655 | 2006-02-15 17:27:45 +0000 | [diff] [blame] | 131 | typedef Py_ssize_t (*lenfunc)(PyObject *); |
Tim Peters | 9ace6bc | 2000-07-08 00:32:04 +0000 | [diff] [blame] | 132 | typedef int (*coercion)(PyObject **, PyObject **); |
Martin v. Löwis | 18e1655 | 2006-02-15 17:27:45 +0000 | [diff] [blame] | 133 | typedef PyObject *(*ssizeargfunc)(PyObject *, Py_ssize_t); |
| 134 | typedef PyObject *(*ssizessizeargfunc)(PyObject *, Py_ssize_t, Py_ssize_t); |
Martin v. Löwis | 18e1655 | 2006-02-15 17:27:45 +0000 | [diff] [blame] | 135 | typedef int(*ssizeobjargproc)(PyObject *, Py_ssize_t, PyObject *); |
| 136 | typedef int(*ssizessizeobjargproc)(PyObject *, Py_ssize_t, Py_ssize_t, PyObject *); |
Tim Peters | 9ace6bc | 2000-07-08 00:32:04 +0000 | [diff] [blame] | 137 | typedef int(*objobjargproc)(PyObject *, PyObject *, PyObject *); |
Martin v. Löwis | 18e1655 | 2006-02-15 17:27:45 +0000 | [diff] [blame] | 138 | |
Martin v. Löwis | 18e1655 | 2006-02-15 17:27:45 +0000 | [diff] [blame] | 139 | /* ssize_t-based buffer interface */ |
| 140 | typedef Py_ssize_t (*readbufferproc)(PyObject *, Py_ssize_t, void **); |
| 141 | typedef Py_ssize_t (*writebufferproc)(PyObject *, Py_ssize_t, void **); |
| 142 | typedef Py_ssize_t (*segcountproc)(PyObject *, Py_ssize_t *); |
Martin v. Löwis | 15e6274 | 2006-02-27 16:46:16 +0000 | [diff] [blame] | 143 | typedef Py_ssize_t (*charbufferproc)(PyObject *, Py_ssize_t, char **); |
Martin v. Löwis | 18e1655 | 2006-02-15 17:27:45 +0000 | [diff] [blame] | 144 | |
Tim Peters | 9ace6bc | 2000-07-08 00:32:04 +0000 | [diff] [blame] | 145 | typedef int (*objobjproc)(PyObject *, PyObject *); |
| 146 | typedef int (*visitproc)(PyObject *, void *); |
| 147 | typedef int (*traverseproc)(PyObject *, visitproc, void *); |
Guido van Rossum | b6775db | 1994-08-01 11:34:53 +0000 | [diff] [blame] | 148 | |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 149 | typedef struct { |
Guido van Rossum | 50e9fb9 | 2006-08-17 05:42:55 +0000 | [diff] [blame] | 150 | /* Number implementations must check *both* |
Guido van Rossum | 5f284ce | 2001-01-17 15:20:39 +0000 | [diff] [blame] | 151 | arguments for proper type and implement the necessary conversions |
| 152 | in the slot functions themselves. */ |
Neil Schemenauer | a7ed694 | 2001-01-04 01:31:50 +0000 | [diff] [blame] | 153 | |
Guido van Rossum | b6775db | 1994-08-01 11:34:53 +0000 | [diff] [blame] | 154 | binaryfunc nb_add; |
| 155 | binaryfunc nb_subtract; |
| 156 | binaryfunc nb_multiply; |
Guido van Rossum | b6775db | 1994-08-01 11:34:53 +0000 | [diff] [blame] | 157 | binaryfunc nb_remainder; |
| 158 | binaryfunc nb_divmod; |
Guido van Rossum | 75abc63 | 1994-08-09 13:21:54 +0000 | [diff] [blame] | 159 | ternaryfunc nb_power; |
Guido van Rossum | b6775db | 1994-08-01 11:34:53 +0000 | [diff] [blame] | 160 | unaryfunc nb_negative; |
| 161 | unaryfunc nb_positive; |
| 162 | unaryfunc nb_absolute; |
Jack Diederich | 4dafcc4 | 2006-11-28 19:15:13 +0000 | [diff] [blame] | 163 | inquiry nb_bool; |
Guido van Rossum | b6775db | 1994-08-01 11:34:53 +0000 | [diff] [blame] | 164 | unaryfunc nb_invert; |
| 165 | binaryfunc nb_lshift; |
| 166 | binaryfunc nb_rshift; |
| 167 | binaryfunc nb_and; |
| 168 | binaryfunc nb_xor; |
| 169 | binaryfunc nb_or; |
| 170 | coercion nb_coerce; |
| 171 | unaryfunc nb_int; |
| 172 | unaryfunc nb_long; |
| 173 | unaryfunc nb_float; |
| 174 | unaryfunc nb_oct; |
| 175 | unaryfunc nb_hex; |
Guido van Rossum | 50e9fb9 | 2006-08-17 05:42:55 +0000 | [diff] [blame] | 176 | |
Thomas Wouters | dd8dbdb | 2000-08-24 20:09:45 +0000 | [diff] [blame] | 177 | binaryfunc nb_inplace_add; |
| 178 | binaryfunc nb_inplace_subtract; |
| 179 | binaryfunc nb_inplace_multiply; |
Thomas Wouters | dd8dbdb | 2000-08-24 20:09:45 +0000 | [diff] [blame] | 180 | binaryfunc nb_inplace_remainder; |
| 181 | ternaryfunc nb_inplace_power; |
| 182 | binaryfunc nb_inplace_lshift; |
| 183 | binaryfunc nb_inplace_rshift; |
| 184 | binaryfunc nb_inplace_and; |
| 185 | binaryfunc nb_inplace_xor; |
| 186 | binaryfunc nb_inplace_or; |
Guido van Rossum | 4668b00 | 2001-08-08 05:00:18 +0000 | [diff] [blame] | 187 | |
Guido van Rossum | 4668b00 | 2001-08-08 05:00:18 +0000 | [diff] [blame] | 188 | binaryfunc nb_floor_divide; |
| 189 | binaryfunc nb_true_divide; |
| 190 | binaryfunc nb_inplace_floor_divide; |
| 191 | binaryfunc nb_inplace_true_divide; |
Guido van Rossum | 38fff8c | 2006-03-07 18:50:55 +0000 | [diff] [blame] | 192 | |
Thomas Wouters | 00ee7ba | 2006-08-21 19:07:27 +0000 | [diff] [blame] | 193 | unaryfunc nb_index; |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 194 | } PyNumberMethods; |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 195 | |
| 196 | typedef struct { |
Martin v. Löwis | 18e1655 | 2006-02-15 17:27:45 +0000 | [diff] [blame] | 197 | lenfunc sq_length; |
Guido van Rossum | b6775db | 1994-08-01 11:34:53 +0000 | [diff] [blame] | 198 | binaryfunc sq_concat; |
Martin v. Löwis | 18e1655 | 2006-02-15 17:27:45 +0000 | [diff] [blame] | 199 | ssizeargfunc sq_repeat; |
| 200 | ssizeargfunc sq_item; |
| 201 | ssizessizeargfunc sq_slice; |
| 202 | ssizeobjargproc sq_ass_item; |
| 203 | ssizessizeobjargproc sq_ass_slice; |
Guido van Rossum | cecb27a | 2000-02-28 15:00:40 +0000 | [diff] [blame] | 204 | objobjproc sq_contains; |
Guido van Rossum | 50e9fb9 | 2006-08-17 05:42:55 +0000 | [diff] [blame] | 205 | |
Thomas Wouters | dd8dbdb | 2000-08-24 20:09:45 +0000 | [diff] [blame] | 206 | binaryfunc sq_inplace_concat; |
Martin v. Löwis | 18e1655 | 2006-02-15 17:27:45 +0000 | [diff] [blame] | 207 | ssizeargfunc sq_inplace_repeat; |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 208 | } PySequenceMethods; |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 209 | |
| 210 | typedef struct { |
Martin v. Löwis | 18e1655 | 2006-02-15 17:27:45 +0000 | [diff] [blame] | 211 | lenfunc mp_length; |
Guido van Rossum | b6775db | 1994-08-01 11:34:53 +0000 | [diff] [blame] | 212 | binaryfunc mp_subscript; |
| 213 | objobjargproc mp_ass_subscript; |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 214 | } PyMappingMethods; |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 215 | |
Guido van Rossum | fdf95dd | 1997-05-05 22:15:02 +0000 | [diff] [blame] | 216 | typedef struct { |
Martin v. Löwis | 18e1655 | 2006-02-15 17:27:45 +0000 | [diff] [blame] | 217 | readbufferproc bf_getreadbuffer; |
| 218 | writebufferproc bf_getwritebuffer; |
| 219 | segcountproc bf_getsegcount; |
| 220 | charbufferproc bf_getcharbuffer; |
Guido van Rossum | fdf95dd | 1997-05-05 22:15:02 +0000 | [diff] [blame] | 221 | } PyBufferProcs; |
Tim Peters | 803526b | 2002-07-07 05:13:56 +0000 | [diff] [blame] | 222 | |
Guido van Rossum | fdf95dd | 1997-05-05 22:15:02 +0000 | [diff] [blame] | 223 | |
Neil Schemenauer | f6d1ea1 | 2002-04-12 01:57:06 +0000 | [diff] [blame] | 224 | typedef void (*freefunc)(void *); |
Tim Peters | 9ace6bc | 2000-07-08 00:32:04 +0000 | [diff] [blame] | 225 | typedef void (*destructor)(PyObject *); |
| 226 | typedef int (*printfunc)(PyObject *, FILE *, int); |
Martin v. Löwis | 15e6274 | 2006-02-27 16:46:16 +0000 | [diff] [blame] | 227 | typedef PyObject *(*getattrfunc)(PyObject *, char *); |
Tim Peters | 9ace6bc | 2000-07-08 00:32:04 +0000 | [diff] [blame] | 228 | typedef PyObject *(*getattrofunc)(PyObject *, PyObject *); |
Martin v. Löwis | 15e6274 | 2006-02-27 16:46:16 +0000 | [diff] [blame] | 229 | typedef int (*setattrfunc)(PyObject *, char *, PyObject *); |
Tim Peters | 9ace6bc | 2000-07-08 00:32:04 +0000 | [diff] [blame] | 230 | typedef int (*setattrofunc)(PyObject *, PyObject *, PyObject *); |
| 231 | typedef int (*cmpfunc)(PyObject *, PyObject *); |
| 232 | typedef PyObject *(*reprfunc)(PyObject *); |
| 233 | typedef long (*hashfunc)(PyObject *); |
Guido van Rossum | 5f284ce | 2001-01-17 15:20:39 +0000 | [diff] [blame] | 234 | typedef PyObject *(*richcmpfunc) (PyObject *, PyObject *, int); |
Guido van Rossum | 59d1d2b | 2001-04-20 19:13:02 +0000 | [diff] [blame] | 235 | typedef PyObject *(*getiterfunc) (PyObject *); |
Guido van Rossum | 213c7a6 | 2001-04-23 14:08:49 +0000 | [diff] [blame] | 236 | typedef PyObject *(*iternextfunc) (PyObject *); |
Tim Peters | 6d6c1a3 | 2001-08-02 04:15:00 +0000 | [diff] [blame] | 237 | typedef PyObject *(*descrgetfunc) (PyObject *, PyObject *, PyObject *); |
| 238 | typedef int (*descrsetfunc) (PyObject *, PyObject *, PyObject *); |
| 239 | typedef int (*initproc)(PyObject *, PyObject *, PyObject *); |
| 240 | typedef PyObject *(*newfunc)(struct _typeobject *, PyObject *, PyObject *); |
Martin v. Löwis | 18e1655 | 2006-02-15 17:27:45 +0000 | [diff] [blame] | 241 | typedef PyObject *(*allocfunc)(struct _typeobject *, Py_ssize_t); |
Guido van Rossum | b6775db | 1994-08-01 11:34:53 +0000 | [diff] [blame] | 242 | |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 243 | typedef struct _typeobject { |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 244 | PyObject_VAR_HEAD |
Jeremy Hylton | af68c87 | 2005-12-10 18:50:16 +0000 | [diff] [blame] | 245 | const char *tp_name; /* For printing, in format "<module>.<name>" */ |
Martin v. Löwis | 97c65a8 | 2006-02-16 14:24:38 +0000 | [diff] [blame] | 246 | Py_ssize_t tp_basicsize, tp_itemsize; /* For allocation */ |
Tim Peters | 803526b | 2002-07-07 05:13:56 +0000 | [diff] [blame] | 247 | |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 248 | /* Methods to implement standard operations */ |
Tim Peters | 803526b | 2002-07-07 05:13:56 +0000 | [diff] [blame] | 249 | |
Guido van Rossum | b6775db | 1994-08-01 11:34:53 +0000 | [diff] [blame] | 250 | destructor tp_dealloc; |
| 251 | printfunc tp_print; |
| 252 | getattrfunc tp_getattr; |
| 253 | setattrfunc tp_setattr; |
| 254 | cmpfunc tp_compare; |
| 255 | reprfunc tp_repr; |
Tim Peters | 803526b | 2002-07-07 05:13:56 +0000 | [diff] [blame] | 256 | |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 257 | /* Method suites for standard classes */ |
Tim Peters | 803526b | 2002-07-07 05:13:56 +0000 | [diff] [blame] | 258 | |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 259 | PyNumberMethods *tp_as_number; |
| 260 | PySequenceMethods *tp_as_sequence; |
| 261 | PyMappingMethods *tp_as_mapping; |
Guido van Rossum | 9bfef44 | 1993-03-29 10:43:31 +0000 | [diff] [blame] | 262 | |
Fred Drake | 0e12bcd | 2000-03-21 16:14:47 +0000 | [diff] [blame] | 263 | /* More standard operations (here for binary compatibility) */ |
Guido van Rossum | 9bfef44 | 1993-03-29 10:43:31 +0000 | [diff] [blame] | 264 | |
Guido van Rossum | b6775db | 1994-08-01 11:34:53 +0000 | [diff] [blame] | 265 | hashfunc tp_hash; |
Guido van Rossum | 884afd6 | 1995-07-18 14:21:06 +0000 | [diff] [blame] | 266 | ternaryfunc tp_call; |
Guido van Rossum | 6fde390 | 1995-01-07 10:32:04 +0000 | [diff] [blame] | 267 | reprfunc tp_str; |
Guido van Rossum | 0693dd2 | 1996-08-09 20:48:52 +0000 | [diff] [blame] | 268 | getattrofunc tp_getattro; |
| 269 | setattrofunc tp_setattro; |
Guido van Rossum | 6fde390 | 1995-01-07 10:32:04 +0000 | [diff] [blame] | 270 | |
Guido van Rossum | fdf95dd | 1997-05-05 22:15:02 +0000 | [diff] [blame] | 271 | /* Functions to access object as input/output buffer */ |
| 272 | PyBufferProcs *tp_as_buffer; |
Tim Peters | 803526b | 2002-07-07 05:13:56 +0000 | [diff] [blame] | 273 | |
Guido van Rossum | 36eef3c | 1998-10-08 02:10:56 +0000 | [diff] [blame] | 274 | /* Flags to define presence of optional/expanded features */ |
| 275 | long tp_flags; |
Guido van Rossum | 6fde390 | 1995-01-07 10:32:04 +0000 | [diff] [blame] | 276 | |
Jeremy Hylton | af68c87 | 2005-12-10 18:50:16 +0000 | [diff] [blame] | 277 | const char *tp_doc; /* Documentation string */ |
Guido van Rossum | 6fde390 | 1995-01-07 10:32:04 +0000 | [diff] [blame] | 278 | |
Fred Drake | d55657b | 2001-08-15 18:32:33 +0000 | [diff] [blame] | 279 | /* Assigned meaning in release 2.0 */ |
Jeremy Hylton | 8caad49 | 2000-06-23 14:18:11 +0000 | [diff] [blame] | 280 | /* call function for all accessible objects */ |
| 281 | traverseproc tp_traverse; |
Tim Peters | 803526b | 2002-07-07 05:13:56 +0000 | [diff] [blame] | 282 | |
Jeremy Hylton | 8caad49 | 2000-06-23 14:18:11 +0000 | [diff] [blame] | 283 | /* delete references to contained objects */ |
| 284 | inquiry tp_clear; |
| 285 | |
Fred Drake | d55657b | 2001-08-15 18:32:33 +0000 | [diff] [blame] | 286 | /* Assigned meaning in release 2.1 */ |
Guido van Rossum | 5f284ce | 2001-01-17 15:20:39 +0000 | [diff] [blame] | 287 | /* rich comparisons */ |
| 288 | richcmpfunc tp_richcompare; |
| 289 | |
Fred Drake | 41deb1e | 2001-02-01 05:27:45 +0000 | [diff] [blame] | 290 | /* weak reference enabler */ |
Martin v. Löwis | 97c65a8 | 2006-02-16 14:24:38 +0000 | [diff] [blame] | 291 | Py_ssize_t tp_weaklistoffset; |
Guido van Rossum | a9c2d7a | 1998-04-23 19:16:44 +0000 | [diff] [blame] | 292 | |
Guido van Rossum | 59d1d2b | 2001-04-20 19:13:02 +0000 | [diff] [blame] | 293 | /* Iterators */ |
| 294 | getiterfunc tp_iter; |
Guido van Rossum | 213c7a6 | 2001-04-23 14:08:49 +0000 | [diff] [blame] | 295 | iternextfunc tp_iternext; |
Guido van Rossum | 59d1d2b | 2001-04-20 19:13:02 +0000 | [diff] [blame] | 296 | |
Tim Peters | 6d6c1a3 | 2001-08-02 04:15:00 +0000 | [diff] [blame] | 297 | /* Attribute descriptor and subclassing stuff */ |
| 298 | struct PyMethodDef *tp_methods; |
Guido van Rossum | 6f79937 | 2001-09-20 20:46:19 +0000 | [diff] [blame] | 299 | struct PyMemberDef *tp_members; |
Guido van Rossum | 32d34c8 | 2001-09-20 21:45:26 +0000 | [diff] [blame] | 300 | struct PyGetSetDef *tp_getset; |
Tim Peters | 6d6c1a3 | 2001-08-02 04:15:00 +0000 | [diff] [blame] | 301 | struct _typeobject *tp_base; |
| 302 | PyObject *tp_dict; |
| 303 | descrgetfunc tp_descr_get; |
| 304 | descrsetfunc tp_descr_set; |
Martin v. Löwis | 97c65a8 | 2006-02-16 14:24:38 +0000 | [diff] [blame] | 305 | Py_ssize_t tp_dictoffset; |
Tim Peters | 6d6c1a3 | 2001-08-02 04:15:00 +0000 | [diff] [blame] | 306 | initproc tp_init; |
| 307 | allocfunc tp_alloc; |
| 308 | newfunc tp_new; |
Neil Schemenauer | f6d1ea1 | 2002-04-12 01:57:06 +0000 | [diff] [blame] | 309 | freefunc tp_free; /* Low-level free-memory routine */ |
Guido van Rossum | 048eb75 | 2001-10-02 21:24:57 +0000 | [diff] [blame] | 310 | inquiry tp_is_gc; /* For PyObject_IS_GC */ |
Tim Peters | 6d6c1a3 | 2001-08-02 04:15:00 +0000 | [diff] [blame] | 311 | PyObject *tp_bases; |
| 312 | PyObject *tp_mro; /* method resolution order */ |
Guido van Rossum | 687ae00 | 2001-10-15 22:03:32 +0000 | [diff] [blame] | 313 | PyObject *tp_cache; |
Guido van Rossum | 1c45073 | 2001-10-08 15:18:27 +0000 | [diff] [blame] | 314 | PyObject *tp_subclasses; |
| 315 | PyObject *tp_weaklist; |
Guido van Rossum | febd61d | 2002-08-08 20:55:20 +0000 | [diff] [blame] | 316 | destructor tp_del; |
Tim Peters | 6d6c1a3 | 2001-08-02 04:15:00 +0000 | [diff] [blame] | 317 | |
Sjoerd Mullender | a9c3c22 | 1993-10-11 12:54:31 +0000 | [diff] [blame] | 318 | #ifdef COUNT_ALLOCS |
Guido van Rossum | 59d1d2b | 2001-04-20 19:13:02 +0000 | [diff] [blame] | 319 | /* these must be last and never explicitly initialized */ |
Martin v. Löwis | e36dce6 | 2006-03-01 04:02:43 +0000 | [diff] [blame] | 320 | Py_ssize_t tp_allocs; |
| 321 | Py_ssize_t tp_frees; |
| 322 | Py_ssize_t tp_maxalloc; |
Thomas Wouters | 49fd7fa | 2006-04-21 10:40:58 +0000 | [diff] [blame] | 323 | struct _typeobject *tp_prev; |
Sjoerd Mullender | a9c3c22 | 1993-10-11 12:54:31 +0000 | [diff] [blame] | 324 | struct _typeobject *tp_next; |
| 325 | #endif |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 326 | } PyTypeObject; |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 327 | |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 328 | |
Guido van Rossum | e5c691a | 2003-03-07 15:13:17 +0000 | [diff] [blame] | 329 | /* The *real* layout of a type object when allocated on the heap */ |
| 330 | typedef struct _heaptypeobject { |
| 331 | /* Note: there's a dependency on the order of these members |
| 332 | in slotptr() in typeobject.c . */ |
Georg Brandl | c255c7b | 2006-02-20 22:27:28 +0000 | [diff] [blame] | 333 | PyTypeObject ht_type; |
Guido van Rossum | e5c691a | 2003-03-07 15:13:17 +0000 | [diff] [blame] | 334 | PyNumberMethods as_number; |
| 335 | PyMappingMethods as_mapping; |
| 336 | PySequenceMethods as_sequence; /* as_sequence comes after as_mapping, |
| 337 | so that the mapping wins when both |
| 338 | the mapping and the sequence define |
| 339 | a given operator (e.g. __getitem__). |
| 340 | see add_operators() in typeobject.c . */ |
| 341 | PyBufferProcs as_buffer; |
Georg Brandl | c255c7b | 2006-02-20 22:27:28 +0000 | [diff] [blame] | 342 | PyObject *ht_name, *ht_slots; |
Guido van Rossum | e5c691a | 2003-03-07 15:13:17 +0000 | [diff] [blame] | 343 | /* here are optional user slots, followed by the members. */ |
| 344 | } PyHeapTypeObject; |
| 345 | |
| 346 | /* access macro to the members which are floating "behind" the object */ |
| 347 | #define PyHeapType_GET_MEMBERS(etype) \ |
Georg Brandl | c255c7b | 2006-02-20 22:27:28 +0000 | [diff] [blame] | 348 | ((PyMemberDef *)(((char *)etype) + (etype)->ht_type.ob_type->tp_basicsize)) |
Guido van Rossum | e5c691a | 2003-03-07 15:13:17 +0000 | [diff] [blame] | 349 | |
| 350 | |
Tim Peters | 6d6c1a3 | 2001-08-02 04:15:00 +0000 | [diff] [blame] | 351 | /* Generic type check */ |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 352 | PyAPI_FUNC(int) PyType_IsSubtype(PyTypeObject *, PyTypeObject *); |
Tim Peters | 6d6c1a3 | 2001-08-02 04:15:00 +0000 | [diff] [blame] | 353 | #define PyObject_TypeCheck(ob, tp) \ |
| 354 | ((ob)->ob_type == (tp) || PyType_IsSubtype((ob)->ob_type, (tp))) |
| 355 | |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 356 | PyAPI_DATA(PyTypeObject) PyType_Type; /* built-in 'type' */ |
| 357 | PyAPI_DATA(PyTypeObject) PyBaseObject_Type; /* built-in 'object' */ |
| 358 | PyAPI_DATA(PyTypeObject) PySuper_Type; /* built-in 'super' */ |
Tim Peters | 6d6c1a3 | 2001-08-02 04:15:00 +0000 | [diff] [blame] | 359 | |
| 360 | #define PyType_Check(op) PyObject_TypeCheck(op, &PyType_Type) |
Tim Peters | 3abca12 | 2001-10-27 19:37:48 +0000 | [diff] [blame] | 361 | #define PyType_CheckExact(op) ((op)->ob_type == &PyType_Type) |
Tim Peters | 6d6c1a3 | 2001-08-02 04:15:00 +0000 | [diff] [blame] | 362 | |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 363 | PyAPI_FUNC(int) PyType_Ready(PyTypeObject *); |
Martin v. Löwis | 18e1655 | 2006-02-15 17:27:45 +0000 | [diff] [blame] | 364 | PyAPI_FUNC(PyObject *) PyType_GenericAlloc(PyTypeObject *, Py_ssize_t); |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 365 | PyAPI_FUNC(PyObject *) PyType_GenericNew(PyTypeObject *, |
Tim Peters | 6d6c1a3 | 2001-08-02 04:15:00 +0000 | [diff] [blame] | 366 | PyObject *, PyObject *); |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 367 | PyAPI_FUNC(PyObject *) _PyType_Lookup(PyTypeObject *, PyObject *); |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 368 | |
Guido van Rossum | 3f5da24 | 1990-12-20 15:06:42 +0000 | [diff] [blame] | 369 | /* Generic operations on objects */ |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 370 | PyAPI_FUNC(int) PyObject_Print(PyObject *, FILE *, int); |
Guido van Rossum | 3893815 | 2006-08-21 23:36:26 +0000 | [diff] [blame] | 371 | PyAPI_FUNC(void) _Py_Break(void); |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 372 | PyAPI_FUNC(void) _PyObject_Dump(PyObject *); |
| 373 | PyAPI_FUNC(PyObject *) PyObject_Repr(PyObject *); |
Neil Schemenauer | cf52c07 | 2005-08-12 17:34:58 +0000 | [diff] [blame] | 374 | PyAPI_FUNC(PyObject *) _PyObject_Str(PyObject *); |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 375 | PyAPI_FUNC(PyObject *) PyObject_Str(PyObject *); |
Martin v. Löwis | 339d0f7 | 2001-08-17 18:39:25 +0000 | [diff] [blame] | 376 | #ifdef Py_USING_UNICODE |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 377 | PyAPI_FUNC(PyObject *) PyObject_Unicode(PyObject *); |
Martin v. Löwis | 339d0f7 | 2001-08-17 18:39:25 +0000 | [diff] [blame] | 378 | #endif |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 379 | PyAPI_FUNC(int) PyObject_Compare(PyObject *, PyObject *); |
| 380 | PyAPI_FUNC(PyObject *) PyObject_RichCompare(PyObject *, PyObject *, int); |
| 381 | PyAPI_FUNC(int) PyObject_RichCompareBool(PyObject *, PyObject *, int); |
Guido van Rossum | 47b9ff6 | 2006-08-24 00:41:19 +0000 | [diff] [blame] | 382 | PyAPI_FUNC(PyObject *) Py_CmpToRich(int op, int cmp); |
Jeremy Hylton | af68c87 | 2005-12-10 18:50:16 +0000 | [diff] [blame] | 383 | PyAPI_FUNC(PyObject *) PyObject_GetAttrString(PyObject *, const char *); |
| 384 | PyAPI_FUNC(int) PyObject_SetAttrString(PyObject *, const char *, PyObject *); |
| 385 | PyAPI_FUNC(int) PyObject_HasAttrString(PyObject *, const char *); |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 386 | PyAPI_FUNC(PyObject *) PyObject_GetAttr(PyObject *, PyObject *); |
| 387 | PyAPI_FUNC(int) PyObject_SetAttr(PyObject *, PyObject *, PyObject *); |
| 388 | PyAPI_FUNC(int) PyObject_HasAttr(PyObject *, PyObject *); |
| 389 | PyAPI_FUNC(PyObject **) _PyObject_GetDictPtr(PyObject *); |
Raymond Hettinger | 1da1dbf | 2003-03-17 19:46:11 +0000 | [diff] [blame] | 390 | PyAPI_FUNC(PyObject *) PyObject_SelfIter(PyObject *); |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 391 | PyAPI_FUNC(PyObject *) PyObject_GenericGetAttr(PyObject *, PyObject *); |
| 392 | PyAPI_FUNC(int) PyObject_GenericSetAttr(PyObject *, |
Tim Peters | 6d6c1a3 | 2001-08-02 04:15:00 +0000 | [diff] [blame] | 393 | PyObject *, PyObject *); |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 394 | PyAPI_FUNC(long) PyObject_Hash(PyObject *); |
| 395 | PyAPI_FUNC(int) PyObject_IsTrue(PyObject *); |
| 396 | PyAPI_FUNC(int) PyObject_Not(PyObject *); |
| 397 | PyAPI_FUNC(int) PyCallable_Check(PyObject *); |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 398 | |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 399 | PyAPI_FUNC(void) PyObject_ClearWeakRefs(PyObject *); |
Fred Drake | 41deb1e | 2001-02-01 05:27:45 +0000 | [diff] [blame] | 400 | |
Guido van Rossum | ab3b034 | 2001-09-18 20:38:53 +0000 | [diff] [blame] | 401 | /* A slot function whose address we need to compare */ |
| 402 | extern int _PyObject_SlotCompare(PyObject *, PyObject *); |
| 403 | |
| 404 | |
Tim Peters | 7eea37e | 2001-09-04 22:08:56 +0000 | [diff] [blame] | 405 | /* PyObject_Dir(obj) acts like Python __builtin__.dir(obj), returning a |
| 406 | list of strings. PyObject_Dir(NULL) is like __builtin__.dir(), |
| 407 | returning the names of the current locals. In this case, if there are |
| 408 | no current locals, NULL is returned, and PyErr_Occurred() is false. |
| 409 | */ |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 410 | PyAPI_FUNC(PyObject *) PyObject_Dir(PyObject *); |
Tim Peters | 7eea37e | 2001-09-04 22:08:56 +0000 | [diff] [blame] | 411 | |
| 412 | |
Guido van Rossum | 26d4ac3 | 1998-04-10 22:32:24 +0000 | [diff] [blame] | 413 | /* Helpers for printing recursive container types */ |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 414 | PyAPI_FUNC(int) Py_ReprEnter(PyObject *); |
| 415 | PyAPI_FUNC(void) Py_ReprLeave(PyObject *); |
Guido van Rossum | 26d4ac3 | 1998-04-10 22:32:24 +0000 | [diff] [blame] | 416 | |
Fred Drake | 13634cf | 2000-06-29 19:17:04 +0000 | [diff] [blame] | 417 | /* Helpers for hash functions */ |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 418 | PyAPI_FUNC(long) _Py_HashDouble(double); |
| 419 | PyAPI_FUNC(long) _Py_HashPointer(void*); |
Fred Drake | 13634cf | 2000-06-29 19:17:04 +0000 | [diff] [blame] | 420 | |
Jeremy Hylton | 483638c | 2001-02-01 20:20:45 +0000 | [diff] [blame] | 421 | /* Helper for passing objects to printf and the like */ |
| 422 | #define PyObject_REPR(obj) PyString_AS_STRING(PyObject_Repr(obj)) |
| 423 | |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 424 | /* Flag bits for printing: */ |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 425 | #define Py_PRINT_RAW 1 /* No string quotes etc. */ |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 426 | |
| 427 | /* |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 428 | `Type flags (tp_flags) |
Guido van Rossum | 36eef3c | 1998-10-08 02:10:56 +0000 | [diff] [blame] | 429 | |
| 430 | These flags are used to extend the type structure in a backwards-compatible |
| 431 | fashion. Extensions can use the flags to indicate (and test) when a given |
| 432 | type structure contains a new feature. The Python core will use these when |
| 433 | introducing new functionality between major revisions (to avoid mid-version |
| 434 | changes in the PYTHON_API_VERSION). |
| 435 | |
| 436 | Arbitration of the flag bit positions will need to be coordinated among |
| 437 | all extension writers who publically release their extensions (this will |
| 438 | be fewer than you might expect!).. |
| 439 | |
Guido van Rossum | 3cf5b1e | 2006-07-27 21:53:35 +0000 | [diff] [blame] | 440 | Most flags were removed as of Python 3.0 to make room for new flags. (Some |
| 441 | flags are not for backwards compatibility but to indicate the presence of an |
| 442 | optional feature; these flags remain of course.) |
Guido van Rossum | 36eef3c | 1998-10-08 02:10:56 +0000 | [diff] [blame] | 443 | |
| 444 | Type definitions should use Py_TPFLAGS_DEFAULT for their tp_flags value. |
| 445 | |
| 446 | Code can use PyType_HasFeature(type_ob, flag_value) to test whether the |
| 447 | given type object has a specified feature. |
Guido van Rossum | 36eef3c | 1998-10-08 02:10:56 +0000 | [diff] [blame] | 448 | */ |
| 449 | |
Tim Peters | 6d6c1a3 | 2001-08-02 04:15:00 +0000 | [diff] [blame] | 450 | /* Set if the type object is dynamically allocated */ |
| 451 | #define Py_TPFLAGS_HEAPTYPE (1L<<9) |
| 452 | |
| 453 | /* Set if the type allows subclassing */ |
| 454 | #define Py_TPFLAGS_BASETYPE (1L<<10) |
| 455 | |
Guido van Rossum | 9b9c972 | 2001-08-10 17:37:02 +0000 | [diff] [blame] | 456 | /* Set if the type is 'ready' -- fully initialized */ |
| 457 | #define Py_TPFLAGS_READY (1L<<12) |
| 458 | |
| 459 | /* Set while the type is being 'readied', to prevent recursive ready calls */ |
| 460 | #define Py_TPFLAGS_READYING (1L<<13) |
| 461 | |
Neil Schemenauer | 31ec142 | 2001-08-29 23:46:35 +0000 | [diff] [blame] | 462 | /* Objects support garbage collection (see objimp.h) */ |
Neil Schemenauer | 31ec142 | 2001-08-29 23:46:35 +0000 | [diff] [blame] | 463 | #define Py_TPFLAGS_HAVE_GC (1L<<14) |
Neil Schemenauer | 31ec142 | 2001-08-29 23:46:35 +0000 | [diff] [blame] | 464 | |
Guido van Rossum | 38fff8c | 2006-03-07 18:50:55 +0000 | [diff] [blame] | 465 | /* These two bits are preserved for Stackless Python, next after this is 17 */ |
Christian Tismer | 6695ba8 | 2003-05-20 15:14:31 +0000 | [diff] [blame] | 466 | #ifdef STACKLESS |
Christian Tismer | 661a9e3 | 2003-05-23 12:47:36 +0000 | [diff] [blame] | 467 | #define Py_TPFLAGS_HAVE_STACKLESS_EXTENSION (3L<<15) |
Christian Tismer | 6695ba8 | 2003-05-20 15:14:31 +0000 | [diff] [blame] | 468 | #else |
Christian Tismer | c26ff41 | 2003-05-23 03:33:35 +0000 | [diff] [blame] | 469 | #define Py_TPFLAGS_HAVE_STACKLESS_EXTENSION 0 |
Christian Tismer | 6695ba8 | 2003-05-20 15:14:31 +0000 | [diff] [blame] | 470 | #endif |
| 471 | |
Guido van Rossum | bacca54 | 2001-01-24 22:13:48 +0000 | [diff] [blame] | 472 | #define Py_TPFLAGS_DEFAULT ( \ |
Christian Tismer | c26ff41 | 2003-05-23 03:33:35 +0000 | [diff] [blame] | 473 | Py_TPFLAGS_HAVE_STACKLESS_EXTENSION | \ |
Guido van Rossum | bacca54 | 2001-01-24 22:13:48 +0000 | [diff] [blame] | 474 | 0) |
Guido van Rossum | 36eef3c | 1998-10-08 02:10:56 +0000 | [diff] [blame] | 475 | |
| 476 | #define PyType_HasFeature(t,f) (((t)->tp_flags & (f)) != 0) |
| 477 | |
| 478 | |
| 479 | /* |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 480 | The macros Py_INCREF(op) and Py_DECREF(op) are used to increment or decrement |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 481 | reference counts. Py_DECREF calls the object's deallocator function when |
| 482 | the refcount falls to 0; for |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 483 | objects that don't contain references to other objects or heap memory |
| 484 | this can be the standard function free(). Both macros can be used |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 485 | wherever a void expression is allowed. The argument must not be a |
| 486 | NIL pointer. If it may be NIL, use Py_XINCREF/Py_XDECREF instead. |
| 487 | The macro _Py_NewReference(op) initialize reference counts to 1, and |
| 488 | in special builds (Py_REF_DEBUG, Py_TRACE_REFS) performs additional |
| 489 | bookkeeping appropriate to the special build. |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 490 | |
| 491 | We assume that the reference count field can never overflow; this can |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 492 | be proven when the size of the field is the same as the pointer size, so |
| 493 | we ignore the possibility. Provided a C int is at least 32 bits (which |
| 494 | is implicitly assumed in many parts of this code), that's enough for |
| 495 | about 2**31 references to an object. |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 496 | |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 497 | XXX The following became out of date in Python 2.2, but I'm not sure |
| 498 | XXX what the full truth is now. Certainly, heap-allocated type objects |
| 499 | XXX can and should be deallocated. |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 500 | Type objects should never be deallocated; the type pointer in an object |
| 501 | is not considered to be a reference to the type object, to save |
| 502 | complications in the deallocation function. (This is actually a |
| 503 | decision that's up to the implementer of each new type so if you want, |
| 504 | you can count such references to the type object.) |
| 505 | |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 506 | *** WARNING*** The Py_DECREF macro must have a side-effect-free argument |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 507 | since it may evaluate its argument multiple times. (The alternative |
| 508 | would be to mace it a proper function or assign it to a global temporary |
| 509 | variable first, both of which are slower; and in a multi-threaded |
| 510 | environment the global variable trick is not safe.) |
| 511 | */ |
| 512 | |
Tim Peters | 3459251 | 2002-07-11 06:23:50 +0000 | [diff] [blame] | 513 | /* First define a pile of simple helper macros, one set per special |
| 514 | * build symbol. These either expand to the obvious things, or to |
| 515 | * nothing at all when the special mode isn't in effect. The main |
| 516 | * macros can later be defined just once then, yet expand to different |
| 517 | * things depending on which special build options are and aren't in effect. |
| 518 | * Trust me <wink>: while painful, this is 20x easier to understand than, |
| 519 | * e.g, defining _Py_NewReference five different times in a maze of nested |
| 520 | * #ifdefs (we used to do that -- it was impenetrable). |
| 521 | */ |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 522 | #ifdef Py_REF_DEBUG |
Neal Norwitz | 4281cef | 2006-03-04 19:58:13 +0000 | [diff] [blame] | 523 | PyAPI_DATA(Py_ssize_t) _Py_RefTotal; |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 524 | PyAPI_FUNC(void) _Py_NegativeRefcount(const char *fname, |
Tim Peters | 7c321a8 | 2002-07-09 02:57:01 +0000 | [diff] [blame] | 525 | int lineno, PyObject *op); |
Thomas Wouters | 49fd7fa | 2006-04-21 10:40:58 +0000 | [diff] [blame] | 526 | PyAPI_FUNC(PyObject *) _PyDict_Dummy(void); |
| 527 | PyAPI_FUNC(PyObject *) _PySet_Dummy(void); |
| 528 | PyAPI_FUNC(Py_ssize_t) _Py_GetRefTotal(void); |
Tim Peters | 3459251 | 2002-07-11 06:23:50 +0000 | [diff] [blame] | 529 | #define _Py_INC_REFTOTAL _Py_RefTotal++ |
| 530 | #define _Py_DEC_REFTOTAL _Py_RefTotal-- |
| 531 | #define _Py_REF_DEBUG_COMMA , |
| 532 | #define _Py_CHECK_REFCNT(OP) \ |
Tim Peters | 7c321a8 | 2002-07-09 02:57:01 +0000 | [diff] [blame] | 533 | { if ((OP)->ob_refcnt < 0) \ |
| 534 | _Py_NegativeRefcount(__FILE__, __LINE__, \ |
| 535 | (PyObject *)(OP)); \ |
| 536 | } |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 537 | #else |
Tim Peters | 3459251 | 2002-07-11 06:23:50 +0000 | [diff] [blame] | 538 | #define _Py_INC_REFTOTAL |
| 539 | #define _Py_DEC_REFTOTAL |
| 540 | #define _Py_REF_DEBUG_COMMA |
| 541 | #define _Py_CHECK_REFCNT(OP) /* a semicolon */; |
Tim Peters | 57f4ddd | 2002-07-10 06:34:15 +0000 | [diff] [blame] | 542 | #endif /* Py_REF_DEBUG */ |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 543 | |
Sjoerd Mullender | a9c3c22 | 1993-10-11 12:54:31 +0000 | [diff] [blame] | 544 | #ifdef COUNT_ALLOCS |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 545 | PyAPI_FUNC(void) inc_count(PyTypeObject *); |
Thomas Wouters | 49fd7fa | 2006-04-21 10:40:58 +0000 | [diff] [blame] | 546 | PyAPI_FUNC(void) dec_count(PyTypeObject *); |
Tim Peters | 3459251 | 2002-07-11 06:23:50 +0000 | [diff] [blame] | 547 | #define _Py_INC_TPALLOCS(OP) inc_count((OP)->ob_type) |
Thomas Wouters | 49fd7fa | 2006-04-21 10:40:58 +0000 | [diff] [blame] | 548 | #define _Py_INC_TPFREES(OP) dec_count((OP)->ob_type) |
Tim Peters | 3459251 | 2002-07-11 06:23:50 +0000 | [diff] [blame] | 549 | #define _Py_DEC_TPFREES(OP) (OP)->ob_type->tp_frees-- |
| 550 | #define _Py_COUNT_ALLOCS_COMMA , |
Sjoerd Mullender | a9c3c22 | 1993-10-11 12:54:31 +0000 | [diff] [blame] | 551 | #else |
Tim Peters | 3459251 | 2002-07-11 06:23:50 +0000 | [diff] [blame] | 552 | #define _Py_INC_TPALLOCS(OP) |
| 553 | #define _Py_INC_TPFREES(OP) |
| 554 | #define _Py_DEC_TPFREES(OP) |
| 555 | #define _Py_COUNT_ALLOCS_COMMA |
Tim Peters | 57f4ddd | 2002-07-10 06:34:15 +0000 | [diff] [blame] | 556 | #endif /* COUNT_ALLOCS */ |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 557 | |
| 558 | #ifdef Py_TRACE_REFS |
| 559 | /* Py_TRACE_REFS is such major surgery that we call external routines. */ |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 560 | PyAPI_FUNC(void) _Py_NewReference(PyObject *); |
| 561 | PyAPI_FUNC(void) _Py_ForgetReference(PyObject *); |
| 562 | PyAPI_FUNC(void) _Py_Dealloc(PyObject *); |
| 563 | PyAPI_FUNC(void) _Py_PrintReferences(FILE *); |
Tim Peters | 269b2a6 | 2003-04-17 19:52:29 +0000 | [diff] [blame] | 564 | PyAPI_FUNC(void) _Py_PrintReferenceAddresses(FILE *); |
Tim Peters | 7571a0f | 2003-03-23 17:52:28 +0000 | [diff] [blame] | 565 | PyAPI_FUNC(void) _Py_AddToAllObjects(PyObject *, int force); |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 566 | |
| 567 | #else |
| 568 | /* Without Py_TRACE_REFS, there's little enough to do that we expand code |
| 569 | * inline. |
| 570 | */ |
Tim Peters | 3459251 | 2002-07-11 06:23:50 +0000 | [diff] [blame] | 571 | #define _Py_NewReference(op) ( \ |
| 572 | _Py_INC_TPALLOCS(op) _Py_COUNT_ALLOCS_COMMA \ |
| 573 | _Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA \ |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 574 | (op)->ob_refcnt = 1) |
| 575 | |
Tim Peters | 3459251 | 2002-07-11 06:23:50 +0000 | [diff] [blame] | 576 | #define _Py_ForgetReference(op) _Py_INC_TPFREES(op) |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 577 | |
Tim Peters | 57f4ddd | 2002-07-10 06:34:15 +0000 | [diff] [blame] | 578 | #define _Py_Dealloc(op) ( \ |
Tim Peters | 3459251 | 2002-07-11 06:23:50 +0000 | [diff] [blame] | 579 | _Py_INC_TPFREES(op) _Py_COUNT_ALLOCS_COMMA \ |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 580 | (*(op)->ob_type->tp_dealloc)((PyObject *)(op))) |
Guido van Rossum | 60be1db | 1996-05-22 16:33:22 +0000 | [diff] [blame] | 581 | #endif /* !Py_TRACE_REFS */ |
| 582 | |
Tim Peters | 3459251 | 2002-07-11 06:23:50 +0000 | [diff] [blame] | 583 | #define Py_INCREF(op) ( \ |
| 584 | _Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA \ |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 585 | (op)->ob_refcnt++) |
| 586 | |
Tim Peters | 3459251 | 2002-07-11 06:23:50 +0000 | [diff] [blame] | 587 | #define Py_DECREF(op) \ |
| 588 | if (_Py_DEC_REFTOTAL _Py_REF_DEBUG_COMMA \ |
| 589 | --(op)->ob_refcnt != 0) \ |
| 590 | _Py_CHECK_REFCNT(op) \ |
| 591 | else \ |
Guido van Rossum | 1d529d1 | 1997-08-05 02:30:44 +0000 | [diff] [blame] | 592 | _Py_Dealloc((PyObject *)(op)) |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 593 | |
Thomas Wouters | 49fd7fa | 2006-04-21 10:40:58 +0000 | [diff] [blame] | 594 | /* Safely decref `op` and set `op` to NULL, especially useful in tp_clear |
| 595 | * and tp_dealloc implementatons. |
| 596 | * |
| 597 | * Note that "the obvious" code can be deadly: |
| 598 | * |
| 599 | * Py_XDECREF(op); |
| 600 | * op = NULL; |
| 601 | * |
| 602 | * Typically, `op` is something like self->containee, and `self` is done |
| 603 | * using its `containee` member. In the code sequence above, suppose |
| 604 | * `containee` is non-NULL with a refcount of 1. Its refcount falls to |
| 605 | * 0 on the first line, which can trigger an arbitrary amount of code, |
| 606 | * possibly including finalizers (like __del__ methods or weakref callbacks) |
| 607 | * coded in Python, which in turn can release the GIL and allow other threads |
| 608 | * to run, etc. Such code may even invoke methods of `self` again, or cause |
| 609 | * cyclic gc to trigger, but-- oops! --self->containee still points to the |
| 610 | * object being torn down, and it may be in an insane state while being torn |
| 611 | * down. This has in fact been a rich historic source of miserable (rare & |
| 612 | * hard-to-diagnose) segfaulting (and other) bugs. |
| 613 | * |
| 614 | * The safe way is: |
| 615 | * |
| 616 | * Py_CLEAR(op); |
| 617 | * |
| 618 | * That arranges to set `op` to NULL _before_ decref'ing, so that any code |
| 619 | * triggered as a side-effect of `op` getting torn down no longer believes |
| 620 | * `op` points to a valid object. |
| 621 | * |
| 622 | * There are cases where it's safe to use the naive code, but they're brittle. |
| 623 | * For example, if `op` points to a Python integer, you know that destroying |
| 624 | * one of those can't cause problems -- but in part that relies on that |
| 625 | * Python integers aren't currently weakly referencable. Best practice is |
| 626 | * to use Py_CLEAR() even if you can't think of a reason for why you need to. |
| 627 | */ |
Jim Fulton | 8c5aeaa | 2004-07-14 19:07:35 +0000 | [diff] [blame] | 628 | #define Py_CLEAR(op) \ |
| 629 | do { \ |
| 630 | if (op) { \ |
Raymond Hettinger | 75ccea3 | 2004-09-01 07:02:44 +0000 | [diff] [blame] | 631 | PyObject *tmp = (PyObject *)(op); \ |
Jim Fulton | 8c5aeaa | 2004-07-14 19:07:35 +0000 | [diff] [blame] | 632 | (op) = NULL; \ |
| 633 | Py_DECREF(tmp); \ |
| 634 | } \ |
| 635 | } while (0) |
| 636 | |
Guido van Rossum | 3f5da24 | 1990-12-20 15:06:42 +0000 | [diff] [blame] | 637 | /* Macros to use in case the object pointer may be NULL: */ |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 638 | #define Py_XINCREF(op) if ((op) == NULL) ; else Py_INCREF(op) |
| 639 | #define Py_XDECREF(op) if ((op) == NULL) ; else Py_DECREF(op) |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 640 | |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 641 | /* |
Thomas Heller | 1328b52 | 2004-04-22 17:23:49 +0000 | [diff] [blame] | 642 | These are provided as conveniences to Python runtime embedders, so that |
| 643 | they can have object code that is not dependent on Python compilation flags. |
| 644 | */ |
| 645 | PyAPI_FUNC(void) Py_IncRef(PyObject *); |
| 646 | PyAPI_FUNC(void) Py_DecRef(PyObject *); |
| 647 | |
| 648 | /* |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 649 | _Py_NoneStruct is an object of undefined type which can be used in contexts |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 650 | where NULL (nil) is not suitable (since NULL often means 'error'). |
| 651 | |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 652 | Don't forget to apply Py_INCREF() when returning this value!!! |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 653 | */ |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 654 | PyAPI_DATA(PyObject) _Py_NoneStruct; /* Don't use this directly */ |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 655 | #define Py_None (&_Py_NoneStruct) |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 656 | |
Brett Cannon | d05235e | 2003-10-19 21:19:40 +0000 | [diff] [blame] | 657 | /* Macro for returning Py_None from a function */ |
Tim Peters | 5980ff2 | 2004-07-22 01:46:43 +0000 | [diff] [blame] | 658 | #define Py_RETURN_NONE return Py_INCREF(Py_None), Py_None |
Brett Cannon | d05235e | 2003-10-19 21:19:40 +0000 | [diff] [blame] | 659 | |
Neil Schemenauer | a7ed694 | 2001-01-04 01:31:50 +0000 | [diff] [blame] | 660 | /* |
| 661 | Py_NotImplemented is a singleton used to signal that an operation is |
| 662 | not implemented for a given type combination. |
| 663 | */ |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 664 | PyAPI_DATA(PyObject) _Py_NotImplementedStruct; /* Don't use this directly */ |
Neil Schemenauer | a7ed694 | 2001-01-04 01:31:50 +0000 | [diff] [blame] | 665 | #define Py_NotImplemented (&_Py_NotImplementedStruct) |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 666 | |
Guido van Rossum | 5f284ce | 2001-01-17 15:20:39 +0000 | [diff] [blame] | 667 | /* Rich comparison opcodes */ |
| 668 | #define Py_LT 0 |
| 669 | #define Py_LE 1 |
| 670 | #define Py_EQ 2 |
| 671 | #define Py_NE 3 |
| 672 | #define Py_GT 4 |
| 673 | #define Py_GE 5 |
| 674 | |
Tim Peters | f4aca75 | 2004-09-23 02:39:37 +0000 | [diff] [blame] | 675 | /* Maps Py_LT to Py_GT, ..., Py_GE to Py_LE. |
| 676 | * Defined in object.c. |
| 677 | */ |
| 678 | PyAPI_DATA(int) _Py_SwappedOp[]; |
| 679 | |
Guido van Rossum | b6775db | 1994-08-01 11:34:53 +0000 | [diff] [blame] | 680 | |
| 681 | /* |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 682 | More conventions |
| 683 | ================ |
| 684 | |
| 685 | Argument Checking |
| 686 | ----------------- |
| 687 | |
| 688 | Functions that take objects as arguments normally don't check for nil |
| 689 | arguments, but they do check the type of the argument, and return an |
| 690 | error if the function doesn't apply to the type. |
| 691 | |
| 692 | Failure Modes |
| 693 | ------------- |
| 694 | |
| 695 | Functions may fail for a variety of reasons, including running out of |
Guido van Rossum | 3f5da24 | 1990-12-20 15:06:42 +0000 | [diff] [blame] | 696 | memory. This is communicated to the caller in two ways: an error string |
| 697 | is set (see errors.h), and the function result differs: functions that |
| 698 | normally return a pointer return NULL for failure, functions returning |
| 699 | an integer return -1 (which could be a legal return value too!), and |
| 700 | other functions return 0 for success and -1 for failure. |
Tim Peters | 4be93d0 | 2002-07-07 19:59:50 +0000 | [diff] [blame] | 701 | Callers should always check for errors before using the result. If |
| 702 | an error was set, the caller must either explicitly clear it, or pass |
| 703 | the error on to its caller. |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 704 | |
| 705 | Reference Counts |
| 706 | ---------------- |
| 707 | |
| 708 | It takes a while to get used to the proper usage of reference counts. |
| 709 | |
| 710 | Functions that create an object set the reference count to 1; such new |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 711 | objects must be stored somewhere or destroyed again with Py_DECREF(). |
Alex Martelli | 721b776 | 2003-11-09 16:38:39 +0000 | [diff] [blame] | 712 | Some functions that 'store' objects, such as PyTuple_SetItem() and |
| 713 | PyList_SetItem(), |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 714 | don't increment the reference count of the object, since the most |
| 715 | frequent use is to store a fresh object. Functions that 'retrieve' |
Alex Martelli | 721b776 | 2003-11-09 16:38:39 +0000 | [diff] [blame] | 716 | objects, such as PyTuple_GetItem() and PyDict_GetItemString(), also |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 717 | don't increment |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 718 | the reference count, since most frequently the object is only looked at |
| 719 | quickly. Thus, to retrieve an object and store it again, the caller |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 720 | must call Py_INCREF() explicitly. |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 721 | |
Alex Martelli | 721b776 | 2003-11-09 16:38:39 +0000 | [diff] [blame] | 722 | NOTE: functions that 'consume' a reference count, like |
| 723 | PyList_SetItem(), consume the reference even if the object wasn't |
| 724 | successfully stored, to simplify error handling. |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 725 | |
| 726 | It seems attractive to make other functions that take an object as |
Alex Martelli | 721b776 | 2003-11-09 16:38:39 +0000 | [diff] [blame] | 727 | argument consume a reference count; however, this may quickly get |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 728 | confusing (even the current practice is already confusing). Consider |
Guido van Rossum | caa6380 | 1995-01-12 11:45:45 +0000 | [diff] [blame] | 729 | it carefully, it may save lots of calls to Py_INCREF() and Py_DECREF() at |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 730 | times. |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 731 | */ |
Guido van Rossum | a330996 | 1993-07-28 09:05:47 +0000 | [diff] [blame] | 732 | |
Guido van Rossum | d724b23 | 2000-03-13 16:01:29 +0000 | [diff] [blame] | 733 | |
Tim Peters | 803526b | 2002-07-07 05:13:56 +0000 | [diff] [blame] | 734 | /* Trashcan mechanism, thanks to Christian Tismer. |
Guido van Rossum | d724b23 | 2000-03-13 16:01:29 +0000 | [diff] [blame] | 735 | |
Tim Peters | 803526b | 2002-07-07 05:13:56 +0000 | [diff] [blame] | 736 | When deallocating a container object, it's possible to trigger an unbounded |
| 737 | chain of deallocations, as each Py_DECREF in turn drops the refcount on "the |
| 738 | next" object in the chain to 0. This can easily lead to stack faults, and |
| 739 | especially in threads (which typically have less stack space to work with). |
Guido van Rossum | d724b23 | 2000-03-13 16:01:29 +0000 | [diff] [blame] | 740 | |
Tim Peters | 803526b | 2002-07-07 05:13:56 +0000 | [diff] [blame] | 741 | A container object that participates in cyclic gc can avoid this by |
| 742 | bracketing the body of its tp_dealloc function with a pair of macros: |
Guido van Rossum | e92e610 | 2000-04-24 15:40:53 +0000 | [diff] [blame] | 743 | |
Tim Peters | 803526b | 2002-07-07 05:13:56 +0000 | [diff] [blame] | 744 | static void |
| 745 | mytype_dealloc(mytype *p) |
| 746 | { |
| 747 | ... declarations go here ... |
| 748 | |
| 749 | PyObject_GC_UnTrack(p); // must untrack first |
| 750 | Py_TRASHCAN_SAFE_BEGIN(p) |
| 751 | ... The body of the deallocator goes here, including all calls ... |
| 752 | ... to Py_DECREF on contained objects. ... |
| 753 | Py_TRASHCAN_SAFE_END(p) |
| 754 | } |
| 755 | |
Tim Peters | 808eb59 | 2002-08-07 20:53:05 +0000 | [diff] [blame] | 756 | CAUTION: Never return from the middle of the body! If the body needs to |
| 757 | "get out early", put a label immediately before the Py_TRASHCAN_SAFE_END |
| 758 | call, and goto it. Else the call-depth counter (see below) will stay |
| 759 | above 0 forever, and the trashcan will never get emptied. |
| 760 | |
Tim Peters | 803526b | 2002-07-07 05:13:56 +0000 | [diff] [blame] | 761 | How it works: The BEGIN macro increments a call-depth counter. So long |
| 762 | as this counter is small, the body of the deallocator is run directly without |
| 763 | further ado. But if the counter gets large, it instead adds p to a list of |
| 764 | objects to be deallocated later, skips the body of the deallocator, and |
| 765 | resumes execution after the END macro. The tp_dealloc routine then returns |
| 766 | without deallocating anything (and so unbounded call-stack depth is avoided). |
| 767 | |
| 768 | When the call stack finishes unwinding again, code generated by the END macro |
| 769 | notices this, and calls another routine to deallocate all the objects that |
| 770 | may have been added to the list of deferred deallocations. In effect, a |
| 771 | chain of N deallocations is broken into N / PyTrash_UNWIND_LEVEL pieces, |
| 772 | with the call stack never exceeding a depth of PyTrash_UNWIND_LEVEL. |
Guido van Rossum | d724b23 | 2000-03-13 16:01:29 +0000 | [diff] [blame] | 773 | */ |
| 774 | |
Mark Hammond | a290527 | 2002-07-29 13:42:14 +0000 | [diff] [blame] | 775 | PyAPI_FUNC(void) _PyTrash_deposit_object(PyObject*); |
| 776 | PyAPI_FUNC(void) _PyTrash_destroy_chain(void); |
| 777 | PyAPI_DATA(int) _PyTrash_delete_nesting; |
| 778 | PyAPI_DATA(PyObject *) _PyTrash_delete_later; |
Tim Peters | 803526b | 2002-07-07 05:13:56 +0000 | [diff] [blame] | 779 | |
Guido van Rossum | d724b23 | 2000-03-13 16:01:29 +0000 | [diff] [blame] | 780 | #define PyTrash_UNWIND_LEVEL 50 |
| 781 | |
| 782 | #define Py_TRASHCAN_SAFE_BEGIN(op) \ |
Tim Peters | 803526b | 2002-07-07 05:13:56 +0000 | [diff] [blame] | 783 | if (_PyTrash_delete_nesting < PyTrash_UNWIND_LEVEL) { \ |
| 784 | ++_PyTrash_delete_nesting; |
| 785 | /* The body of the deallocator is here. */ |
Guido van Rossum | d724b23 | 2000-03-13 16:01:29 +0000 | [diff] [blame] | 786 | #define Py_TRASHCAN_SAFE_END(op) \ |
Guido van Rossum | d724b23 | 2000-03-13 16:01:29 +0000 | [diff] [blame] | 787 | --_PyTrash_delete_nesting; \ |
| 788 | if (_PyTrash_delete_later && _PyTrash_delete_nesting <= 0) \ |
Guido van Rossum | e92e610 | 2000-04-24 15:40:53 +0000 | [diff] [blame] | 789 | _PyTrash_destroy_chain(); \ |
Guido van Rossum | d724b23 | 2000-03-13 16:01:29 +0000 | [diff] [blame] | 790 | } \ |
Tim Peters | 803526b | 2002-07-07 05:13:56 +0000 | [diff] [blame] | 791 | else \ |
| 792 | _PyTrash_deposit_object((PyObject*)op); |
Guido van Rossum | e92e610 | 2000-04-24 15:40:53 +0000 | [diff] [blame] | 793 | |
Guido van Rossum | a330996 | 1993-07-28 09:05:47 +0000 | [diff] [blame] | 794 | #ifdef __cplusplus |
| 795 | } |
| 796 | #endif |
| 797 | #endif /* !Py_OBJECT_H */ |