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783 lines
29 KiB
783 lines
29 KiB
#ifndef Py_OBJECT_H |
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#define Py_OBJECT_H |
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#ifdef __cplusplus |
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extern "C" { |
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#endif |
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|
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/* Object and type object interface */ |
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|
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/* |
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Objects are structures allocated on the heap. Special rules apply to |
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the use of objects to ensure they are properly garbage-collected. |
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Objects are never allocated statically or on the stack; they must be |
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accessed through special macros and functions only. (Type objects are |
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exceptions to the first rule; the standard types are represented by |
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statically initialized type objects, although work on type/class unification |
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for Python 2.2 made it possible to have heap-allocated type objects too). |
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|
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An object has a 'reference count' that is increased or decreased when a |
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pointer to the object is copied or deleted; when the reference count |
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reaches zero there are no references to the object left and it can be |
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removed from the heap. |
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|
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An object has a 'type' that determines what it represents and what kind |
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of data it contains. An object's type is fixed when it is created. |
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Types themselves are represented as objects; an object contains a |
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pointer to the corresponding type object. The type itself has a type |
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pointer pointing to the object representing the type 'type', which |
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contains a pointer to itself!). |
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|
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Objects do not float around in memory; once allocated an object keeps |
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the same size and address. Objects that must hold variable-size data |
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can contain pointers to variable-size parts of the object. Not all |
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objects of the same type have the same size; but the size cannot change |
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after allocation. (These restrictions are made so a reference to an |
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object can be simply a pointer -- moving an object would require |
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updating all the pointers, and changing an object's size would require |
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moving it if there was another object right next to it.) |
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|
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Objects are always accessed through pointers of the type 'PyObject *'. |
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The type 'PyObject' is a structure that only contains the reference count |
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and the type pointer. The actual memory allocated for an object |
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contains other data that can only be accessed after casting the pointer |
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to a pointer to a longer structure type. This longer type must start |
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with the reference count and type fields; the macro PyObject_HEAD should be |
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used for this (to accommodate for future changes). The implementation |
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of a particular object type can cast the object pointer to the proper |
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type and back. |
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A standard interface exists for objects that contain an array of items |
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whose size is determined when the object is allocated. |
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*/ |
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/* Py_DEBUG implies Py_TRACE_REFS. */ |
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#if defined(Py_DEBUG) && !defined(Py_TRACE_REFS) |
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#define Py_TRACE_REFS |
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#endif |
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/* Py_TRACE_REFS implies Py_REF_DEBUG. */ |
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#if defined(Py_TRACE_REFS) && !defined(Py_REF_DEBUG) |
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#define Py_REF_DEBUG |
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#endif |
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#ifdef Py_TRACE_REFS |
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/* Define pointers to support a doubly-linked list of all live heap objects. */ |
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#define _PyObject_HEAD_EXTRA \ |
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struct _object *_ob_next; \ |
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struct _object *_ob_prev; |
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#define _PyObject_EXTRA_INIT 0, 0, |
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#else |
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#define _PyObject_HEAD_EXTRA |
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#define _PyObject_EXTRA_INIT |
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#endif |
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|
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/* PyObject_HEAD defines the initial segment of every PyObject. */ |
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#define PyObject_HEAD \ |
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_PyObject_HEAD_EXTRA \ |
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int ob_refcnt; \ |
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struct _typeobject *ob_type; |
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|
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#define PyObject_HEAD_INIT(type) \ |
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_PyObject_EXTRA_INIT \ |
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1, type, |
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|
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/* PyObject_VAR_HEAD defines the initial segment of all variable-size |
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* container objects. These end with a declaration of an array with 1 |
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* element, but enough space is malloc'ed so that the array actually |
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* has room for ob_size elements. Note that ob_size is an element count, |
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* not necessarily a byte count. |
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*/ |
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#define PyObject_VAR_HEAD \ |
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PyObject_HEAD \ |
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int ob_size; /* Number of items in variable part */ |
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|
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/* Nothing is actually declared to be a PyObject, but every pointer to |
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* a Python object can be cast to a PyObject*. This is inheritance built |
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* by hand. Similarly every pointer to a variable-size Python object can, |
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* in addition, be cast to PyVarObject*. |
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*/ |
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typedef struct _object { |
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PyObject_HEAD |
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} PyObject; |
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typedef struct { |
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PyObject_VAR_HEAD |
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} PyVarObject; |
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/* |
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Type objects contain a string containing the type name (to help somewhat |
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in debugging), the allocation parameters (see PyObject_New() and |
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PyObject_NewVar()), |
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and methods for accessing objects of the type. Methods are optional, a |
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nil pointer meaning that particular kind of access is not available for |
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this type. The Py_DECREF() macro uses the tp_dealloc method without |
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checking for a nil pointer; it should always be implemented except if |
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the implementation can guarantee that the reference count will never |
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reach zero (e.g., for statically allocated type objects). |
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|
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NB: the methods for certain type groups are now contained in separate |
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method blocks. |
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*/ |
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typedef PyObject * (*unaryfunc)(PyObject *); |
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typedef PyObject * (*binaryfunc)(PyObject *, PyObject *); |
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typedef PyObject * (*ternaryfunc)(PyObject *, PyObject *, PyObject *); |
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typedef int (*inquiry)(PyObject *); |
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typedef int (*coercion)(PyObject **, PyObject **); |
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typedef PyObject *(*intargfunc)(PyObject *, int); |
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typedef PyObject *(*intintargfunc)(PyObject *, int, int); |
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typedef int(*intobjargproc)(PyObject *, int, PyObject *); |
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typedef int(*intintobjargproc)(PyObject *, int, int, PyObject *); |
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typedef int(*objobjargproc)(PyObject *, PyObject *, PyObject *); |
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typedef int (*getreadbufferproc)(PyObject *, int, void **); |
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typedef int (*getwritebufferproc)(PyObject *, int, void **); |
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typedef int (*getsegcountproc)(PyObject *, int *); |
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typedef int (*getcharbufferproc)(PyObject *, int, const char **); |
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typedef int (*objobjproc)(PyObject *, PyObject *); |
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typedef int (*visitproc)(PyObject *, void *); |
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typedef int (*traverseproc)(PyObject *, visitproc, void *); |
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typedef struct { |
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/* For numbers without flag bit Py_TPFLAGS_CHECKTYPES set, all |
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arguments are guaranteed to be of the object's type (modulo |
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coercion hacks -- i.e. if the type's coercion function |
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returns other types, then these are allowed as well). Numbers that |
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have the Py_TPFLAGS_CHECKTYPES flag bit set should check *both* |
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arguments for proper type and implement the necessary conversions |
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in the slot functions themselves. */ |
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|
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binaryfunc nb_add; |
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binaryfunc nb_subtract; |
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binaryfunc nb_multiply; |
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binaryfunc nb_divide; |
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binaryfunc nb_remainder; |
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binaryfunc nb_divmod; |
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ternaryfunc nb_power; |
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unaryfunc nb_negative; |
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unaryfunc nb_positive; |
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unaryfunc nb_absolute; |
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inquiry nb_nonzero; |
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unaryfunc nb_invert; |
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binaryfunc nb_lshift; |
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binaryfunc nb_rshift; |
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binaryfunc nb_and; |
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binaryfunc nb_xor; |
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binaryfunc nb_or; |
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coercion nb_coerce; |
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unaryfunc nb_int; |
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unaryfunc nb_long; |
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unaryfunc nb_float; |
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unaryfunc nb_oct; |
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unaryfunc nb_hex; |
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/* Added in release 2.0 */ |
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binaryfunc nb_inplace_add; |
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binaryfunc nb_inplace_subtract; |
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binaryfunc nb_inplace_multiply; |
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binaryfunc nb_inplace_divide; |
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binaryfunc nb_inplace_remainder; |
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ternaryfunc nb_inplace_power; |
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binaryfunc nb_inplace_lshift; |
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binaryfunc nb_inplace_rshift; |
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binaryfunc nb_inplace_and; |
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binaryfunc nb_inplace_xor; |
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binaryfunc nb_inplace_or; |
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/* Added in release 2.2 */ |
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/* The following require the Py_TPFLAGS_HAVE_CLASS flag */ |
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binaryfunc nb_floor_divide; |
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binaryfunc nb_true_divide; |
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binaryfunc nb_inplace_floor_divide; |
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binaryfunc nb_inplace_true_divide; |
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} PyNumberMethods; |
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typedef struct { |
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inquiry sq_length; |
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binaryfunc sq_concat; |
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intargfunc sq_repeat; |
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intargfunc sq_item; |
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intintargfunc sq_slice; |
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intobjargproc sq_ass_item; |
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intintobjargproc sq_ass_slice; |
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objobjproc sq_contains; |
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/* Added in release 2.0 */ |
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binaryfunc sq_inplace_concat; |
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intargfunc sq_inplace_repeat; |
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} PySequenceMethods; |
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typedef struct { |
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inquiry mp_length; |
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binaryfunc mp_subscript; |
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objobjargproc mp_ass_subscript; |
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} PyMappingMethods; |
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typedef struct { |
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getreadbufferproc bf_getreadbuffer; |
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getwritebufferproc bf_getwritebuffer; |
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getsegcountproc bf_getsegcount; |
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getcharbufferproc bf_getcharbuffer; |
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} PyBufferProcs; |
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typedef void (*freefunc)(void *); |
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typedef void (*destructor)(PyObject *); |
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typedef int (*printfunc)(PyObject *, FILE *, int); |
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typedef PyObject *(*getattrfunc)(PyObject *, char *); |
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typedef PyObject *(*getattrofunc)(PyObject *, PyObject *); |
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typedef int (*setattrfunc)(PyObject *, char *, PyObject *); |
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typedef int (*setattrofunc)(PyObject *, PyObject *, PyObject *); |
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typedef int (*cmpfunc)(PyObject *, PyObject *); |
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typedef PyObject *(*reprfunc)(PyObject *); |
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typedef long (*hashfunc)(PyObject *); |
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typedef PyObject *(*richcmpfunc) (PyObject *, PyObject *, int); |
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typedef PyObject *(*getiterfunc) (PyObject *); |
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typedef PyObject *(*iternextfunc) (PyObject *); |
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typedef PyObject *(*descrgetfunc) (PyObject *, PyObject *, PyObject *); |
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typedef int (*descrsetfunc) (PyObject *, PyObject *, PyObject *); |
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typedef int (*initproc)(PyObject *, PyObject *, PyObject *); |
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typedef PyObject *(*newfunc)(struct _typeobject *, PyObject *, PyObject *); |
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typedef PyObject *(*allocfunc)(struct _typeobject *, int); |
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typedef struct _typeobject { |
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PyObject_VAR_HEAD |
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char *tp_name; /* For printing, in format "<module>.<name>" */ |
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int tp_basicsize, tp_itemsize; /* For allocation */ |
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/* Methods to implement standard operations */ |
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destructor tp_dealloc; |
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printfunc tp_print; |
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getattrfunc tp_getattr; |
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setattrfunc tp_setattr; |
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cmpfunc tp_compare; |
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reprfunc tp_repr; |
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/* Method suites for standard classes */ |
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PyNumberMethods *tp_as_number; |
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PySequenceMethods *tp_as_sequence; |
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PyMappingMethods *tp_as_mapping; |
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/* More standard operations (here for binary compatibility) */ |
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hashfunc tp_hash; |
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ternaryfunc tp_call; |
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reprfunc tp_str; |
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getattrofunc tp_getattro; |
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setattrofunc tp_setattro; |
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/* Functions to access object as input/output buffer */ |
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PyBufferProcs *tp_as_buffer; |
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/* Flags to define presence of optional/expanded features */ |
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long tp_flags; |
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char *tp_doc; /* Documentation string */ |
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/* Assigned meaning in release 2.0 */ |
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/* call function for all accessible objects */ |
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traverseproc tp_traverse; |
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/* delete references to contained objects */ |
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inquiry tp_clear; |
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/* Assigned meaning in release 2.1 */ |
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/* rich comparisons */ |
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richcmpfunc tp_richcompare; |
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/* weak reference enabler */ |
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long tp_weaklistoffset; |
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/* Added in release 2.2 */ |
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/* Iterators */ |
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getiterfunc tp_iter; |
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iternextfunc tp_iternext; |
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/* Attribute descriptor and subclassing stuff */ |
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struct PyMethodDef *tp_methods; |
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struct PyMemberDef *tp_members; |
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struct PyGetSetDef *tp_getset; |
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struct _typeobject *tp_base; |
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PyObject *tp_dict; |
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descrgetfunc tp_descr_get; |
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descrsetfunc tp_descr_set; |
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long tp_dictoffset; |
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initproc tp_init; |
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allocfunc tp_alloc; |
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newfunc tp_new; |
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freefunc tp_free; /* Low-level free-memory routine */ |
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inquiry tp_is_gc; /* For PyObject_IS_GC */ |
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PyObject *tp_bases; |
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PyObject *tp_mro; /* method resolution order */ |
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PyObject *tp_cache; |
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PyObject *tp_subclasses; |
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PyObject *tp_weaklist; |
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destructor tp_del; |
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#ifdef COUNT_ALLOCS |
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/* these must be last and never explicitly initialized */ |
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int tp_allocs; |
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int tp_frees; |
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int tp_maxalloc; |
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struct _typeobject *tp_next; |
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#endif |
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} PyTypeObject; |
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/* The *real* layout of a type object when allocated on the heap */ |
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typedef struct _heaptypeobject { |
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/* Note: there's a dependency on the order of these members |
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in slotptr() in typeobject.c . */ |
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PyTypeObject type; |
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PyNumberMethods as_number; |
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PyMappingMethods as_mapping; |
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PySequenceMethods as_sequence; /* as_sequence comes after as_mapping, |
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so that the mapping wins when both |
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the mapping and the sequence define |
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a given operator (e.g. __getitem__). |
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see add_operators() in typeobject.c . */ |
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PyBufferProcs as_buffer; |
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PyObject *name, *slots; |
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/* here are optional user slots, followed by the members. */ |
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} PyHeapTypeObject; |
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|
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/* access macro to the members which are floating "behind" the object */ |
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#define PyHeapType_GET_MEMBERS(etype) \ |
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((PyMemberDef *)(((char *)etype) + (etype)->type.ob_type->tp_basicsize)) |
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/* Generic type check */ |
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PyAPI_FUNC(int) PyType_IsSubtype(PyTypeObject *, PyTypeObject *); |
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#define PyObject_TypeCheck(ob, tp) \ |
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((ob)->ob_type == (tp) || PyType_IsSubtype((ob)->ob_type, (tp))) |
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PyAPI_DATA(PyTypeObject) PyType_Type; /* built-in 'type' */ |
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PyAPI_DATA(PyTypeObject) PyBaseObject_Type; /* built-in 'object' */ |
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PyAPI_DATA(PyTypeObject) PySuper_Type; /* built-in 'super' */ |
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#define PyType_Check(op) PyObject_TypeCheck(op, &PyType_Type) |
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#define PyType_CheckExact(op) ((op)->ob_type == &PyType_Type) |
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PyAPI_FUNC(int) PyType_Ready(PyTypeObject *); |
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PyAPI_FUNC(PyObject *) PyType_GenericAlloc(PyTypeObject *, int); |
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PyAPI_FUNC(PyObject *) PyType_GenericNew(PyTypeObject *, |
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PyObject *, PyObject *); |
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PyAPI_FUNC(PyObject *) _PyType_Lookup(PyTypeObject *, PyObject *); |
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/* Generic operations on objects */ |
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PyAPI_FUNC(int) PyObject_Print(PyObject *, FILE *, int); |
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PyAPI_FUNC(void) _PyObject_Dump(PyObject *); |
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PyAPI_FUNC(PyObject *) PyObject_Repr(PyObject *); |
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PyAPI_FUNC(PyObject *) PyObject_Str(PyObject *); |
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#ifdef Py_USING_UNICODE |
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PyAPI_FUNC(PyObject *) PyObject_Unicode(PyObject *); |
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#endif |
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PyAPI_FUNC(int) PyObject_Compare(PyObject *, PyObject *); |
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PyAPI_FUNC(PyObject *) PyObject_RichCompare(PyObject *, PyObject *, int); |
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PyAPI_FUNC(int) PyObject_RichCompareBool(PyObject *, PyObject *, int); |
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PyAPI_FUNC(PyObject *) PyObject_GetAttrString(PyObject *, char *); |
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PyAPI_FUNC(int) PyObject_SetAttrString(PyObject *, char *, PyObject *); |
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PyAPI_FUNC(int) PyObject_HasAttrString(PyObject *, char *); |
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PyAPI_FUNC(PyObject *) PyObject_GetAttr(PyObject *, PyObject *); |
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PyAPI_FUNC(int) PyObject_SetAttr(PyObject *, PyObject *, PyObject *); |
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PyAPI_FUNC(int) PyObject_HasAttr(PyObject *, PyObject *); |
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PyAPI_FUNC(PyObject **) _PyObject_GetDictPtr(PyObject *); |
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PyAPI_FUNC(PyObject *) PyObject_SelfIter(PyObject *); |
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PyAPI_FUNC(PyObject *) PyObject_GenericGetAttr(PyObject *, PyObject *); |
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PyAPI_FUNC(int) PyObject_GenericSetAttr(PyObject *, |
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PyObject *, PyObject *); |
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PyAPI_FUNC(long) PyObject_Hash(PyObject *); |
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PyAPI_FUNC(int) PyObject_IsTrue(PyObject *); |
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PyAPI_FUNC(int) PyObject_Not(PyObject *); |
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PyAPI_FUNC(int) PyCallable_Check(PyObject *); |
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PyAPI_FUNC(int) PyNumber_Coerce(PyObject **, PyObject **); |
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PyAPI_FUNC(int) PyNumber_CoerceEx(PyObject **, PyObject **); |
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PyAPI_FUNC(void) PyObject_ClearWeakRefs(PyObject *); |
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/* A slot function whose address we need to compare */ |
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extern int _PyObject_SlotCompare(PyObject *, PyObject *); |
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/* PyObject_Dir(obj) acts like Python __builtin__.dir(obj), returning a |
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list of strings. PyObject_Dir(NULL) is like __builtin__.dir(), |
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returning the names of the current locals. In this case, if there are |
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no current locals, NULL is returned, and PyErr_Occurred() is false. |
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*/ |
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PyAPI_FUNC(PyObject *) PyObject_Dir(PyObject *); |
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/* Helpers for printing recursive container types */ |
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PyAPI_FUNC(int) Py_ReprEnter(PyObject *); |
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PyAPI_FUNC(void) Py_ReprLeave(PyObject *); |
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/* Helpers for hash functions */ |
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PyAPI_FUNC(long) _Py_HashDouble(double); |
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PyAPI_FUNC(long) _Py_HashPointer(void*); |
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/* Helper for passing objects to printf and the like */ |
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#define PyObject_REPR(obj) PyString_AS_STRING(PyObject_Repr(obj)) |
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/* Flag bits for printing: */ |
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#define Py_PRINT_RAW 1 /* No string quotes etc. */ |
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/* |
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`Type flags (tp_flags) |
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These flags are used to extend the type structure in a backwards-compatible |
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fashion. Extensions can use the flags to indicate (and test) when a given |
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type structure contains a new feature. The Python core will use these when |
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introducing new functionality between major revisions (to avoid mid-version |
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changes in the PYTHON_API_VERSION). |
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|
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Arbitration of the flag bit positions will need to be coordinated among |
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all extension writers who publically release their extensions (this will |
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be fewer than you might expect!).. |
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Python 1.5.2 introduced the bf_getcharbuffer slot into PyBufferProcs. |
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Type definitions should use Py_TPFLAGS_DEFAULT for their tp_flags value. |
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Code can use PyType_HasFeature(type_ob, flag_value) to test whether the |
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given type object has a specified feature. |
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*/ |
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/* PyBufferProcs contains bf_getcharbuffer */ |
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#define Py_TPFLAGS_HAVE_GETCHARBUFFER (1L<<0) |
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|
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/* PySequenceMethods contains sq_contains */ |
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#define Py_TPFLAGS_HAVE_SEQUENCE_IN (1L<<1) |
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/* This is here for backwards compatibility. Extensions that use the old GC |
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* API will still compile but the objects will not be tracked by the GC. */ |
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#define Py_TPFLAGS_GC 0 /* used to be (1L<<2) */ |
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|
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/* PySequenceMethods and PyNumberMethods contain in-place operators */ |
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#define Py_TPFLAGS_HAVE_INPLACEOPS (1L<<3) |
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|
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/* PyNumberMethods do their own coercion */ |
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#define Py_TPFLAGS_CHECKTYPES (1L<<4) |
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|
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/* tp_richcompare is defined */ |
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#define Py_TPFLAGS_HAVE_RICHCOMPARE (1L<<5) |
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|
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/* Objects which are weakly referencable if their tp_weaklistoffset is >0 */ |
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#define Py_TPFLAGS_HAVE_WEAKREFS (1L<<6) |
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/* tp_iter is defined */ |
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#define Py_TPFLAGS_HAVE_ITER (1L<<7) |
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/* New members introduced by Python 2.2 exist */ |
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#define Py_TPFLAGS_HAVE_CLASS (1L<<8) |
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/* Set if the type object is dynamically allocated */ |
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#define Py_TPFLAGS_HEAPTYPE (1L<<9) |
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/* Set if the type allows subclassing */ |
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#define Py_TPFLAGS_BASETYPE (1L<<10) |
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|
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/* Set if the type is 'ready' -- fully initialized */ |
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#define Py_TPFLAGS_READY (1L<<12) |
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|
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/* Set while the type is being 'readied', to prevent recursive ready calls */ |
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#define Py_TPFLAGS_READYING (1L<<13) |
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|
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/* Objects support garbage collection (see objimp.h) */ |
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#define Py_TPFLAGS_HAVE_GC (1L<<14) |
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|
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/* These two bits are preserved for Stackless Python, next after this is 16 */ |
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#ifdef STACKLESS |
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#define Py_TPFLAGS_HAVE_STACKLESS_EXTENSION (3L<<15) |
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#else |
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#define Py_TPFLAGS_HAVE_STACKLESS_EXTENSION 0 |
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#endif |
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#define Py_TPFLAGS_DEFAULT ( \ |
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Py_TPFLAGS_HAVE_GETCHARBUFFER | \ |
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Py_TPFLAGS_HAVE_SEQUENCE_IN | \ |
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Py_TPFLAGS_HAVE_INPLACEOPS | \ |
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Py_TPFLAGS_HAVE_RICHCOMPARE | \ |
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Py_TPFLAGS_HAVE_WEAKREFS | \ |
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Py_TPFLAGS_HAVE_ITER | \ |
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Py_TPFLAGS_HAVE_CLASS | \ |
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Py_TPFLAGS_HAVE_STACKLESS_EXTENSION | \ |
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0) |
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|
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#define PyType_HasFeature(t,f) (((t)->tp_flags & (f)) != 0) |
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|
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/* |
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The macros Py_INCREF(op) and Py_DECREF(op) are used to increment or decrement |
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reference counts. Py_DECREF calls the object's deallocator function when |
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the refcount falls to 0; for |
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objects that don't contain references to other objects or heap memory |
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this can be the standard function free(). Both macros can be used |
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wherever a void expression is allowed. The argument must not be a |
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NIL pointer. If it may be NIL, use Py_XINCREF/Py_XDECREF instead. |
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The macro _Py_NewReference(op) initialize reference counts to 1, and |
|
in special builds (Py_REF_DEBUG, Py_TRACE_REFS) performs additional |
|
bookkeeping appropriate to the special build. |
|
|
|
We assume that the reference count field can never overflow; this can |
|
be proven when the size of the field is the same as the pointer size, so |
|
we ignore the possibility. Provided a C int is at least 32 bits (which |
|
is implicitly assumed in many parts of this code), that's enough for |
|
about 2**31 references to an object. |
|
|
|
XXX The following became out of date in Python 2.2, but I'm not sure |
|
XXX what the full truth is now. Certainly, heap-allocated type objects |
|
XXX can and should be deallocated. |
|
Type objects should never be deallocated; the type pointer in an object |
|
is not considered to be a reference to the type object, to save |
|
complications in the deallocation function. (This is actually a |
|
decision that's up to the implementer of each new type so if you want, |
|
you can count such references to the type object.) |
|
|
|
*** WARNING*** The Py_DECREF macro must have a side-effect-free argument |
|
since it may evaluate its argument multiple times. (The alternative |
|
would be to mace it a proper function or assign it to a global temporary |
|
variable first, both of which are slower; and in a multi-threaded |
|
environment the global variable trick is not safe.) |
|
*/ |
|
|
|
/* First define a pile of simple helper macros, one set per special |
|
* build symbol. These either expand to the obvious things, or to |
|
* nothing at all when the special mode isn't in effect. The main |
|
* macros can later be defined just once then, yet expand to different |
|
* things depending on which special build options are and aren't in effect. |
|
* Trust me <wink>: while painful, this is 20x easier to understand than, |
|
* e.g, defining _Py_NewReference five different times in a maze of nested |
|
* #ifdefs (we used to do that -- it was impenetrable). |
|
*/ |
|
#ifdef Py_REF_DEBUG |
|
PyAPI_DATA(long) _Py_RefTotal; |
|
PyAPI_FUNC(void) _Py_NegativeRefcount(const char *fname, |
|
int lineno, PyObject *op); |
|
#define _Py_INC_REFTOTAL _Py_RefTotal++ |
|
#define _Py_DEC_REFTOTAL _Py_RefTotal-- |
|
#define _Py_REF_DEBUG_COMMA , |
|
#define _Py_CHECK_REFCNT(OP) \ |
|
{ if ((OP)->ob_refcnt < 0) \ |
|
_Py_NegativeRefcount(__FILE__, __LINE__, \ |
|
(PyObject *)(OP)); \ |
|
} |
|
#else |
|
#define _Py_INC_REFTOTAL |
|
#define _Py_DEC_REFTOTAL |
|
#define _Py_REF_DEBUG_COMMA |
|
#define _Py_CHECK_REFCNT(OP) /* a semicolon */; |
|
#endif /* Py_REF_DEBUG */ |
|
|
|
#ifdef COUNT_ALLOCS |
|
PyAPI_FUNC(void) inc_count(PyTypeObject *); |
|
#define _Py_INC_TPALLOCS(OP) inc_count((OP)->ob_type) |
|
#define _Py_INC_TPFREES(OP) (OP)->ob_type->tp_frees++ |
|
#define _Py_DEC_TPFREES(OP) (OP)->ob_type->tp_frees-- |
|
#define _Py_COUNT_ALLOCS_COMMA , |
|
#else |
|
#define _Py_INC_TPALLOCS(OP) |
|
#define _Py_INC_TPFREES(OP) |
|
#define _Py_DEC_TPFREES(OP) |
|
#define _Py_COUNT_ALLOCS_COMMA |
|
#endif /* COUNT_ALLOCS */ |
|
|
|
#ifdef Py_TRACE_REFS |
|
/* Py_TRACE_REFS is such major surgery that we call external routines. */ |
|
PyAPI_FUNC(void) _Py_NewReference(PyObject *); |
|
PyAPI_FUNC(void) _Py_ForgetReference(PyObject *); |
|
PyAPI_FUNC(void) _Py_Dealloc(PyObject *); |
|
PyAPI_FUNC(void) _Py_PrintReferences(FILE *); |
|
PyAPI_FUNC(void) _Py_PrintReferenceAddresses(FILE *); |
|
PyAPI_FUNC(void) _Py_AddToAllObjects(PyObject *, int force); |
|
|
|
#else |
|
/* Without Py_TRACE_REFS, there's little enough to do that we expand code |
|
* inline. |
|
*/ |
|
#define _Py_NewReference(op) ( \ |
|
_Py_INC_TPALLOCS(op) _Py_COUNT_ALLOCS_COMMA \ |
|
_Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA \ |
|
(op)->ob_refcnt = 1) |
|
|
|
#define _Py_ForgetReference(op) _Py_INC_TPFREES(op) |
|
|
|
#define _Py_Dealloc(op) ( \ |
|
_Py_INC_TPFREES(op) _Py_COUNT_ALLOCS_COMMA \ |
|
(*(op)->ob_type->tp_dealloc)((PyObject *)(op))) |
|
#endif /* !Py_TRACE_REFS */ |
|
|
|
#define Py_INCREF(op) ( \ |
|
_Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA \ |
|
(op)->ob_refcnt++) |
|
|
|
#define Py_DECREF(op) \ |
|
if (_Py_DEC_REFTOTAL _Py_REF_DEBUG_COMMA \ |
|
--(op)->ob_refcnt != 0) \ |
|
_Py_CHECK_REFCNT(op) \ |
|
else \ |
|
_Py_Dealloc((PyObject *)(op)) |
|
|
|
/* Macros to use in case the object pointer may be NULL: */ |
|
#define Py_XINCREF(op) if ((op) == NULL) ; else Py_INCREF(op) |
|
#define Py_XDECREF(op) if ((op) == NULL) ; else Py_DECREF(op) |
|
|
|
/* |
|
_Py_NoneStruct is an object of undefined type which can be used in contexts |
|
where NULL (nil) is not suitable (since NULL often means 'error'). |
|
|
|
Don't forget to apply Py_INCREF() when returning this value!!! |
|
*/ |
|
PyAPI_DATA(PyObject) _Py_NoneStruct; /* Don't use this directly */ |
|
#define Py_None (&_Py_NoneStruct) |
|
|
|
/* |
|
Py_NotImplemented is a singleton used to signal that an operation is |
|
not implemented for a given type combination. |
|
*/ |
|
PyAPI_DATA(PyObject) _Py_NotImplementedStruct; /* Don't use this directly */ |
|
#define Py_NotImplemented (&_Py_NotImplementedStruct) |
|
|
|
/* Rich comparison opcodes */ |
|
#define Py_LT 0 |
|
#define Py_LE 1 |
|
#define Py_EQ 2 |
|
#define Py_NE 3 |
|
#define Py_GT 4 |
|
#define Py_GE 5 |
|
|
|
/* |
|
Define staticforward and statichere for source compatibility with old |
|
C extensions. |
|
|
|
The staticforward define was needed to support certain broken C |
|
compilers (notably SCO ODT 3.0, perhaps early AIX as well) botched the |
|
static keyword when it was used with a forward declaration of a static |
|
initialized structure. Standard C allows the forward declaration with |
|
static, and we've decided to stop catering to broken C compilers. |
|
(In fact, we expect that the compilers are all fixed eight years later.) |
|
*/ |
|
|
|
#define staticforward static |
|
#define statichere static |
|
|
|
|
|
/* |
|
More conventions |
|
================ |
|
|
|
Argument Checking |
|
----------------- |
|
|
|
Functions that take objects as arguments normally don't check for nil |
|
arguments, but they do check the type of the argument, and return an |
|
error if the function doesn't apply to the type. |
|
|
|
Failure Modes |
|
------------- |
|
|
|
Functions may fail for a variety of reasons, including running out of |
|
memory. This is communicated to the caller in two ways: an error string |
|
is set (see errors.h), and the function result differs: functions that |
|
normally return a pointer return NULL for failure, functions returning |
|
an integer return -1 (which could be a legal return value too!), and |
|
other functions return 0 for success and -1 for failure. |
|
Callers should always check for errors before using the result. If |
|
an error was set, the caller must either explicitly clear it, or pass |
|
the error on to its caller. |
|
|
|
Reference Counts |
|
---------------- |
|
|
|
It takes a while to get used to the proper usage of reference counts. |
|
|
|
Functions that create an object set the reference count to 1; such new |
|
objects must be stored somewhere or destroyed again with Py_DECREF(). |
|
Some functions that 'store' objects, such as PyTuple_SetItem() and |
|
PyList_SetItem(), |
|
don't increment the reference count of the object, since the most |
|
frequent use is to store a fresh object. Functions that 'retrieve' |
|
objects, such as PyTuple_GetItem() and PyDict_GetItemString(), also |
|
don't increment |
|
the reference count, since most frequently the object is only looked at |
|
quickly. Thus, to retrieve an object and store it again, the caller |
|
must call Py_INCREF() explicitly. |
|
|
|
NOTE: functions that 'consume' a reference count, like |
|
PyList_SetItem(), consume the reference even if the object wasn't |
|
successfully stored, to simplify error handling. |
|
|
|
It seems attractive to make other functions that take an object as |
|
argument consume a reference count; however, this may quickly get |
|
confusing (even the current practice is already confusing). Consider |
|
it carefully, it may save lots of calls to Py_INCREF() and Py_DECREF() at |
|
times. |
|
*/ |
|
|
|
|
|
/* Trashcan mechanism, thanks to Christian Tismer. |
|
|
|
When deallocating a container object, it's possible to trigger an unbounded |
|
chain of deallocations, as each Py_DECREF in turn drops the refcount on "the |
|
next" object in the chain to 0. This can easily lead to stack faults, and |
|
especially in threads (which typically have less stack space to work with). |
|
|
|
A container object that participates in cyclic gc can avoid this by |
|
bracketing the body of its tp_dealloc function with a pair of macros: |
|
|
|
static void |
|
mytype_dealloc(mytype *p) |
|
{ |
|
... declarations go here ... |
|
|
|
PyObject_GC_UnTrack(p); // must untrack first |
|
Py_TRASHCAN_SAFE_BEGIN(p) |
|
... The body of the deallocator goes here, including all calls ... |
|
... to Py_DECREF on contained objects. ... |
|
Py_TRASHCAN_SAFE_END(p) |
|
} |
|
|
|
CAUTION: Never return from the middle of the body! If the body needs to |
|
"get out early", put a label immediately before the Py_TRASHCAN_SAFE_END |
|
call, and goto it. Else the call-depth counter (see below) will stay |
|
above 0 forever, and the trashcan will never get emptied. |
|
|
|
How it works: The BEGIN macro increments a call-depth counter. So long |
|
as this counter is small, the body of the deallocator is run directly without |
|
further ado. But if the counter gets large, it instead adds p to a list of |
|
objects to be deallocated later, skips the body of the deallocator, and |
|
resumes execution after the END macro. The tp_dealloc routine then returns |
|
without deallocating anything (and so unbounded call-stack depth is avoided). |
|
|
|
When the call stack finishes unwinding again, code generated by the END macro |
|
notices this, and calls another routine to deallocate all the objects that |
|
may have been added to the list of deferred deallocations. In effect, a |
|
chain of N deallocations is broken into N / PyTrash_UNWIND_LEVEL pieces, |
|
with the call stack never exceeding a depth of PyTrash_UNWIND_LEVEL. |
|
*/ |
|
|
|
PyAPI_FUNC(void) _PyTrash_deposit_object(PyObject*); |
|
PyAPI_FUNC(void) _PyTrash_destroy_chain(void); |
|
PyAPI_DATA(int) _PyTrash_delete_nesting; |
|
PyAPI_DATA(PyObject *) _PyTrash_delete_later; |
|
|
|
#define PyTrash_UNWIND_LEVEL 50 |
|
|
|
#define Py_TRASHCAN_SAFE_BEGIN(op) \ |
|
if (_PyTrash_delete_nesting < PyTrash_UNWIND_LEVEL) { \ |
|
++_PyTrash_delete_nesting; |
|
/* The body of the deallocator is here. */ |
|
#define Py_TRASHCAN_SAFE_END(op) \ |
|
--_PyTrash_delete_nesting; \ |
|
if (_PyTrash_delete_later && _PyTrash_delete_nesting <= 0) \ |
|
_PyTrash_destroy_chain(); \ |
|
} \ |
|
else \ |
|
_PyTrash_deposit_object((PyObject*)op); |
|
|
|
#ifdef __cplusplus |
|
} |
|
#endif |
|
#endif /* !Py_OBJECT_H */
|
|
|