Modules/_weakref.c

   1 #include "Python.h"
   2
   3
   4 #define GET_WEAKREFS_LISTPTR(o) \
   5         ((PyWeakReference **) PyObject_GET_WEAKREFS_LISTPTR(o))
   6
   7
   8 PyDoc_STRVAR(weakref_getweakrefcount__doc__,
   9 "getweakrefcount(object) -- return the number of weak references\n"
  10 "to 'object'.");
  11
  12 static PyObject *
  13 weakref_getweakrefcount(PyObject *self, PyObject *object)
  14 {
  15     PyObject *result = NULL;
  16
  17     if (PyType_SUPPORTS_WEAKREFS(object->ob_type)) {
  18         PyWeakReference **list = GET_WEAKREFS_LISTPTR(object);
  19
  20         result = PyInt_FromLong(_PyWeakref_GetWeakrefCount(*list));
  21     }
  22     else
  23         result = PyInt_FromLong(0);
  24
  25     return result;
  26 }
  27
  28
  29 PyDoc_STRVAR(weakref_getweakrefs__doc__,
  30 "getweakrefs(object) -- return a list of all weak reference objects\n"
  31 "that point to 'object'.");
  32
  33 static PyObject *
  34 weakref_getweakrefs(PyObject *self, PyObject *object)
  35 {
  36     PyObject *result = NULL;
  37
  38     if (PyType_SUPPORTS_WEAKREFS(object->ob_type)) {
  39         PyWeakReference **list = GET_WEAKREFS_LISTPTR(object);
  40         long count = _PyWeakref_GetWeakrefCount(*list);
  41
  42         result = PyList_New(count);
  43         if (result != NULL) {
  44             PyWeakReference *current = *list;
  45             long i;
  46             for (i = 0; i < count; ++i) {
  47                 PyList_SET_ITEM(result, i, (PyObject *) current);
  48                 Py_INCREF(current);
  49                 current = current->wr_next;
  50             }
  51         }
  52     }
  53     else {
  54         result = PyList_New(0);
  55     }
  56     return result;
  57 }
  58
  59
  60 PyDoc_STRVAR(weakref_ref__doc__,
  61 "ref(object[, callback]) -- create a weak reference to 'object';\n"
  62 "when 'object' is finalized, 'callback' will be called and passed\n"
  63 "a reference to the weak reference object when 'object' is about\n"
  64 "to be finalized.");
  65
  66 static PyObject *
  67 weakref_ref(PyObject *self, PyObject *args)
  68 {
  69     PyObject *object;
  70     PyObject *callback = NULL;
  71     PyObject *result = NULL;
  72
  73     if (PyArg_UnpackTuple(args, "ref", 1, 2, &object, &callback)) {
  74         result = PyWeakref_NewRef(object, callback);
  75     }
  76     return result;
  77 }
  78
  79
  80 PyDoc_STRVAR(weakref_proxy__doc__,
  81 "proxy(object[, callback]) -- create a proxy object that weakly\n"
  82 "references 'object'.  'callback', if given, is called with a\n"
  83 "reference to the proxy when 'object' is about to be finalized.");
  84
  85 static PyObject *
  86 weakref_proxy(PyObject *self, PyObject *args)
  87 {
  88     PyObject *object;
  89     PyObject *callback = NULL;
  90     PyObject *result = NULL;
  91
  92     if (PyArg_UnpackTuple(args, "proxy", 1, 2, &object, &callback)) {
  93         result = PyWeakref_NewProxy(object, callback);
  94     }
  95     return result;
  96 }
  97
  98
  99 static PyMethodDef
 100 weakref_functions[] =  {
 101     {"getweakrefcount", weakref_getweakrefcount,        METH_O,
 102      weakref_getweakrefcount__doc__},
 103     {"getweakrefs",     weakref_getweakrefs,            METH_O,
 104      weakref_getweakrefs__doc__},
 105     {"proxy",           weakref_proxy,                  METH_VARARGS,
 106      weakref_proxy__doc__},
 107     {"ref",             weakref_ref,                    METH_VARARGS,
 108      weakref_ref__doc__},
 109     {NULL, NULL, 0, NULL}
 110 };
 111
 112
 113 PyMODINIT_FUNC
 114 init_weakref(void)
 115 {
 116     PyObject *m;
 117
 118     m = Py_InitModule3("_weakref", weakref_functions,
 119                        "Weak-reference support module.");
 120     if (m != NULL) {
 121         Py_INCREF(&_PyWeakref_RefType);
 122         PyModule_AddObject(m, "ReferenceType",
 123                            (PyObject *) &_PyWeakref_RefType);
 124         Py_INCREF(&_PyWeakref_ProxyType);
 125         PyModule_AddObject(m, "ProxyType",
 126                            (PyObject *) &_PyWeakref_ProxyType);
 127         Py_INCREF(&_PyWeakref_CallableProxyType);
 128         PyModule_AddObject(m, "CallableProxyType",
 129                            (PyObject *) &_PyWeakref_CallableProxyType);
 130     }
 131 }