cpython/Modules/_weakref.c
Fred Drake 0a4dd390bf Make weak references subclassable:
- weakref.ref and weakref.ReferenceType will become aliases for each
  other

- weakref.ref will be a modern, new-style class with proper __new__
  and __init__ methods

- weakref.WeakValueDictionary will have a lighter memory footprint,
  using a new weakref.ref subclass to associate the key with the
  value, allowing us to have only a single object of overhead for each
  dictionary entry (currently, there are 3 objects of overhead per
  entry: a weakref to the value, a weakref to the dictionary, and a
  function object used as a weakref callback; the weakref to the
  dictionary could be avoided without this change)

- a new macro, PyWeakref_CheckRefExact(), will be added

- PyWeakref_CheckRef() will check for subclasses of weakref.ref

This closes SF patch #983019.
2004-07-02 18:57:45 +00:00

113 lines
3.1 KiB
C

#include "Python.h"
#define GET_WEAKREFS_LISTPTR(o) \
((PyWeakReference **) PyObject_GET_WEAKREFS_LISTPTR(o))
PyDoc_STRVAR(weakref_getweakrefcount__doc__,
"getweakrefcount(object) -- return the number of weak references\n"
"to 'object'.");
static PyObject *
weakref_getweakrefcount(PyObject *self, PyObject *object)
{
PyObject *result = NULL;
if (PyType_SUPPORTS_WEAKREFS(object->ob_type)) {
PyWeakReference **list = GET_WEAKREFS_LISTPTR(object);
result = PyInt_FromLong(_PyWeakref_GetWeakrefCount(*list));
}
else
result = PyInt_FromLong(0);
return result;
}
PyDoc_STRVAR(weakref_getweakrefs__doc__,
"getweakrefs(object) -- return a list of all weak reference objects\n"
"that point to 'object'.");
static PyObject *
weakref_getweakrefs(PyObject *self, PyObject *object)
{
PyObject *result = NULL;
if (PyType_SUPPORTS_WEAKREFS(object->ob_type)) {
PyWeakReference **list = GET_WEAKREFS_LISTPTR(object);
long count = _PyWeakref_GetWeakrefCount(*list);
result = PyList_New(count);
if (result != NULL) {
PyWeakReference *current = *list;
long i;
for (i = 0; i < count; ++i) {
PyList_SET_ITEM(result, i, (PyObject *) current);
Py_INCREF(current);
current = current->wr_next;
}
}
}
else {
result = PyList_New(0);
}
return result;
}
PyDoc_STRVAR(weakref_proxy__doc__,
"proxy(object[, callback]) -- create a proxy object that weakly\n"
"references 'object'. 'callback', if given, is called with a\n"
"reference to the proxy when 'object' is about to be finalized.");
static PyObject *
weakref_proxy(PyObject *self, PyObject *args)
{
PyObject *object;
PyObject *callback = NULL;
PyObject *result = NULL;
if (PyArg_UnpackTuple(args, "proxy", 1, 2, &object, &callback)) {
result = PyWeakref_NewProxy(object, callback);
}
return result;
}
static PyMethodDef
weakref_functions[] = {
{"getweakrefcount", weakref_getweakrefcount, METH_O,
weakref_getweakrefcount__doc__},
{"getweakrefs", weakref_getweakrefs, METH_O,
weakref_getweakrefs__doc__},
{"proxy", weakref_proxy, METH_VARARGS,
weakref_proxy__doc__},
{NULL, NULL, 0, NULL}
};
PyMODINIT_FUNC
init_weakref(void)
{
PyObject *m;
m = Py_InitModule3("_weakref", weakref_functions,
"Weak-reference support module.");
if (m != NULL) {
Py_INCREF(&_PyWeakref_RefType);
PyModule_AddObject(m, "ref",
(PyObject *) &_PyWeakref_RefType);
Py_INCREF(&_PyWeakref_RefType);
PyModule_AddObject(m, "ReferenceType",
(PyObject *) &_PyWeakref_RefType);
Py_INCREF(&_PyWeakref_ProxyType);
PyModule_AddObject(m, "ProxyType",
(PyObject *) &_PyWeakref_ProxyType);
Py_INCREF(&_PyWeakref_CallableProxyType);
PyModule_AddObject(m, "CallableProxyType",
(PyObject *) &_PyWeakref_CallableProxyType);
}
}