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The C and C++ Include Header Files

cat -n /usr/include/python3.14/cpython/weakrefobject.h

     1	#ifndef Py_CPYTHON_WEAKREFOBJECT_H
     2	#  error "this header file must not be included directly"
     3	#endif
     4	
     5	/* PyWeakReference is the base struct for the Python ReferenceType, ProxyType,
     6	 * and CallableProxyType.
     7	 */
     8	struct _PyWeakReference {
     9	    PyObject_HEAD
    10	
    11	    /* The object to which this is a weak reference, or Py_None if none.
    12	     * Note that this is a stealth reference:  wr_object's refcount is
    13	     * not incremented to reflect this pointer.
    14	     */
    15	    PyObject *wr_object;
    16	
    17	    /* A callable to invoke when wr_object dies, or NULL if none. */
    18	    PyObject *wr_callback;
    19	
    20	    /* A cache for wr_object's hash code.  As usual for hashes, this is -1
    21	     * if the hash code isn't known yet.
    22	     */
    23	    Py_hash_t hash;
    24	
    25	    /* If wr_object is weakly referenced, wr_object has a doubly-linked NULL-
    26	     * terminated list of weak references to it.  These are the list pointers.
    27	     * If wr_object goes away, wr_object is set to Py_None, and these pointers
    28	     * have no meaning then.
    29	     */
    30	    PyWeakReference *wr_prev;
    31	    PyWeakReference *wr_next;
    32	    vectorcallfunc vectorcall;
    33	
    34	#ifdef Py_GIL_DISABLED
    35	    /* Pointer to the lock used when clearing in free-threaded builds.
    36	     * Normally this can be derived from wr_object, but in some cases we need
    37	     * to lock after wr_object has been set to Py_None.
    38	     */
    39	    PyMutex *weakrefs_lock;
    40	#endif
    41	};
    42	
    43	PyAPI_FUNC(void) _PyWeakref_ClearRef(PyWeakReference *self);
    44	
    45	#define _PyWeakref_CAST(op) \
    46	    (assert(PyWeakref_Check(op)), _Py_CAST(PyWeakReference*, (op)))
    47	
    48	// Test if a weak reference is dead.
    49	PyAPI_FUNC(int) PyWeakref_IsDead(PyObject *ref);
    50	
    51	Py_DEPRECATED(3.13) static inline PyObject* PyWeakref_GET_OBJECT(PyObject *ref_obj)
    52	{
    53	    PyWeakReference *ref = _PyWeakref_CAST(ref_obj);
    54	    PyObject *obj = ref->wr_object;
    55	    // Explanation for the Py_REFCNT() check: when a weakref's target is part
    56	    // of a long chain of deallocations which triggers the trashcan mechanism,
    57	    // clearing the weakrefs can be delayed long after the target's refcount
    58	    // has dropped to zero.  In the meantime, code accessing the weakref will
    59	    // be able to "see" the target object even though it is supposed to be
    60	    // unreachable.  See issue gh-60806.
    61	    if (Py_REFCNT(obj) > 0) {
    62	        return obj;
    63	    }
    64	    return Py_None;
    65	}
    66	#define PyWeakref_GET_OBJECT(ref) PyWeakref_GET_OBJECT(_PyObject_CAST(ref))