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v0.5.1
https://github.com/python/cpython
09 December 2020, 11:06:31 UTC
Revision 972aba86ede0bf254e16a760639a1ff8df298578 authored by Antoine Pitrou on 10 June 2020, 20:38:42 UTC, committed by GitHub on 10 June 2020, 20:38:42 UTC 
[3.8] bpo-40895: Update weakref documentation to remove old warnings (GH-20687) (GH-20792)
 


The doccumentation at https://docs.python.org/3.10/library/weakref.html cautions that the `WeakKeyDictionary` and `WeakValueDictionary` are susceptible to the problem of dictionary mutation during iteration.

These notes present the user with a problem that has no easy solution.

I dug into the implementation and found that fortunately, Antoine Pitrou already addressed this challenge (10 years ago!) by introducing an `_IterationGuard` context manager to the implementation, which delays mutation while an iteration is in progress.

I asked for confirmation and @pitrou agreed that these notes could be removed:
https://github.com/python/cpython/commit/c1baa601e2b558deb690edfdf334fceee3b03327GH-commitcomment-39514438.
(cherry picked from commit 1642c0ef750f96664a98cadb09301d492098d2fb)

Co-authored-by: Daniel Fortunov <asqui@users.noreply.github.com>

Automerge-Triggered-By: @pitrou
1 parent c7a6c7b
Raw File
Tip revision: 972aba86ede0bf254e16a760639a1ff8df298578 authored by Antoine Pitrou on 10 June 2020, 20:38:42 UTC
[3.8] bpo-40895: Update weakref documentation to remove old warnings (GH-20687) (GH-20792)
Tip revision: 972aba8
odictobject.h 
#ifndef Py_ODICTOBJECT_H
#define Py_ODICTOBJECT_H
#ifdef __cplusplus
extern "C" {
#endif


/* OrderedDict */
/* This API is optional and mostly redundant. */

#ifndef Py_LIMITED_API

typedef struct _odictobject PyODictObject;

PyAPI_DATA(PyTypeObject) PyODict_Type;
PyAPI_DATA(PyTypeObject) PyODictIter_Type;
PyAPI_DATA(PyTypeObject) PyODictKeys_Type;
PyAPI_DATA(PyTypeObject) PyODictItems_Type;
PyAPI_DATA(PyTypeObject) PyODictValues_Type;

#define PyODict_Check(op) PyObject_TypeCheck(op, &PyODict_Type)
#define PyODict_CheckExact(op) (Py_TYPE(op) == &PyODict_Type)
#define PyODict_SIZE(op) PyDict_GET_SIZE((op))

PyAPI_FUNC(PyObject *) PyODict_New(void);
PyAPI_FUNC(int) PyODict_SetItem(PyObject *od, PyObject *key, PyObject *item);
PyAPI_FUNC(int) PyODict_DelItem(PyObject *od, PyObject *key);

/* wrappers around PyDict* functions */
#define PyODict_GetItem(od, key) PyDict_GetItem(_PyObject_CAST(od), key)
#define PyODict_GetItemWithError(od, key) \
    PyDict_GetItemWithError(_PyObject_CAST(od), key)
#define PyODict_Contains(od, key) PyDict_Contains(_PyObject_CAST(od), key)
#define PyODict_Size(od) PyDict_Size(_PyObject_CAST(od))
#define PyODict_GetItemString(od, key) \
    PyDict_GetItemString(_PyObject_CAST(od), key)

#endif

#ifdef __cplusplus
}
#endif
#endif /* !Py_ODICTOBJECT_H */
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