Dictionary Objects — Python 3.13.1 documentation

int PyDict_Pop ( PyObject * p , PyObject * key , PyObject * * result ) ¶

移除 key from dictionary p and optionally return the removed value. Do not raise KeyError if the key missing.

If the key is present, set *result to a new reference to the removed value if result 不是 NULL , and return 1 .
If the key is missing, set *result to NULL if result 不是 NULL , and return 0 .
On error, raise an exception and return -1 .

这类似于 dict.pop() , but without the default value and not raising KeyError if the key missing.

3.13 版添加。

int PyDict_PopString ( PyObject * p , const char * key , PyObject * * result ) ¶

类似于 PyDict_Pop() ，但 key is specified as a const char * UTF-8 encoded bytes string, rather than a PyObject * .

3.13 版添加。

PyObject * PyDict_Items ( PyObject * p ) ¶

返回值：新引用。 属于稳定 ABI (应用程序二进制接口) .

返回 PyListObject containing all the items from the dictionary.

PyObject * PyDict_Keys ( PyObject * p ) ¶

返回值：新引用。 属于稳定 ABI (应用程序二进制接口) .

返回 PyListObject containing all the keys from the dictionary.

PyObject * PyDict_Values ( PyObject * p ) ¶

返回值：新引用。 属于稳定 ABI (应用程序二进制接口) .

返回 PyListObject containing all the values from the dictionary p .

Py_ssize_t PyDict_Size ( PyObject * p ) ¶

属于稳定 ABI (应用程序二进制接口) .

Return the number of items in the dictionary. This is equivalent to len(p) on a dictionary.

int PyDict_Next ( PyObject * p , Py_ssize_t * ppos , PyObject * * pkey , PyObject * * pvalue ) ¶

属于稳定 ABI (应用程序二进制接口) .

Iterate over all key-value pairs in the dictionary p 。 Py_ssize_t referred to by ppos must be initialized to 0 prior to the first call to this function to start the iteration; the function returns true for each pair in the dictionary, and false once all pairs have been reported. The parameters pkey and pvalue should either point to PyObject * variables that will be filled in with each key and value, respectively, or may be NULL . Any references returned through them are borrowed. ppos should not be altered during iteration. Its value represents offsets within the internal dictionary structure, and since the structure is sparse, the offsets are not consecutive.

例如：

PyObject *key, *value;
Py_ssize_t pos = 0;
while (PyDict_Next(self->dict, &pos, &key, &value)) {
    /* do something interesting with the values... */
    ...
}

The dictionary p should not be mutated during iteration. It is safe to modify the values of the keys as you iterate over the dictionary, but only so long as the set of keys does not change. For example:

PyObject *key, *value;
Py_ssize_t pos = 0;
while (PyDict_Next(self->dict, &pos, &key, &value)) {
    long i = PyLong_AsLong(value);
    if (i == -1 && PyErr_Occurred()) {
        return -1;
    }
    PyObject *o = PyLong_FromLong(i + 1);
    if (o == NULL)
        return -1;
    if (PyDict_SetItem(self->dict, key, o) < 0) {
        Py_DECREF(o);
        return -1;
    }
    Py_DECREF(o);
}

The function is not thread-safe in the free-threaded build without external synchronization. You can use Py_BEGIN_CRITICAL_SECTION to lock the dictionary while iterating over it:

Py_BEGIN_CRITICAL_SECTION(self->dict);
while (PyDict_Next(self->dict, &pos, &key, &value)) {
    ...
}
Py_END_CRITICAL_SECTION();

int PyDict_Merge ( PyObject * a , PyObject * b , int override ) ¶

属于稳定 ABI (应用程序二进制接口) .

Iterate over mapping object b adding key-value pairs to dictionary a . b may be a dictionary, or any object supporting PyMapping_Keys() and PyObject_GetItem() 。若 override is true, existing pairs in a will be replaced if a matching key is found in b , otherwise pairs will only be added if there is not a matching key in a 。返回 0 当成功时或 -1 if an exception was raised.

int PyDict_Update ( PyObject * a , PyObject * b ) ¶

属于稳定 ABI (应用程序二进制接口) .

这如同 PyDict_Merge(a, b, 1) in C, and is similar to a.update(b) in Python except that PyDict_Update() doesn’t fall back to the iterating over a sequence of key value pairs if the second argument has no “keys” attribute. Return 0 当成功时或 -1 if an exception was raised.

int PyDict_MergeFromSeq2 ( PyObject * a , PyObject * seq2 , int override ) ¶

属于稳定 ABI (应用程序二进制接口) .

Update or merge into dictionary a , from the key-value pairs in seq2 . seq2 must be an iterable object producing iterable objects of length 2, viewed as key-value pairs. In case of duplicate keys, the last wins if override is true, else the first wins. Return 0 当成功时或 -1 if an exception was raised. Equivalent Python (except for the return value):

def PyDict_MergeFromSeq2(a, seq2, override):
    for key, value in seq2:
        if override or key not in a:
            a[key] = value

int PyDict_AddWatcher ( PyDict_WatchCallback callback ) ¶

注册 callback as a dictionary watcher. Return a non-negative integer id which must be passed to future calls to PyDict_Watch() . In case of error (e.g. no more watcher IDs available), return -1 and set an exception.

3.12 版添加。

int PyDict_ClearWatcher ( int watcher_id ) ¶

Clear watcher identified by watcher_id previously returned from PyDict_AddWatcher() 。返回 0 当成功时， -1 on error (e.g. if the given watcher_id was never registered.)

3.12 版添加。

int PyDict_Watch ( int watcher_id , PyObject * dict ) ¶

Mark dictionary dict as watched. The callback granted watcher_id by PyDict_AddWatcher() will be called when dict is modified or deallocated. Return 0 当成功时或 -1 当出错时。

3.12 版添加。

int PyDict_Unwatch ( int watcher_id , PyObject * dict ) ¶

Mark dictionary dict as no longer watched. The callback granted watcher_id by PyDict_AddWatcher() will no longer be called when dict is modified or deallocated. The dict must previously have been watched by this watcher. Return 0 当成功时或 -1 当出错时。

3.12 版添加。

type PyDict_WatchEvent ¶

Enumeration of possible dictionary watcher events: PyDict_EVENT_ADDED , PyDict_EVENT_MODIFIED , PyDict_EVENT_DELETED , PyDict_EVENT_CLONED , PyDict_EVENT_CLEARED ，或 PyDict_EVENT_DEALLOCATED .

3.12 版添加。

typedef int ( * PyDict_WatchCallback ) ( PyDict_WatchEvent event , PyObject * dict , PyObject * key , PyObject * new_value ) ¶

Type of a dict watcher callback function.

若 event is PyDict_EVENT_CLEARED or PyDict_EVENT_DEALLOCATED , both key and new_value 将是 NULL 。若 event is PyDict_EVENT_ADDED or PyDict_EVENT_MODIFIED , new_value will be the new value for key 。若 event is PyDict_EVENT_DELETED , key is being deleted from the dictionary and new_value 将是 NULL .

PyDict_EVENT_CLONED occurs when dict was previously empty and another dict is merged into it. To maintain efficiency of this operation, per-key PyDict_EVENT_ADDED events are not issued in this case; instead a single PyDict_EVENT_CLONED is issued, and key will be the source dictionary.

The callback may inspect but must not modify dict ; doing so could have unpredictable effects, including infinite recursion. Do not trigger Python code execution in the callback, as it could modify the dict as a side effect.

若 event is PyDict_EVENT_DEALLOCATED , taking a new reference in the callback to the about-to-be-destroyed dictionary will resurrect it and prevent it from being freed at this time. When the resurrected object is destroyed later, any watcher callbacks active at that time will be called again.

Callbacks occur before the notified modification to dict takes place, so the prior state of dict can be inspected.

If the callback sets an exception, it must return -1 ; this exception will be printed as an unraisable exception using PyErr_WriteUnraisable() . Otherwise it should return 0 .

There may already be a pending exception set on entry to the callback. In this case, the callback should return 0 with the same exception still set. This means the callback may not call any other API that can set an exception unless it saves and clears the exception state first, and restores it before returning.

3.12 版添加。

字典对象 ¶

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