Objects/dictobject.c (part 10)

Source:

cpython 3.14 @ ab2d84fe1023/Objects/dictobject.c ↗

This annotation covers dict access and view methods. See objects_dictobject9_detail for dict.update, setdefault, __or__, and _PyDict_MergeEx.

Map

Lines	Symbol	Role
1-80	dict.pop	Remove and return a key's value
81-160	dict.popitem	Remove and return an arbitrary (key, value) pair
161-240	dict.get	Return value or default without raising
241-360	dict.keys / dict.values / dict.items	Return view objects
361-500	dict_view iteration	Iterate over keys/values/items

Reading

dict.pop

// CPython: Objects/dictobject.c:3380 dict_pop_impl
static PyObject *
dict_pop_impl(PyDictObject *self, PyObject *key, PyObject *default_value)
{
    PyObject *old_value;
    Py_hash_t hash = PyObject_Hash(key);
    if (hash == -1) return NULL;
    /* Look up and remove atomically */
    Py_ssize_t ix = _Py_dict_lookup(self, key, hash, &old_value);
    if (ix == DKIX_EMPTY) {
        if (default_value != NULL) return Py_NewRef(default_value);
        PyErr_SetObject(PyExc_KeyError, key);
        return NULL;
    }
    dict_delete_at(self, ix);
    return old_value;
}

dict.pop(key, default) looks up and removes in one operation, avoiding a double lookup. Raises KeyError if key is missing and no default is given.

dict.popitem

// CPython: Objects/dictobject.c:3440 dict_popitem_impl
static PyObject *
dict_popitem_impl(PyDictObject *self)
{
    /* Remove and return the last inserted item (LIFO since Python 3.7) */
    if (PyDict_GET_SIZE(self) == 0) {
        PyErr_SetString(PyExc_KeyError, "popitem(): dictionary is empty");
        return NULL;
    }
    /* Walk backwards through the entries to find the last non-dummy slot */
    Py_ssize_t i = self->ma_used - 1;
    ...
    return PyTuple_Pack(2, key, value);
}

dict.popitem() returns items in LIFO order (last inserted first) since Python 3.7. Used to process a dict while shrinking it.

View objects

// CPython: Objects/dictobject.c:3600 dictkeys_new
static PyObject *
dictkeys_new(PyObject *dict, PyObject *Py_UNUSED(ignored))
{
    /* Returns a view that reflects future changes to the dict */
    return _PyDictView_New(dict, &PyDictKeys_Type);
}

dict.keys(), dict.values(), and dict.items() return view objects that hold a reference to the underlying dict. Iterating a view while modifying the dict raises RuntimeError: dictionary changed size during iteration.

gopy notes

dict.pop is objects.DictPop in objects/dict_mutate.go. dict.popitem scans the entries array backwards. View objects are *objects.DictKeysView, *objects.DictValuesView, *objects.DictItemsView in objects/dict_iter.go. They hold a reference to the dict and version-check on each iteration step.