| .. highlightlang:: c |
| |
| .. _dictobjects: |
| |
| Dictionary Objects |
| ------------------ |
| |
| .. index:: object: dictionary |
| |
| |
| .. ctype:: PyDictObject |
| |
| This subtype of :ctype:`PyObject` represents a Python dictionary object. |
| |
| |
| .. cvar:: PyTypeObject PyDict_Type |
| |
| .. index:: |
| single: DictType (in module types) |
| single: DictionaryType (in module types) |
| |
| This instance of :ctype:`PyTypeObject` represents the Python dictionary type. |
| This is exposed to Python programs as ``dict`` and ``types.DictType``. |
| |
| |
| .. cfunction:: int PyDict_Check(PyObject *p) |
| |
| Return true if *p* is a dict object or an instance of a subtype of the dict |
| type. |
| |
| |
| .. cfunction:: int PyDict_CheckExact(PyObject *p) |
| |
| Return true if *p* is a dict object, but not an instance of a subtype of the |
| dict type. |
| |
| |
| .. cfunction:: PyObject* PyDict_New() |
| |
| Return a new empty dictionary, or *NULL* on failure. |
| |
| |
| .. cfunction:: PyObject* PyDictProxy_New(PyObject *dict) |
| |
| Return a proxy object for a mapping which enforces read-only behavior. This is |
| normally used to create a proxy to prevent modification of the dictionary for |
| non-dynamic class types. |
| |
| |
| .. cfunction:: void PyDict_Clear(PyObject *p) |
| |
| Empty an existing dictionary of all key-value pairs. |
| |
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| .. cfunction:: int PyDict_Contains(PyObject *p, PyObject *key) |
| |
| Determine if dictionary *p* contains *key*. If an item in *p* is matches *key*, |
| return ``1``, otherwise return ``0``. On error, return ``-1``. This is |
| equivalent to the Python expression ``key in p``. |
| |
| |
| .. cfunction:: PyObject* PyDict_Copy(PyObject *p) |
| |
| Return a new dictionary that contains the same key-value pairs as *p*. |
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| .. cfunction:: int PyDict_SetItem(PyObject *p, PyObject *key, PyObject *val) |
| |
| Insert *value* into the dictionary *p* with a key of *key*. *key* must be |
| :term:`hashable`; if it isn't, :exc:`TypeError` will be raised. Return ``0`` |
| on success or ``-1`` on failure. |
| |
| |
| .. cfunction:: int PyDict_SetItemString(PyObject *p, const char *key, PyObject *val) |
| |
| .. index:: single: PyString_FromString() |
| |
| Insert *value* into the dictionary *p* using *key* as a key. *key* should be a |
| :ctype:`char\*`. The key object is created using ``PyString_FromString(key)``. |
| Return ``0`` on success or ``-1`` on failure. |
| |
| |
| .. cfunction:: int PyDict_DelItem(PyObject *p, PyObject *key) |
| |
| Remove the entry in dictionary *p* with key *key*. *key* must be hashable; if it |
| isn't, :exc:`TypeError` is raised. Return ``0`` on success or ``-1`` on |
| failure. |
| |
| |
| .. cfunction:: int PyDict_DelItemString(PyObject *p, char *key) |
| |
| Remove the entry in dictionary *p* which has a key specified by the string |
| *key*. Return ``0`` on success or ``-1`` on failure. |
| |
| |
| .. cfunction:: PyObject* PyDict_GetItem(PyObject *p, PyObject *key) |
| |
| Return the object from dictionary *p* which has a key *key*. Return *NULL* if |
| the key *key* is not present, but *without* setting an exception. |
| |
| |
| .. cfunction:: PyObject* PyDict_GetItemWithError(PyObject *p, PyObject *key) |
| |
| Variant of :cfunc:`PyDict_GetItem` that does not suppress |
| exceptions. Return *NULL* **with** an exception set if an exception |
| occurred. Return *NULL* **without** an exception set if the key |
| wasn't present. |
| |
| |
| .. cfunction:: PyObject* PyDict_GetItemString(PyObject *p, const char *key) |
| |
| This is the same as :cfunc:`PyDict_GetItem`, but *key* is specified as a |
| :ctype:`char\*`, rather than a :ctype:`PyObject\*`. |
| |
| |
| .. cfunction:: PyObject* PyDict_Items(PyObject *p) |
| |
| Return a :ctype:`PyListObject` containing all the items from the dictionary, as |
| in the dictionary method :meth:`dict.items`. |
| |
| |
| .. cfunction:: PyObject* PyDict_Keys(PyObject *p) |
| |
| Return a :ctype:`PyListObject` containing all the keys from the dictionary, as |
| in the dictionary method :meth:`dict.keys`. |
| |
| |
| .. cfunction:: PyObject* PyDict_Values(PyObject *p) |
| |
| Return a :ctype:`PyListObject` containing all the values from the dictionary |
| *p*, as in the dictionary method :meth:`dict.values`. |
| |
| |
| .. cfunction:: Py_ssize_t PyDict_Size(PyObject *p) |
| |
| .. index:: builtin: len |
| |
| Return the number of items in the dictionary. This is equivalent to ``len(p)`` |
| on a dictionary. |
| |
| |
| .. cfunction:: int PyDict_Next(PyObject *p, Py_ssize_t *ppos, PyObject **pkey, PyObject **pvalue) |
| |
| Iterate over all key-value pairs in the dictionary *p*. The :ctype:`int` |
| 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 :ctype:`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. |
| |
| For example:: |
| |
| 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); |
| } |
| |
| |
| .. cfunction:: int PyDict_Merge(PyObject *a, PyObject *b, int override) |
| |
| Iterate over mapping object *b* adding key-value pairs to dictionary *a*. *b* |
| may be a dictionary, or any object supporting :func:`PyMapping_Keys` and |
| :func:`PyObject_GetItem`. If *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*. Return ``0`` on success or ``-1`` if an |
| exception was raised. |
| |
| |
| .. cfunction:: int PyDict_Update(PyObject *a, PyObject *b) |
| |
| This is the same as ``PyDict_Merge(a, b, 1)`` in C, or ``a.update(b)`` in |
| Python. Return ``0`` on success or ``-1`` if an exception was raised. |
| |
| |
| .. cfunction:: int PyDict_MergeFromSeq2(PyObject *a, PyObject *seq2, int override) |
| |
| 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`` on success or ``-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 |