1.. highlight:: c 2 3.. _mapping: 4 5Mapping Protocol 6================ 7 8See also :c:func:`PyObject_GetItem`, :c:func:`PyObject_SetItem` and 9:c:func:`PyObject_DelItem`. 10 11 12.. c:function:: int PyMapping_Check(PyObject *o) 13 14 Return ``1`` if the object provides mapping protocol or supports slicing, 15 and ``0`` otherwise. Note that it returns ``1`` for Python classes with 16 a :meth:`__getitem__` method since in general case it is impossible to 17 determine what type of keys it supports. This function always succeeds. 18 19 20.. c:function:: Py_ssize_t PyMapping_Size(PyObject *o) 21 Py_ssize_t PyMapping_Length(PyObject *o) 22 23 .. index:: builtin: len 24 25 Returns the number of keys in object *o* on success, and ``-1`` on failure. 26 This is equivalent to the Python expression ``len(o)``. 27 28 29.. c:function:: PyObject* PyMapping_GetItemString(PyObject *o, const char *key) 30 31 Return element of *o* corresponding to the string *key* or ``NULL`` on failure. 32 This is the equivalent of the Python expression ``o[key]``. 33 See also :c:func:`PyObject_GetItem`. 34 35 36.. c:function:: int PyMapping_SetItemString(PyObject *o, const char *key, PyObject *v) 37 38 Map the string *key* to the value *v* in object *o*. Returns ``-1`` on 39 failure. This is the equivalent of the Python statement ``o[key] = v``. 40 See also :c:func:`PyObject_SetItem`. This function *does not* steal a 41 reference to *v*. 42 43 44.. c:function:: int PyMapping_DelItem(PyObject *o, PyObject *key) 45 46 Remove the mapping for the object *key* from the object *o*. Return ``-1`` 47 on failure. This is equivalent to the Python statement ``del o[key]``. 48 This is an alias of :c:func:`PyObject_DelItem`. 49 50 51.. c:function:: int PyMapping_DelItemString(PyObject *o, const char *key) 52 53 Remove the mapping for the string *key* from the object *o*. Return ``-1`` 54 on failure. This is equivalent to the Python statement ``del o[key]``. 55 56 57.. c:function:: int PyMapping_HasKey(PyObject *o, PyObject *key) 58 59 Return ``1`` if the mapping object has the key *key* and ``0`` otherwise. 60 This is equivalent to the Python expression ``key in o``. 61 This function always succeeds. 62 63 Note that exceptions which occur while calling the :meth:`__getitem__` 64 method will get suppressed. 65 To get error reporting use :c:func:`PyObject_GetItem()` instead. 66 67 68.. c:function:: int PyMapping_HasKeyString(PyObject *o, const char *key) 69 70 Return ``1`` if the mapping object has the key *key* and ``0`` otherwise. 71 This is equivalent to the Python expression ``key in o``. 72 This function always succeeds. 73 74 Note that exceptions which occur while calling the :meth:`__getitem__` 75 method and creating a temporary string object will get suppressed. 76 To get error reporting use :c:func:`PyMapping_GetItemString()` instead. 77 78 79.. c:function:: PyObject* PyMapping_Keys(PyObject *o) 80 81 On success, return a list of the keys in object *o*. On failure, return 82 ``NULL``. 83 84 .. versionchanged:: 3.7 85 Previously, the function returned a list or a tuple. 86 87 88.. c:function:: PyObject* PyMapping_Values(PyObject *o) 89 90 On success, return a list of the values in object *o*. On failure, return 91 ``NULL``. 92 93 .. versionchanged:: 3.7 94 Previously, the function returned a list or a tuple. 95 96 97.. c:function:: PyObject* PyMapping_Items(PyObject *o) 98 99 On success, return a list of the items in object *o*, where each item is a 100 tuple containing a key-value pair. On failure, return ``NULL``. 101 102 .. versionchanged:: 3.7 103 Previously, the function returned a list or a tuple. 104