[Python-checkins] cpython (3.5): Issue #25701: Document C API functions that both set and delete objects
martin.panter
python-checkins at python.org
Mon Dec 7 19:07:30 EST 2015
https://hg.python.org/cpython/rev/50711c80ff76
changeset: 99504:50711c80ff76
branch: 3.5
parent: 99502:e10e3fd31726
user: Martin Panter <vadmium+py at gmail.com>
date: Tue Dec 08 00:03:20 2015 +0000
summary:
Issue #25701: Document C API functions that both set and delete objects
Also document that the separate functions that delete objects are preferred;
using PyObject_SetAttr(), _SetAttrString(), and PySequence_SetItem() to
delete is deprecated.
files:
Doc/c-api/object.rst | 27 +++++++++++++++++++--------
Doc/c-api/sequence.rst | 6 +++++-
Doc/c-api/typeobj.rst | 26 ++++++++++++++++----------
Include/abstract.h | 20 ++++++++++----------
4 files changed, 50 insertions(+), 29 deletions(-)
diff --git a/Doc/c-api/object.rst b/Doc/c-api/object.rst
--- a/Doc/c-api/object.rst
+++ b/Doc/c-api/object.rst
@@ -68,25 +68,35 @@
.. c:function:: int PyObject_SetAttr(PyObject *o, PyObject *attr_name, PyObject *v)
Set the value of the attribute named *attr_name*, for object *o*, to the value
- *v*. Returns ``-1`` on failure. This is the equivalent of the Python statement
+ *v*. Raise an exception and return ``-1`` on failure;
+ return ``0`` on success. This is the equivalent of the Python statement
``o.attr_name = v``.
+ If *v* is *NULL*, the attribute is deleted, however this feature is
+ deprecated in favour of using :c:func:`PyObject_DelAttr`.
+
.. c:function:: int PyObject_SetAttrString(PyObject *o, const char *attr_name, PyObject *v)
Set the value of the attribute named *attr_name*, for object *o*, to the value
- *v*. Returns ``-1`` on failure. This is the equivalent of the Python statement
+ *v*. Raise an exception and return ``-1`` on failure;
+ return ``0`` on success. This is the equivalent of the Python statement
``o.attr_name = v``.
+ If *v* is *NULL*, the attribute is deleted, however this feature is
+ deprecated in favour of using :c:func:`PyObject_DelAttrString`.
+
.. c:function:: int PyObject_GenericSetAttr(PyObject *o, PyObject *name, PyObject *value)
- Generic attribute setter function that is meant to be put into a type
- object's ``tp_setattro`` slot. It looks for a data descriptor in the
+ Generic attribute setter and deleter function that is meant
+ to be put into a type object's :c:member:`~PyTypeObject.tp_setattro`
+ slot. It looks for a data descriptor in the
dictionary of classes in the object's MRO, and if found it takes preference
- over setting the attribute in the instance dictionary. Otherwise, the
- attribute is set in the object's :attr:`~object.__dict__` (if present).
- Otherwise, an :exc:`AttributeError` is raised and ``-1`` is returned.
+ over setting or deleting the attribute in the instance dictionary. Otherwise, the
+ attribute is set or deleted in the object's :attr:`~object.__dict__` (if present).
+ On success, ``0`` is returned, otherwise an :exc:`AttributeError`
+ is raised and ``-1`` is returned.
.. c:function:: int PyObject_DelAttr(PyObject *o, PyObject *attr_name)
@@ -378,7 +388,8 @@
.. c:function:: int PyObject_SetItem(PyObject *o, PyObject *key, PyObject *v)
- Map the object *key* to the value *v*. Returns ``-1`` on failure. This is the
+ Map the object *key* to the value *v*. Raise an exception and
+ return ``-1`` on failure; return ``0`` on success. This is the
equivalent of the Python statement ``o[key] = v``.
diff --git a/Doc/c-api/sequence.rst b/Doc/c-api/sequence.rst
--- a/Doc/c-api/sequence.rst
+++ b/Doc/c-api/sequence.rst
@@ -62,10 +62,14 @@
.. c:function:: int PySequence_SetItem(PyObject *o, Py_ssize_t i, PyObject *v)
- Assign object *v* to the *i*\ th element of *o*. Returns ``-1`` on failure. This
+ Assign object *v* to the *i*\ th element of *o*. Raise an exception
+ and return ``-1`` on failure; return ``0`` on success. This
is the equivalent of the Python statement ``o[i] = v``. This function *does
not* steal a reference to *v*.
+ If *v* is *NULL*, the element is deleted, however this feature is
+ deprecated in favour of using :c:func:`PySequence_DelItem`.
+
.. c:function:: int PySequence_DelItem(PyObject *o, Py_ssize_t i)
diff --git a/Doc/c-api/typeobj.rst b/Doc/c-api/typeobj.rst
--- a/Doc/c-api/typeobj.rst
+++ b/Doc/c-api/typeobj.rst
@@ -208,12 +208,13 @@
.. c:member:: setattrfunc PyTypeObject.tp_setattr
- An optional pointer to the set-attribute-string function.
+ An optional pointer to the function for setting and deleting attributes.
This field is deprecated. When it is defined, it should point to a function
that acts the same as the :c:member:`~PyTypeObject.tp_setattro` function, but taking a C string
instead of a Python string object to give the attribute name. The signature is
- the same as for :c:func:`PyObject_SetAttrString`.
+ the same as for :c:func:`PyObject_SetAttrString`, but setting
+ *v* to *NULL* to delete an attribute must be supported.
This field is inherited by subtypes together with :c:member:`~PyTypeObject.tp_setattro`: a subtype
inherits both :c:member:`~PyTypeObject.tp_setattr` and :c:member:`~PyTypeObject.tp_setattro` from its base type when
@@ -351,9 +352,10 @@
.. c:member:: setattrofunc PyTypeObject.tp_setattro
- An optional pointer to the set-attribute function.
+ An optional pointer to the function for setting and deleting attributes.
- The signature is the same as for :c:func:`PyObject_SetAttr`. It is usually
+ The signature is the same as for :c:func:`PyObject_SetAttr`, but setting
+ *v* to *NULL* to delete an attribute must be supported. It is usually
convenient to set this field to :c:func:`PyObject_GenericSetAttr`, which
implements the normal way of setting object attributes.
@@ -724,7 +726,7 @@
typedef struct PyGetSetDef {
char *name; /* attribute name */
getter get; /* C function to get the attribute */
- setter set; /* C function to set the attribute */
+ setter set; /* C function to set or delete the attribute */
char *doc; /* optional doc string */
void *closure; /* optional additional data for getter and setter */
} PyGetSetDef;
@@ -775,12 +777,14 @@
.. c:member:: descrsetfunc PyTypeObject.tp_descr_set
- An optional pointer to a "descriptor set" function.
+ An optional pointer to a function for setting and deleting
+ a descriptor's value.
The function signature is ::
int tp_descr_set(PyObject *self, PyObject *obj, PyObject *value);
+ The *value* argument is set to *NULL* to delete the value.
This field is inherited by subtypes.
.. XXX explain.
@@ -1171,9 +1175,11 @@
.. c:member:: objobjargproc PyMappingMethods.mp_ass_subscript
- This function is used by :c:func:`PyObject_SetItem` and has the same
- signature. If this slot is *NULL*, the object does not support item
- assignment.
+ This function is used by :c:func:`PyObject_SetItem` and
+ :c:func:`PyObject_DelItem`. It has the same signature as
+ :c:func:`PyObject_SetItem`, but *v* can also be set to *NULL* to delete
+ an item. If this slot is *NULL*, the object does not support item
+ assignment and deletion.
.. _sequence-structs:
@@ -1222,7 +1228,7 @@
This function is used by :c:func:`PySequence_SetItem` and has the same
signature. This slot may be left to *NULL* if the object does not support
- item assignment.
+ item assignment and deletion.
.. c:member:: objobjproc PySequenceMethods.sq_contains
diff --git a/Include/abstract.h b/Include/abstract.h
--- a/Include/abstract.h
+++ b/Include/abstract.h
@@ -192,8 +192,8 @@
int PyObject_SetAttrString(PyObject *o, const char *attr_name, PyObject *v);
Set the value of the attribute named attr_name, for object o,
- to the value, v. Returns -1 on failure. This is
- the equivalent of the Python statement: o.attr_name=v.
+ to the value v. Raise an exception and return -1 on failure; return 0 on
+ success. This is the equivalent of the Python statement o.attr_name=v.
*/
@@ -202,8 +202,8 @@
int PyObject_SetAttr(PyObject *o, PyObject *attr_name, PyObject *v);
Set the value of the attribute named attr_name, for object o,
- to the value, v. Returns -1 on failure. This is
- the equivalent of the Python statement: o.attr_name=v.
+ to the value v. Raise an exception and return -1 on failure; return 0 on
+ success. This is the equivalent of the Python statement o.attr_name=v.
*/
@@ -435,9 +435,9 @@
PyAPI_FUNC(int) PyObject_SetItem(PyObject *o, PyObject *key, PyObject *v);
/*
- Map the object, key, to the value, v. Returns
- -1 on failure. This is the equivalent of the Python
- statement: o[key]=v.
+ Map the object key to the value v. Raise an exception and return -1
+ on failure; return 0 on success. This is the equivalent of the Python
+ statement o[key]=v.
*/
PyAPI_FUNC(int) PyObject_DelItemString(PyObject *o, const char *key);
@@ -993,9 +993,9 @@
PyAPI_FUNC(int) PySequence_SetItem(PyObject *o, Py_ssize_t i, PyObject *v);
/*
- Assign object v to the ith element of o. Returns
- -1 on failure. This is the equivalent of the Python
- statement: o[i]=v.
+ Assign object v to the ith element of o. Raise an exception and return
+ -1 on failure; return 0 on success. This is the equivalent of the
+ Python statement o[i]=v.
*/
PyAPI_FUNC(int) PySequence_DelItem(PyObject *o, Py_ssize_t i);
--
Repository URL: https://hg.python.org/cpython
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