cpython/Doc/c-api/tuple.rst
Victor Stinner 8f88190af5
[3.9] bpo-40204: Allow pre-Sphinx 3 syntax in the doc (GH-21844) (GH-21901)
* bpo-40204: Allow pre-Sphinx 3 syntax in the doc (GH-21844)

Enable Sphinx 3.2 "c_allow_pre_v3" option and disable the
c_warn_on_allowed_pre_v3 option to make the documentation compatible
with Sphinx 2 and Sphinx 3.

(cherry picked from commit 423e77d6de)

* bpo-40204: Fix Sphinx sytanx in howto/instrumentation.rst (GH-21858)

Use generic '.. object::' to declare markers, rather than abusing
'..  c:function::' which fails on Sphinx 3.

(cherry picked from commit 43577c01a2)

* bpo-40204: Fix duplicates in the documentation (GH-21857)

Fix two Sphinx 3 issues:

Doc/c-api/buffer.rst:304: WARNING: Duplicate C declaration, also defined in 'c-api/buffer'.
Declaration is 'PyBUF_ND'.

Doc/c-api/unicode.rst:1603: WARNING: Duplicate C declaration, also defined in 'c-api/unicode'.
Declaration is 'PyObject* PyUnicode_Translate(PyObject *str, PyObject *table, const char *errors)'.

(cherry picked from commit 46d10b1237)

* bpo-40204: Add :noindex: in the documentation (GH-21859)

Add :noindex: to duplicated documentation to fix "duplicate object
description" errors.

For example, fix this Sphinx 3 issue:

Doc/library/configparser.rst:1146: WARNING: duplicate object
description of configparser.ConfigParser.optionxform, other instance
in library/configparser, use :noindex: for one of them

(cherry picked from commit d3ded08048)

* bpo-40204, doc: Fix syntax of C variables (GH-21846)

For example, fix the following Sphinx 3 errors:

Doc/c-api/buffer.rst:102: WARNING: Error in declarator or parameters
Invalid C declaration: Expected identifier in nested name. [error at 5]
  void \*obj
  -----^

Doc/c-api/arg.rst:130: WARNING: Unparseable C cross-reference: 'PyObject*'
Invalid C declaration: Expected end of definition. [error at 8]
  PyObject*
  --------^

The modified documentation is compatible with Sphinx 2 and Sphinx 3.

(cherry picked from commit 474652fe93)

* bpo-40204: Fix reference to terms in the doc (GH-21865)

Sphinx 3 requires to refer to terms with the exact case.

For example, fix the Sphinx 3 warning:

Doc/library/pkgutil.rst:71: WARNING: term Loader not found in case
sensitive match.made a reference to loader instead.

(cherry picked from commit bb0b08540c)

* bpo-40204: Fix duplicated productionlist names in the doc (GH-21900)

Sphinx 3 disallows having more than one productionlist markup with
the same name. Simply remove names in this case, since names are not
shown anyway. For example, fix the Sphinx 3 warning:

Doc/reference/introduction.rst:96: duplicate token description
of *:name, other instance in reference/expressions

(cherry picked from commit 1abeda80f7)
2020-08-19 19:25:22 +02:00

222 lines
8.4 KiB
ReStructuredText

.. highlight:: c
.. _tupleobjects:
Tuple Objects
-------------
.. index:: object: tuple
.. c:type:: PyTupleObject
This subtype of :c:type:`PyObject` represents a Python tuple object.
.. c:var:: PyTypeObject PyTuple_Type
This instance of :c:type:`PyTypeObject` represents the Python tuple type; it
is the same object as :class:`tuple` in the Python layer.
.. c:function:: int PyTuple_Check(PyObject *p)
Return true if *p* is a tuple object or an instance of a subtype of the tuple
type.
.. c:function:: int PyTuple_CheckExact(PyObject *p)
Return true if *p* is a tuple object, but not an instance of a subtype of the
tuple type.
.. c:function:: PyObject* PyTuple_New(Py_ssize_t len)
Return a new tuple object of size *len*, or ``NULL`` on failure.
.. c:function:: PyObject* PyTuple_Pack(Py_ssize_t n, ...)
Return a new tuple object of size *n*, or ``NULL`` on failure. The tuple values
are initialized to the subsequent *n* C arguments pointing to Python objects.
``PyTuple_Pack(2, a, b)`` is equivalent to ``Py_BuildValue("(OO)", a, b)``.
.. c:function:: Py_ssize_t PyTuple_Size(PyObject *p)
Take a pointer to a tuple object, and return the size of that tuple.
.. c:function:: Py_ssize_t PyTuple_GET_SIZE(PyObject *p)
Return the size of the tuple *p*, which must be non-``NULL`` and point to a tuple;
no error checking is performed.
.. c:function:: PyObject* PyTuple_GetItem(PyObject *p, Py_ssize_t pos)
Return the object at position *pos* in the tuple pointed to by *p*. If *pos* is
out of bounds, return ``NULL`` and set an :exc:`IndexError` exception.
.. c:function:: PyObject* PyTuple_GET_ITEM(PyObject *p, Py_ssize_t pos)
Like :c:func:`PyTuple_GetItem`, but does no checking of its arguments.
.. c:function:: PyObject* PyTuple_GetSlice(PyObject *p, Py_ssize_t low, Py_ssize_t high)
Return the slice of the tuple pointed to by *p* between *low* and *high*,
or ``NULL`` on failure. This is the equivalent of the Python expression
``p[low:high]``. Indexing from the end of the list is not supported.
.. c:function:: int PyTuple_SetItem(PyObject *p, Py_ssize_t pos, PyObject *o)
Insert a reference to object *o* at position *pos* of the tuple pointed to by
*p*. Return ``0`` on success. If *pos* is out of bounds, return ``-1``
and set an :exc:`IndexError` exception.
.. note::
This function "steals" a reference to *o* and discards a reference to
an item already in the tuple at the affected position.
.. c:function:: void PyTuple_SET_ITEM(PyObject *p, Py_ssize_t pos, PyObject *o)
Like :c:func:`PyTuple_SetItem`, but does no error checking, and should *only* be
used to fill in brand new tuples.
.. note::
This macro "steals" a reference to *o*, and, unlike
:c:func:`PyTuple_SetItem`, does *not* discard a reference to any item that
is being replaced; any reference in the tuple at position *pos* will be
leaked.
.. c:function:: int _PyTuple_Resize(PyObject **p, Py_ssize_t newsize)
Can be used to resize a tuple. *newsize* will be the new length of the tuple.
Because tuples are *supposed* to be immutable, this should only be used if there
is only one reference to the object. Do *not* use this if the tuple may already
be known to some other part of the code. The tuple will always grow or shrink
at the end. Think of this as destroying the old tuple and creating a new one,
only more efficiently. Returns ``0`` on success. Client code should never
assume that the resulting value of ``*p`` will be the same as before calling
this function. If the object referenced by ``*p`` is replaced, the original
``*p`` is destroyed. On failure, returns ``-1`` and sets ``*p`` to ``NULL``, and
raises :exc:`MemoryError` or :exc:`SystemError`.
Struct Sequence Objects
-----------------------
Struct sequence objects are the C equivalent of :func:`~collections.namedtuple`
objects, i.e. a sequence whose items can also be accessed through attributes.
To create a struct sequence, you first have to create a specific struct sequence
type.
.. c:function:: PyTypeObject* PyStructSequence_NewType(PyStructSequence_Desc *desc)
Create a new struct sequence type from the data in *desc*, described below. Instances
of the resulting type can be created with :c:func:`PyStructSequence_New`.
.. c:function:: void PyStructSequence_InitType(PyTypeObject *type, PyStructSequence_Desc *desc)
Initializes a struct sequence type *type* from *desc* in place.
.. c:function:: int PyStructSequence_InitType2(PyTypeObject *type, PyStructSequence_Desc *desc)
The same as ``PyStructSequence_InitType``, but returns ``0`` on success and ``-1`` on
failure.
.. versionadded:: 3.4
.. c:type:: PyStructSequence_Desc
Contains the meta information of a struct sequence type to create.
+-------------------+------------------------------+--------------------------------------+
| Field | C Type | Meaning |
+===================+==============================+======================================+
| ``name`` | ``const char *`` | name of the struct sequence type |
+-------------------+------------------------------+--------------------------------------+
| ``doc`` | ``const char *`` | pointer to docstring for the type |
| | | or ``NULL`` to omit |
+-------------------+------------------------------+--------------------------------------+
| ``fields`` | ``PyStructSequence_Field *`` | pointer to ``NULL``-terminated array |
| | | with field names of the new type |
+-------------------+------------------------------+--------------------------------------+
| ``n_in_sequence`` | ``int`` | number of fields visible to the |
| | | Python side (if used as tuple) |
+-------------------+------------------------------+--------------------------------------+
.. c:type:: PyStructSequence_Field
Describes a field of a struct sequence. As a struct sequence is modeled as a
tuple, all fields are typed as :c:type:`PyObject*`. The index in the
:attr:`fields` array of the :c:type:`PyStructSequence_Desc` determines which
field of the struct sequence is described.
+-----------+------------------+-----------------------------------------+
| Field | C Type | Meaning |
+===========+==================+=========================================+
| ``name`` | ``const char *`` | name for the field or ``NULL`` to end |
| | | the list of named fields, set to |
| | | :c:data:`PyStructSequence_UnnamedField` |
| | | to leave unnamed |
+-----------+------------------+-----------------------------------------+
| ``doc`` | ``const char *`` | field docstring or ``NULL`` to omit |
+-----------+------------------+-----------------------------------------+
.. c:var:: const char * const PyStructSequence_UnnamedField
Special value for a field name to leave it unnamed.
.. versionchanged:: 3.9
The type was changed from ``char *``.
.. c:function:: PyObject* PyStructSequence_New(PyTypeObject *type)
Creates an instance of *type*, which must have been created with
:c:func:`PyStructSequence_NewType`.
.. c:function:: PyObject* PyStructSequence_GetItem(PyObject *p, Py_ssize_t pos)
Return the object at position *pos* in the struct sequence pointed to by *p*.
No bounds checking is performed.
.. c:function:: PyObject* PyStructSequence_GET_ITEM(PyObject *p, Py_ssize_t pos)
Macro equivalent of :c:func:`PyStructSequence_GetItem`.
.. c:function:: void PyStructSequence_SetItem(PyObject *p, Py_ssize_t pos, PyObject *o)
Sets the field at index *pos* of the struct sequence *p* to value *o*. Like
:c:func:`PyTuple_SET_ITEM`, this should only be used to fill in brand new
instances.
.. note::
This function "steals" a reference to *o*.
.. c:function:: void PyStructSequence_SET_ITEM(PyObject *p, Py_ssize_t *pos, PyObject *o)
Macro equivalent of :c:func:`PyStructSequence_SetItem`.
.. note::
This function "steals" a reference to *o*.