mirror of https://github.com/python/cpython
233 lines
9.0 KiB
ReStructuredText
233 lines
9.0 KiB
ReStructuredText
.. highlight:: c
|
|
|
|
.. _tupleobjects:
|
|
|
|
Tuple Objects
|
|
-------------
|
|
|
|
.. index:: pair: 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. This function always succeeds.
|
|
|
|
|
|
.. 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. This function always succeeds.
|
|
|
|
|
|
.. 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
|
|
negative or 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 tuple 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.
|
|
|
|
Bounds checking is performed as an assertion if Python is built in
|
|
:ref:`debug mode <debug-build>` or :option:`with assertions <--with-assertions>`.
|
|
|
|
.. note::
|
|
|
|
This function "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:expr:`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*.
|
|
|
|
Bounds checking is performed as an assertion if Python is built in
|
|
:ref:`debug mode <debug-build>` or :option:`with assertions <--with-assertions>`.
|
|
|
|
|
|
.. c:function:: PyObject* PyStructSequence_GET_ITEM(PyObject *p, Py_ssize_t pos)
|
|
|
|
Alias to :c:func:`PyStructSequence_GetItem`.
|
|
|
|
.. versionchanged:: 3.13
|
|
Now implemented as an alias to :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.
|
|
|
|
Bounds checking is performed as an assertion if Python is built in
|
|
:ref:`debug mode <debug-build>` or :option:`with assertions <--with-assertions>`.
|
|
|
|
.. note::
|
|
|
|
This function "steals" a reference to *o*.
|
|
|
|
|
|
.. c:function:: void PyStructSequence_SET_ITEM(PyObject *p, Py_ssize_t *pos, PyObject *o)
|
|
|
|
Alias to :c:func:`PyStructSequence_SetItem`.
|
|
|
|
.. versionchanged:: 3.13
|
|
Now implemented as an alias to :c:func:`PyStructSequence_SetItem`.
|