.. highlightlang:: 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

   .. index:: single: TupleType (in module types)

   This instance of :c:type:`PyTypeObject` represents the Python tuple type; it is
   the same object as ``tuple`` and ``types.TupleType`` 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.

   .. versionchanged:: 2.2
      Allowed subtypes to be accepted.


.. 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.

   .. versionadded:: 2.2


.. c:function:: PyObject* PyTuple_New(Py_ssize_t len)

   Return a new tuple object of size *len*, or *NULL* on failure.

   .. versionchanged:: 2.5
      This function used an :c:type:`int` type for *len*. This might require
      changes in your code for properly supporting 64-bit systems.


.. 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)``.

   .. versionadded:: 2.4

   .. versionchanged:: 2.5
      This function used an :c:type:`int` type for *n*. This might require
      changes in your code for properly supporting 64-bit systems.


.. c:function:: Py_ssize_t PyTuple_Size(PyObject *p)

   Take a pointer to a tuple object, and return the size of that tuple.

   .. versionchanged:: 2.5
      This function returned an :c:type:`int` type. This might require changes
      in your code for properly supporting 64-bit systems.


.. 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.

   .. versionchanged:: 2.5
      This function returned an :c:type:`int` type. This might require changes
      in your code for properly supporting 64-bit systems.


.. 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.

   .. versionchanged:: 2.5
      This function used an :c:type:`int` type for *pos*. This might require
      changes in your code for properly supporting 64-bit systems.


.. c:function:: PyObject* PyTuple_GET_ITEM(PyObject *p, Py_ssize_t pos)

   Like :c:func:`PyTuple_GetItem`, but does no checking of its arguments.

   .. versionchanged:: 2.5
      This function used an :c:type:`int` type for *pos*. This might require
      changes in your code for properly supporting 64-bit systems.


.. 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.

   .. versionchanged:: 2.5
      This function used an :c:type:`int` type for *low* and *high*. This might
      require changes in your code for properly supporting 64-bit systems.


.. 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.

   .. versionchanged:: 2.5
      This function used an :c:type:`int` type for *pos*. This might require
      changes in your code for properly supporting 64-bit systems.


.. 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.

   .. versionchanged:: 2.5
      This function used an :c:type:`int` type for *pos*. This might require
      changes in your code for properly supporting 64-bit systems.


.. 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`.

   .. versionchanged:: 2.2
      Removed unused third parameter, *last_is_sticky*.

   .. versionchanged:: 2.5
      This function used an :c:type:`int` type for *newsize*. This might
      require changes in your code for properly supporting 64-bit systems.


.. c:function:: int PyTuple_ClearFreeList()

   Clear the free list. Return the total number of freed items.

   .. versionadded:: 2.6