.. highlightlang:: c

.. _slice-objects:

Slice Objects
-------------


.. cvar:: PyTypeObject PySlice_Type

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

   The type object for slice objects.  This is the same as ``slice`` and
   ``types.SliceType``.


.. cfunction:: int PySlice_Check(PyObject *ob)

   Return true if *ob* is a slice object; *ob* must not be *NULL*.


.. cfunction:: PyObject* PySlice_New(PyObject *start, PyObject *stop, PyObject *step)

   Return a new slice object with the given values.  The *start*, *stop*, and
   *step* parameters are used as the values of the slice object attributes of the
   same names.  Any of the values may be *NULL*, in which case the ``None`` will be
   used for the corresponding attribute.  Return *NULL* if the new object could not
   be allocated.


.. cfunction:: int PySlice_GetIndices(PySliceObject *slice, Py_ssize_t length, Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step)

   Retrieve the start, stop and step indices from the slice object *slice*,
   assuming a sequence of length *length*. Treats indices greater than *length* as
   errors.

   Returns 0 on success and -1 on error with no exception set (unless one of the
   indices was not :const:`None` and failed to be converted to an integer, in which
   case -1 is returned with an exception set).

   You probably do not want to use this function.  If you want to use slice objects
   in versions of Python prior to 2.3, you would probably do well to incorporate
   the source of :cfunc:`PySlice_GetIndicesEx`, suitably renamed, in the source of
   your extension.


.. cfunction:: int PySlice_GetIndicesEx(PySliceObject *slice, Py_ssize_t length, Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step, Py_ssize_t *slicelength)

   Usable replacement for :cfunc:`PySlice_GetIndices`.  Retrieve the start, stop,
   and step indices from the slice object *slice* assuming a sequence of length
   *length*, and store the length of the slice in *slicelength*.  Out of bounds
   indices are clipped in a manner consistent with the handling of normal slices.

   Returns 0 on success and -1 on error with exception set.

   .. versionadded:: 2.3