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cpython/Doc/c-api/iter.rst
Erlend E. Aasland e006c7371d
gh-105201: Add PyIter_NextItem() (#122331)
Return -1 and set an exception on error; return 0 if the iterator is
exhausted, and return 1 if the next item was fetched successfully.

Prefer this API to PyIter_Next(), which requires the caller to use
PyErr_Occurred() to differentiate between iterator exhaustion and errors.

Co-authered-by: Irit Katriel <iritkatriel@yahoo.com>
2024-08-08 00:47:15 +02:00

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.. highlight:: c
.. _iterator:
Iterator Protocol
=================
There are two functions specifically for working with iterators.
.. c:function:: int PyIter_Check(PyObject *o)
Return non-zero if the object *o* can be safely passed to
:c:func:`PyIter_NextItem` and ``0`` otherwise.
This function always succeeds.
.. c:function:: int PyAIter_Check(PyObject *o)
Return non-zero if the object *o* provides the :class:`AsyncIterator`
protocol, and ``0`` otherwise. This function always succeeds.
.. versionadded:: 3.10
.. c:function:: int PyIter_NextItem(PyObject *iter, PyObject **item)
Return ``1`` and set *item* to a :term:`strong reference` of the
next value of the iterator *iter* on success.
Return ``0`` and set *item* to ``NULL`` if there are no remaining values.
Return ``-1``, set *item* to ``NULL`` and set an exception on error.
.. versionadded:: 3.14
.. c:function:: PyObject* PyIter_Next(PyObject *o)
This is an older version of :c:func:`!PyIter_NextItem`,
which is retained for backwards compatibility.
Prefer :c:func:`PyIter_NextItem`.
Return the next value from the iterator *o*. The object must be an iterator
according to :c:func:`PyIter_Check` (it is up to the caller to check this).
If there are no remaining values, returns ``NULL`` with no exception set.
If an error occurs while retrieving the item, returns ``NULL`` and passes
along the exception.
.. c:type:: PySendResult
The enum value used to represent different results of :c:func:`PyIter_Send`.
.. versionadded:: 3.10
.. c:function:: PySendResult PyIter_Send(PyObject *iter, PyObject *arg, PyObject **presult)
Sends the *arg* value into the iterator *iter*. Returns:
- ``PYGEN_RETURN`` if iterator returns. Return value is returned via *presult*.
- ``PYGEN_NEXT`` if iterator yields. Yielded value is returned via *presult*.
- ``PYGEN_ERROR`` if iterator has raised and exception. *presult* is set to ``NULL``.
.. versionadded:: 3.10