Python/docs/3.10/c-api/iter

Iterator Protocol

There are two functions specifically for working with iterators.

int PyIter_Check(PyObject *o)

Return non-zero if the object o can be safely passed to PyIter_Next(), and 0 otherwise. This function always succeeds.

int PyAIter_Check(PyObject *o)

Returns non-zero if the object ‘obj’ provides AsyncIterator protocols, and 0 otherwise. This function always succeeds.

New in version 3.10.

PyObject *PyIter_Next(PyObject *o)

Return the next value from the iterator o. The object must be an iterator according to 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.

To write a loop which iterates over an iterator, the C code should look something like this:

PyObject *iterator = PyObject_GetIter(obj);
PyObject *item;

if (iterator == NULL) {
    /* propagate error */
}

while ((item = PyIter_Next(iterator))) {
    /* do something with item */
    ...
    /* release reference when done */
    Py_DECREF(item);
}

Py_DECREF(iterator);

if (PyErr_Occurred()) {
    /* propagate error */
}
else {
    /* continue doing useful work */
}

type PySendResult

The enum value used to represent different results of PyIter_Send().

New in version 3.10.

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.

New in version 3.10.