51 lines
1.2 KiB
ReStructuredText
51 lines
1.2 KiB
ReStructuredText
|
.. highlightlang:: c
|
||
|
|
|
||
|
|
.. _iterator:
|
||
|
|
|
||
|
|
Iterator Protocol
|
||
|
|
=================
|
||
|
|
|
||
|
|
.. versionadded:: 2.2
|
||
|
|
|
||
|
|
There are only a couple of functions specifically for working with iterators.
|
||
|
|
|
||
|
|
|
||
|
|
.. cfunction:: int PyIter_Check(PyObject *o)
|
||
|
|
|
||
|
|
Return true if the object *o* supports the iterator protocol.
|
||
|
|
|
||
|
|
|
||
|
|
.. cfunction:: PyObject* PyIter_Next(PyObject *o)
|
||
|
|
|
||
|
|
Return the next value from the iteration *o*. If the object is an iterator,
|
||
|
|
this retrieves the next value from the iteration, and returns *NULL* with no
|
||
|
|
exception set if there are no remaining items. If the object is not an
|
||
|
|
iterator, :exc:`TypeError` is raised, or if there is an error in 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 */
|
||
|
|
}
|