symbian-qemu-0.9.1-12/python-2.6.1/Doc/c-api/iter.rst
author johnathan.white@2718R8BGH51.accenture.com
Mon, 08 Mar 2010 18:45:03 +0000
changeset 46 b6935a90ca64
parent 1 2fb8b9db1c86
permissions -rw-r--r--
Modify framebuffer and NGA framebuffer to read screen size from board model dtb file. Optimise memory usuage of frame buffer Add example minigui application with hooks to profiler (which writes results to S:\). Modified NGA framebuffer to run its own dfc queue at high priority

.. 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 */
   }