author | andy simpson <andrews@symbian.org> |
Fri, 08 Oct 2010 16:52:59 +0100 | |
changeset 119 | 931f2bbaabf7 |
parent 1 | 2fb8b9db1c86 |
permissions | -rw-r--r-- |
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.. highlightlang:: c |
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.. _iterator: |
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Iterator Protocol |
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================= |
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.. versionadded:: 2.2 |
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There are only a couple of functions specifically for working with iterators. |
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.. cfunction:: int PyIter_Check(PyObject *o) |
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Return true if the object *o* supports the iterator protocol. |
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.. cfunction:: PyObject* PyIter_Next(PyObject *o) |
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Return the next value from the iteration *o*. If the object is an iterator, |
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this retrieves the next value from the iteration, and returns *NULL* with no |
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exception set if there are no remaining items. If the object is not an |
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iterator, :exc:`TypeError` is raised, or if there is an error in retrieving the |
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item, returns *NULL* and passes along the exception. |
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To write a loop which iterates over an iterator, the C code should look |
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something like this:: |
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PyObject *iterator = PyObject_GetIter(obj); |
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PyObject *item; |
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if (iterator == NULL) { |
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/* propagate error */ |
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} |
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while (item = PyIter_Next(iterator)) { |
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/* do something with item */ |
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... |
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/* release reference when done */ |
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Py_DECREF(item); |
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} |
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Py_DECREF(iterator); |
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if (PyErr_Occurred()) { |
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/* propagate error */ |
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} |
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else { |
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/* continue doing useful work */ |
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} |