15.20 处理C语言中的可迭代对象

问题¶

You want to write C extension code that consumes items from any iterable object such as a list, tuple, file, or generator.

解决方案¶

Here is a sample C extension function that shows how to consume the items on an iterable:

static PyObject *py_consume_iterable(PyObject *self, PyObject *args) {

PyObject *obj; PyObject *iter; PyObject *item;

if (!PyArg_ParseTuple(args, “O”, &obj)) {

return NULL;

} if ((iter = PyObject_GetIter(obj)) == NULL) {

return NULL;

} while ((item = PyIter_Next(iter)) != NULL) {

/* Use item */ ... Py_DECREF(item);

}

Py_DECREF(iter); return Py_BuildValue(“”);

}

讨论¶

The code in this recipe mirrors similar code in Python. The PyObject_GetIter() call is the same as calling iter() to get an iterator. The PyIter_Next() function invokes the next method on the iterator returning the next item or NULL if there are no more items. Make sure you’re careful with memory management—Py_DECREF() needs to be called on both the produced items and the iterator object itself to avoid leaking memory.