>>> It's storing borrowed references, so it'll work as long as something
>>> else in Python-space keeps it alive (which is, as evidenced, a rather
>>> precarious situation to be in).

>> Indeed. I'm confused, though: in the example I've given, all 4 nodes
>> have references not only to each other but in the method scope of
>> test_dfs. It's unclear to me how or why they'd be garbage collected
>> (or decref'd to 0) before test_dfs() finished (since it's a call in
>> the last line of test_dfs where the crash takes place).

> If you want to do this, write an auto_ptr-like class, a class
> overloading operator* and operator->, let's call it pyptr, which has a
> PyObject* member but does INCREF on construction and DECREF on destruction.

> Then simply create std::vector<pyptr> rather than std::vector<PyObject*>.

> This *should* work, but to my knowledge there isn't any code available
> already, so please report back if you do this and perhaps we can include
> the pyptr class with Cython.