Documentation for PyObject_GetItem and PyObject_SetItem here states:
PyObject* PyObject_GetItem(PyObject *o, PyObject *key) Return value: New reference.
Return element of o corresponding to the object key or NULL on failure. This is the equivalent of the Python expression o[key].int PyObject_SetItem(PyObject *o, PyObject *key, PyObject *v)
Map the object key to the value v. Returns -1 on failure. This is the equivalent of the Python statement o[key] = v.
foo[key] syntax implies PyType_Dict
However, it doesn't state whether it also works on PyType_List, in which case key would be an index, i.e. a positive PyType_Long, or maybe a type converts into it, e.g. a PyType_Bytes containing "42".
Does this function work for both containers?
I would expect it to; such a design to be in keeping with Python's "it does everything you would expect it to do" philosophy.
Furthermore, the project I'm looking at has a comment forewarning:
// PyObject_SetItem is too weird to be using from C++
// so it is intentionally omitted.
Should I be worried about this? What could it possibly mean? And has it been fixed for Python3?
Both functions work for all containers that support indexed accesses, be they dict, list, tuple, string, bytes, and so on.
I'm not sure why PyCXX has that comment; it may be due to the fact that Python's dynamic typing does not always mesh well with languages with static typing.