Introduce SafePyObject, make TorchDispatchTypeObject use it
The pattern of a PyObject* bundled with a PyInterpreter* is pretty
useful in many contexts (e.g., TorchDispatchTypeObject) so I have turned
it into a dedicated class SafePyObject. In the process I fixed a
bug with the old TorchDispatchTypeObject (copy constructor/assignment
was not deleted), made the API more safe (retrieving the PyObject*
pointer requires verification that the PyInterpreter* matches) and
fixed some minor inefficiencies in C++ code.
Signed-off-by: Edward Z. Yang <ezyangfb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/75142
Approved by: https://github.com/zou3519
