In short: in recent Pythons, impossible, by design. This is probably a good thing.
In Python ≤ 3.6, as discussed on stupidpythonideas, there was PyFrame_LocalsToFast in the CPython C API, which could be accessed via ctypes. This no longer works in 3.7 and later (PEP 558).
The alternative of using inspect.stack() and mutating the f_locals attribute of the frame object doesn't work, either.
See also Everything in Python is mutable.
(This issue is intentionally left open to collect links to related reading.)
In short: in recent Pythons, impossible, by design. This is probably a good thing.
In Python ≤ 3.6, as discussed on stupidpythonideas, there was
PyFrame_LocalsToFastin the CPython C API, which could be accessed viactypes. This no longer works in 3.7 and later (PEP 558).The alternative of using
inspect.stack()and mutating thef_localsattribute of the frame object doesn't work, either.See also Everything in Python is mutable.
(This issue is intentionally left open to collect links to related reading.)