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On Thu, May 13, 2021 at 7:44 PM Ethan Furman <ethan@stoneleaf.us> wrote:
Consider me complaining. ;-)
+1
An actual Sentinel class would be helpful:
>>> class Sentinel: ... def __init__(self, repr): ... self.repr = repr ... def __repr__(self): ... return self.repr ...
>>> MISSING = Sentinel('MISSING') >>> MISSING MISSING
>>> implicit = Sentinel('<implicit>') >>> implicit <implicit>
Here is my suggestion (also posted on the related bpo-44123), which is also simple, ensures a single instance is used, even considering multi-threading and pickling, and has a better repr: class Sentinel: def __new__(cls, *args, **kwargs): raise TypeError(f'{cls.__qualname__} cannot be instantiated') class MISSING(Sentinel): pass - Tal