On Thu, May 13, 2021 at 7:44 PM Ethan Furman <[email protected]> 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
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