On Mon, May 24, 2021 at 11:44 AM Tal Einat <talei...@gmail.com> wrote: > > But frankly Luciano's idea of a base class that can be subclassed seems the > > most startightford to me. > > Yes, and it's what I originally suggested near the beginning of this thread :)
I am sorry to have missed your previous e-mail with a base class for sentinels, @Tal. I support that idea. In fact, if we have a SentinelMeta metaclass, and a Sentinel base class built from SentinelMeta, the Sentinel class can be used directly as a sentinel without the need for subclassing—if the application does not require a custom sentinel. If it does, then the user can subclass Sentinel. The SentinelMeta could be private, to discourage misuse. This is my implementation, after learning from @Tal's code: https://github.com/fluentpython/example-code-2e/blob/master/25-class-metaprog/sentinel/sentinel.py Since having a Sentinel base class is desirable for ease of use, I think it is simpler to code the __new__ method in it, instead of coding metaclass logic to inject __new__ in the class namespace. Best, Luciano -- Luciano Ramalho | Author of Fluent Python (O'Reilly, 2015) | http://shop.oreilly.com/product/0636920032519.do | Technical Principal at ThoughtWorks | Twitter: @ramalhoorg _______________________________________________ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-le...@python.org https://mail.python.org/mailman3/lists/python-dev.python.org/ Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/UUXUKG3UZLTWKXPV6IZAE5KOMEJHMUS5/ Code of Conduct: http://python.org/psf/codeofconduct/
