The docs for the __init_subclass__ hook (see PEP-0487 for background) give this example: class Philosopher: def __init_subclass__(cls, /, default_name, **kwargs): super().__init_subclass__(**kwargs) cls.default_name = default_name class AustralianPhilosopher(Philosopher, default_name="Bruce"): pass The / in the method signature threw me for a loop (difficult to search for secondary uses of operators) but I finally ran across the concept of positional-only parameters. Why is it used here, in __init_subclass__? Does this mean that all class methods with cls or self as initial arguments should be using /? I thought Python had a "we're-all-adults-here" philosophy where class designers don't have to be bulletproof against malicious use. Continue reading...
