Andrew Barnert wrote: > On Oct 14, 2019, at 13:28, Steve Jorgensen [email protected] wrote: > > Andrew Barnert wrote: > > On Oct > > 14, 2019, at 07:15, Steven D'Aprano [email protected] wrote: > > Speaking of UserString, does anyone know why it isn't > > registered as a > > virtual subclass of str? > > None of the concrete classes register virtual subclasses, so this would be a > > unique exception. > > See the final lines in > > https://github.com/python/cpython/blob/3.7/Lib/_collections_abc.py > > MutableSequence.register(list) > > MutableSequence.register(bytearray) # Multiply inheriting, see > > ByteString > > But that’s the exact opposite: it registers list and bytearray as virtual > subclasses of the ABC MutableSequence, it doesn’t register MutableSequence as > a virtual > subclass of the concrete classes list and bytearray. Doing the latter would > not only (like > Steven’s proposal) be unprecedented and require changes to builtin types, but > also > (completely unlike Steven’s proposal) be just wrong—it’s certainly not true > in any useful > sense that every mutable sequence is usable as a bytearray.
Ah! Yes. I hadn't read carefully enough. _______________________________________________ Python-ideas mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/[email protected]/message/BOCOGNYY4YRIDQAWXMOQQZGGQCTHRQUE/ Code of Conduct: http://python.org/psf/codeofconduct/
