Ideally, (at least) trivial subclasses could be declared, and the class itself would serve as the marker. I would prefer regular subclasses, so that they could offer methods as well. Alternatively, at least copy the instance __dict__ to the new ExceptionGroup instance.
By compatible __init__ and __new__, I mean "whatever you do in ExceptionGroup.subgroup to create a new instance with fewer contained Exceptions ... do the same with MyExceptionGroup." I'm assuming that "whatever" is to call __new__ and __init__ with "a message string and a sequence of the nested exceptions, for example: ExceptionGroup('issues', [ValueError('bad value'), TypeError('bad type')])." -jJ _______________________________________________ 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/SFE46EGTGLXLCJDXZ4EI6HOEATYREOL4/ Code of Conduct: http://python.org/psf/codeofconduct/