I’m not sure how much of SC is driven by C++ properties and how much by Smalltalk, but when I read about coroutines I think about channels to communicate between them. So one Routine listens on a channel, the other sends a message, like ‘I’m done’; ‘here is a error’; ‘no error’; ‘got some data for you’:
It’s a different way of thinking. Erlang and Go seems to handle this well, for Smalltalk it seems to be harder to find good information about it though.