Re: [Vala] Questions on async functions

[Nor Jaidi Tuah <norjaidi tuah ubd edu bn>]

> I haven't actually used async's, so I'm not sure of the specifics, but
> I've used that structure to simulate pretty much exactly what you're
> suggesting.  In my case, each "async function" had an initialiser that
> built and queued a structure with all the required variables, plus one
> which was plugged into a switch/case statement containing the
> individual segments of code, and updated to advance onto the next one
> on the next resume.  Yielding from within a loop got a little
> interesting, and it was a pain to follow at times, but it worked.
> Same pattern should work for you.

I'd done this sort of gymnastics before, "yielding" from
a function containing a loop containing a recursive call,
saving the "continuation" to a file, and able to resume when
the application is restarted. But I prefer readable code
rather than self torture. The async function is a great
feature, allowing long-running computation to yield without
having to obscure the logic with book-keeping matter. I hope 
vala will evolve further into a language where a continuation 
is a fully accessible object. It would be great if we can do 
something like these:

  x = async_function.begin ()  // get a handle to the continuation

  save_to_file (x);  // useful for very very long computation

  read_from_file (out x);
  x.resume ();      // resume our very very long computation

  x.cancel ();  // a feature that answers my original query!

hand
Nor Jaidi Tuah