Re: [Vala] Thoughts on asynchronous methods

On Sun, Sep 13, 2009 at 17:40:33 +0200, Jürg Billeter wrote:
This should be `yield return i;'. We do not use/need `yield return' for
async methods, and I'm planning to add support for `yield return' for
generators in Vala the same way as it's used in C#. I don't see a
conflict here.

Ok. You are right. It's a bit ugly syntax from C# but that does not matter.

This has nothing to do with asynchronous at all.

I understand this is would be complicated to implement, but please at least
don't use any of that syntax in an incompatible way.

Virtual machines actually have it pretty easy to implement. They just stash
away the running function state and than resume it. Vala can't easily do
that, but I see two options for it:

 - Generate the function in a special way so it is restartable. This would
   mean to generate an anonymous class. All arguments and variables would be
   converted to members of that class. Plus one extra member would remember
   which point the function last returned at. Than if the function contained
   no block-local variables, it should be possible to wrap it in a big case
   (similar to what Duff's device uses) to jump to the correct point to

That's roughly what we already do for async methods, and the
implementation will be very similar for generators.

I see now. Nice, indeed.

                                                 Jan 'Bulb' Hudec <bulb ucw cz>

[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]