On Fri, Sep 4, 2015 at 8:05 AM, Ludovic Courtès <l...@gnu.org> wrote: > "Thompson, David" <dthomps...@worcester.edu> skribis: > >> Now, I think this solves the immediate need of being able to live hack >> dmd, but I'd like to note an additional shortcoming: Thread >> synchronization isssues. As you know, there's potential for the main >> dmd thread and a REPL thread to write to the same memory and blow >> things up. In practice, this would be unlikely, but it shouldn't even >> be a possibility. To accommodate programs that run in an event loop >> (though I know dmd doesn't truly have this yet), Mark and I developed >> the (system repl coop-server) module available in Guile 2.0.11. This >> "cooperative" REPL server can be integrated into an event loop and >> guarantee that expressions are only evaluated in the context of a >> single thread, in this case the main thread. I think that this should >> be the approach taken in the not-so-long term, which will require >> modifying dmd itself. > > I agree that the cooperative REPL server is the way to go. I just > couldn’t resist the temptation to hack that thing. ;-) > > It would be ideal if instead of having built-in support for the REPL > server, dmd instead provided a way for services to return file > descriptors to monitor and if they could be notified of I/O events on > those file descriptors. That way, the REPL server could be a normal > REPL service.
That sounds like a nice generalization. >> Now that we can live hack dmd, we'll need some things to help make it >> pleasant. Most of the time I am tweaking service definitions until >> they are just right. Currently, that means calling a procedure to >> unload the version that exists, and then registering a new one. I'd >> like to reduce that to a single step to tighten the feedback loop. >> What do you think about adding a 'register-services*' procedure, or >> maybe a 'define-service' form, that first unregisters the old service >> before registering the new one? > > Sounds good to me. Okay, I will prepare some patches. Thanks. - Dave
