[duneroadrunner]

> I wrote a post about it.[1]

I just read it, and I thought it was great. I had a similar, if perhaps not-as-well-thought-out, reaction to Manish's (I agree, excellent) post. I think SaferCPlusPlus basically implements the permission mechanisms you listed in the summary (as well as the preceding "Race-Safe Strategies" post). (Although with some of the restrictions enforced at run-time rather than compile-time.) Looking forward to Cone 1.0. :)

p.s.: btw, the link on your post to the preceding "Race-Safe Strategies" post is broken

[jondgoodwin]

Did you also read the follow-on post on transitional permissions?

[duneroadrunner]

No, I just read it. SaferCPlusPlus does support all the permission "modes" listed, except the "opaque" one, and transitioning between them (though being stuck with C++'s move semantics). The permissions modes that aren't intrinsic to C++ are enforced at run-time. Objects to be mutably (non-atomically) shared need to be put in an "access control" wrapper, which is kind of like a generalized version of Rust's RefCell<> wrapper.

As I noted in my original comment, in the "mutex"/"RwLock" case, SaferCPlusPlus allows you to simultaneously hold read-locks and write-locks in the same thread. Which seems natural, since SaferCPlusPlus (and Cone) allows const and non-const pointer/references to coexist in the same thread. But in this case it actually provides increased functionality. It is the functional equivalent of replacing your mutex (and Rust's RwLock) with an "upgradable mutex", which facilitates better resource utilization in some cases, right? It also provides new opportunities to create deadlocks, so the mutex has to detect those.

Btw, I am certainly a pot talking to a kettle here, but your "mutex1" urgently needs a better name, right?