On 15/11/2018 12:29, Emil Dotchevski wrote:
It uses thread_local raw pointers, one per error type. This is needed in order to decouple result<T> from the static type of error objects being propagated, which I consider critical, see https://zajo.github.io/leaf/#rationale.
Is it compatible with coroutines or fibers or other non-thread-based stacks?
Good question. I'm not sure, but I'm interested to know what are the issues.
In general AFAIK, any use of thread-local storage is entirely incompatible with coroutines or fibers. (Unless the mechanisms for both cooperate with each other, which is theoretically possible but I'm not aware of it occurring in the wild.) (If you can guarantee that a given set of coroutines or fibers always executes within a single thread, then accessing thread-local objects created *outside* the coroutines is "safe" (they all access the same object, but non-concurrently; it can still lead to surprises if the object is mutable, however), but less so those created inside. Either way it's a little confusing.)