This [the potential integration with throw_exception] is proving to be a distraction from the Stacktrace review and I think that we need to postpone this discussion for when Stacktrace is accepted.
Although, on second thought, there is one pertinent question that seems to have come up. Specifically, if the library should be extended to allow me to capture the trace on my own using RtlCaptureStackBackTrace or ::backtrace, then at some later point use the rest of the Stacktrace functionality. And additionally, can I do that for ::backtrace captures even when Stacktrace is using a different backend (unwind) as its default.
From a quick look at the code, it seems that the library cannot currently use more than one backend at the same time because they are all named 'class backend'.
As a note, the documentation states that backtrace is a POSIX function, but it seems to be Linux-specific. I can't find it in the POSIX standard. I doubt that unwind is also standard POSIX. Does the library support OS X?