[c++-pthreads] Re: pthread_cancel and EH: let's try this again

[Peter Dimov]

Wil Evers wrote:

> As the discussion on this list illustrates, mapping cancellation
> requests to exceptions is causing real headaches.

Mapping cancellation to an (ordinary C++) exception has been proven to work 
in practice. The primary source of real headaches is the discussion itself.

> In addition, and contrary to common usage of exceptions, a
> cancellation request is *not* an error in the sense that it
> immediately prevents the current thread from progressing any further.

A cancellation request is a request for a thread to not progress any 
further. It's pretty much a textbook example for using exceptions - a 
long-distance return all the way up, with the middle layers nearly never 
needing to not propagate it.