boost.threads [was RE: [boost] Re: sockets /network programming Requirements]

From: williamkempf_at_[hidden]
Date: 2001-08-03 14:52:09

--- In boost_at_y..., williamkempf_at_h... wrote:
> --- In boost_at_y..., "Alexander Terekhov" <terekhov_at_d...> wrote:
> > but then his code would never call thread::exit so there
> > will be no problems. also, IMHO catch(...) without "throw;"
> > or program termination is inherently flawed (e.g. who is
> > supposed to delete the object thrown by not so smart pointer,
> > etc) so i do not see any good reasons not to provide
> > exception based thread::exit even w/o catch(...)
> > workarounds.
> 
> Did you totally miss the point about LogError()?  *ANY* processing 
> done within the catch(...) block is probably not wanted when the 
> exception is of type boost_thread_exit_dont_catch_me().  Using 
> exceptions is only going to lead to what is viewed as bugs, and 
bugs 
> that can't be worked around.  I won't use such a system, and I'll 
bet 
> most others won't as well.

In case I've not convinced you yet, here are two other core language 
issues with this approach.

1) If while processing an exception a local is destroyed whose 
destructor throws an exception, terminate will be called. (15.2/3)

2) Consider the following: void foo() throw() { bar(); }.

What's needed is exception style stack unwinding with no possiblity 
of the user circumventing things.  To truly get this in a portable 
manner that covers all the bases is likely going to require a core 
language change and compiler support.  This is precisely one of the 
reasons why we need a "designed from the ground up" C++ solution 
instead of a simple wrapper around POSIX or Win32 threads.  We're 
doing the best we can to give a library implementation of such a 
design, which hopefully can be used for some today, noting any holes 
that exist because of changes needed to the C++ abstract machine.  If 
a concept (like this one) can't be done in the library, we're 
removing it with the hopes that it can be added again if/when it's 
adopted into the language standard.

Bill Kempf