Re: [boost] [exception]throw_exceptions concerns

Subject: Re: [boost] [exception]throw_exceptions concerns
From: Gennadiy Rozental (rogeeff_at_[hidden])
Date: 2009-01-03 20:43:05

Emil Dotchevski <emildotchevski <at> gmail.com> writes:

> 
> On Fri, Jan 2, 2009 at 5:19 AM, Gennadiy Rozental
> > 1. What does the first one means and should we worry?
> 
> You shouldn't worry, it means that you can't catch a bad_weak_ptr
> exception as exception_detail::clone_impl<bad_weak_ptr>, which is by
> design.

Can you please elaborate? If I use 

boost::throw_exception( my_exception() );

How do I catch it?

> > 2. Does the second means that std::exception is not copy constructible? If
> > yes can we disable it inside the header?
> 
> I suppose you mean boost::exception, not std::exception.

Right. An error message was referring to the 'exception'. I guessed wrong what
it means.
 
> Boost::exception is copy constructable but its copy constructor is
> protected to prevent the user from accidentally slicing the exception
> object using a catch(boost::exception e) instead of the correct
> catch(boost::exception & e).

Fine. But both exceptions have to be disabled in a header (especially since it's
now compiled pretty much always)
 
> >  a) Was it agreed that practically all Boost users are now exposed to the
> > Boost.Exceptions library by default whether they are willing or not
> 
> There was rather lack of interest in discussion before this change in
> throw_exception was implemented, but there was a later discussion
> which lead to refactoring of the throw_exception hook.

Can you please point me?
 
> "Exposed to" is technically correct, but that exposure is limited to
> "boost/exception/exception.hpp", which does not include any headers
> and was carefully designed for the purpose of the throw_exception
> integration.

It adds <typeinfo>, which may be serious, since shared_ptr takes special care to
work around the case when typeinfo is not supported by underlying system.
 
> >  b) throw_exception documentation is now incorrect and misleading, since it
> > does not mention this
> 
> I consider throw_exception part of Boost Exception and so it's documented here:
> 
> http://www.boost.org/doc/libs/1_37_0/libs/exception/doc/throw_exception.html
> 
> The previous separate documentation should be removed.

Remove it than. As of now incorrect one is the first found by google.
 
Gennadiy