Re: [boost] Boost and exceptions

Subject: Re: [boost] Boost and exceptions
From: Emil Dotchevski (emildotchevski_at_[hidden])
Date: 2012-06-24 19:14:10

On Sat, Jun 23, 2012 at 10:40 PM, Robert Ramey <ramey_at_[hidden]> wrote:

> If this is invoked at the exception site it works.  If it is invoked
> anywhere else - like a rethrow it doesn't.  It's totally non-intuitive
> and a trap for users.  There is no mention of this in the documentation.
>

The danger of slicing in C++ is beyond the scope of any Boost library
documentation. That said, Boost Exception does protect the user from
slicing boost::exception objects.

> And I believe that a solution could have been crafted to avoid the issues
> that I've raised but that Emil doesn't agree that these concerns are
> legimate.  I know steve doesn't agree with me on this either.
>

The concerns are legitimate, the disagreement is over the conclusion you've
reached. You're yet to back your beliefs with facts.

> So now I would have to provide a counter example which means
> basically re-doing the original work in the right way as I see it.
>

A lot of time got wasted in this discussion explaining why your ideas don't
work. Producing a working piece of code would be a welcome change, I think.

> > I may be
> > misunderstanding, but IIUC, the "problem" that he "fixed" was that his
> > change caused already-unsupported misuses of boost::throw_exception to
> > stop compiling.  It's arguable that those misuses *should* be flagged
> > with compiler errors.
>
> the original boost::throw_exception was defined as:
>
> #ifdef BOOST_NO_EXCEPTIONS
> void throw_exception( std::exception const & e ); // user defined
> #else
> template<class E>
> void throw_exception(E const & e){
>    throw(e);
> }
> #endif
>
> it's hard to see how one could even define "misuse" of this - much
> less detect it.
>

You should try to see it though. Several people have pointed it out.

Emil Dotchevski
Reverge Studios, Inc.
http://www.revergestudios.com/reblog/index.php?n=ReCode