Re: [boost] Do we need a boost_exception class or idiom?

From: Fernando Cacciola (fernando_cacciola_at_[hidden])
Date: 2002-11-20 17:31:45

----- Original Message -----
From: "David Abrahams" <dave_at_[hidden]>
To: "Boost mailing list" <boost_at_[hidden]>
Sent: Wednesday, November 20, 2002 6:40 PM
Subject: Re: [boost] Do we need a boost_exception class or idiom?

> "Fernando Cacciola" <fernando_cacciola_at_[hidden]> writes:
>
> > I'm not sure if a boost exception class is *needed*, but I see no
problem in
> > having one.
> > Anyway, IIF such an exception class is defined, I *strongly* encourage
(as I
> > did in the past) that it provides:
> >
> >   virtual void raise() const
> >   {
> >     #ifndef BOOST_NO_EXCEPTIONS
> >       throw *this ;
> >     #endif
> >   }
> >
> > and that boost libraries throw such exceptions *only* by calling
.raise():
> > i.e. never with a throw expression directly in the user code.
>
> 1. Why should this be a virtual function? The dynamic type of an
>    exception object is never used in a throw expression.
>
Just to avoid visivility issues with redefinitions in derived types (to
avoid the compiler telling that 'raise' hides definition on the base class)

> 2. Why are we reinventing the wheel?  What's wrong with
>    boost::throw_exception() from boost/throw_exception.hpp?
>
Nothing :-)
I like this approach... and I had forgot about it.
Anyway, I was just pointing out that IIF a boost exception class was defined
it should throw itself.

Fernando Cacciola