Re: [boost] Boost and exceptions

Subject: Re: [boost] Boost and exceptions
From: Robert Ramey (ramey_at_[hidden])
Date: 2012-06-23 18:33:19

Dave Abrahams wrote:
> on Sat Jun 23 2012, "Robert Ramey" <ramey-AT-rrsd.com> wrote:
>
>> If you really like boost::exception your code when you eventually can
>> eventually rethrow
>>
>> catch (std::exception & e){ // not additon of &
>>     BOOST_THROW_EXCEPTION(e)
>> }
>
> IIUC, even if you change it to catch by reference, as you should, and
> even if std::exception weren't an abstract base class, which it is,
> that approach will slice the caught exception and lose all the
> information thrown with it.  BOOST_EXCEPTION_THROW_EXCEPTION needs to
> copy the exception object into this type it builds with multiple
> inheritance from boost::exception, and it needs to do this with full
> knowledge of the static type of the exception being thrown.

wow I overlooked this.

So in our case, if e was reference to an instance of a 
boost::archive::archive_exception object
which holds all the interesting data, this information would be thrown away 
along
with the actual type of the exception?  That's terrible.

Robert Ramey