🚀 go-pugleaf

On Monday, April 15, 1996, Bob Friesenhahn wrote...
> Kevin Cline wrote:
> 
> > Can someone on the committee indicate whether it was the committee's
> > intention for the standard exception class hierarchy to be used in
> > general C++ programming, or whether the intention was for the standard
> > exception class hierarchy to be reserved to the Standard C++ library?
> > 
> > Another developer on our team has asked
> >   How can we be sure that ANSI C++ library callbacks work
> >   correctly in the face of exceptions?  What if ANSI C++
> >   library code catches *our* exception?
> 
> A further consideration is that often it is valuable to know what
> body of code generated an exception.  If all exeptions are derived
> from the same base class, then it will be impossible to tell if
> an exception occurred in standard library code, user code, or some
> third party library. An additional level of derivation could be
> used to satisfy this requirement, but since the standard exception
> classes have already been defined, there is no satisfactory place
> to insert the additional derivation.
> 
> By using a different base class for each seperately maintained body
> of code, it will be possible to provide handlers for each code body
> with the additional maintenance expense of maintaining the additional
> catch blocks.
> 
> Bob

I don't see this as a real problem (determining if the user's code
generated the exception). Consider this:

class user_defined_exception: virtual public exception { ... };
class user_logic_error: virtual public logic_error, virtual public
user_definded_exception { ... };

... catch (logic_error* e)
{
	if (dynamic_cast<user_defined_exception>(e)) ...
}

This will tell you if the logic error you caught was one defined in your
own code or somebody else's.




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