Re: [AD] 4.3 error handling

[Elias Pschernig <elias@xxxxxxxxxx>]

On Fri, 2006-06-09 at 18:12 +1000, Peter Wang wrote:
> On 2006-06-08, Chris <chris.kcat@xxxxxxxxxx> wrote:
> > On Wednesday 07 June 2006 23:52, Peter Wang wrote:
> > > They are completely independent in my example, e.g. API1 = graphics
> > > library, API2 = network library.  The _user_ is using both libraries,
> > > but neither library knows or cares about the other.
> > 
> > As they shouldn't. A graphics library wouldn't call network functions, and 
> > vice versa. I don't see what the problem is. The graphics library would jump 
> > to its catch on error, and the network lib would jump to its catch on error 
> > (just like using C++, the libs would/should throw an object of a type 
> > specific to their libraries).
> 
> You're right about this, sorry.  I only just checked my understanding of
> C++ exceptions now (after my exam).  I was thinking of `finally' in Java.
> 

The problem though lies at the user, who will use both - and we can't
rely on them knowing all the gotchas when using different libs with
different setjmp/longjmp implementations. For example:

int main(void)
{
    sfxlib_try {
        al_try {
            al_audio_init();
            sfxlib_init();
        }
        al_catch {
            printf("al_audio_init failed.\n");
        }
    }
    sfxlib_catch {
        printf("sfx_init failed.\n");
    }
}

The al_try {} block must not be left (with goto, return, break, or here
with longjmp) - so this will crash.

However, in C++, it would be perfectly valud to do this, so users simpy
*will* do it, no matter how big a warning we put into the docs.

-- 
Elias Pschernig