Re: TRY_CATCH()

[Kris Warkentin <kewarken@qnx.com>]

Andrew Cagney wrote:

>PS: I recall this being proposed years ago, but the mechanism proposed 
>at the time had a more cumbersom syntax, from memory something like:
>
>   TRY_BEGIN
>     ... do stuff ...
>   TRY_END;
>  
>

I saw something similar to this that worked really well but was not 
quite as generic.  Basically you would have to add a 'TryStack' member 
to whatever data structure you were planning to capture exceptions on.  
The TryStack was a stack of jmp_bufs.  Then you'd do something like

if((error = TRY(mystruct)) == 0){
    do_stuff(mystruct);
    TRY_END(mystruct->try_stack);
}
else{
    CATCH(mystruct, error);
    handle_error();
}

The TRY would push a new jmp_buf onto the TryStack and the TRY_END and 
CATCH would pop one.  The various macros would be like #define TRY(foo) 
is try_push(foo->try_stack) and so on.  It's actually quite clever:  If 
something THROWs, it also pops but CATCH only pops if the error value is 
zero so that you can have multiple tries and catches on a single block.

Anyway, interesting stuff.

cheers,

Kris