Negative

[Walter Bright]

"Sean Kelly" <sean at f4.ca> wrote in message 
news:du25eb$288m$3 at digitaldaemon.com...
> Not in the above example, but then the above example doesn't even compile. 
> I assumed you were talking about something like this:
>
> Foo f;
> Bar b;
> try {
>     f = dofoo();
>     b = dobar();
> } catch( Object o ) {
>     delete f; delete b;
> }
>
> It's quite possible for f and b to both be uninitialized, yet I would 
> expect the delete calls to be well-defined anyway.

delete is well defined, and works properly with null. For more complex 
unwinding, you'll need to add state variables to keep track of what has been 
set and what hasn't.

The new bug in the above code is that the catch block fails to rethrow o.

I hope that these buggy examples show just how hard it is to get 
try-catch-finally to be correct, and how easy it is to get the on_scope 
correct. This leads me to believe that try-catch-finally is just 
conceptually wrong, as it does not match up with how we think despite being 
in common use for over a decade.