Re: On the case for exception-based error handling.

[Tony Olekshy]

Oops, accidentally sent message.  Here's the final version.

Chaim Frenkel wrote:
>
> Actually, why not simply unwind the call stack to the routine that
> has the pragma active.
>
>         sub foo {use exception; &baz()}
>
>         sub baz { throw "a fit" }
>
>         sub bar {
>                 no exception;
>                 &foo();
>         }

I don't think that will work.  Some routines on the way may expect
to get a chance at $err_code to do their cleanups, and now they're
toast.

> The unwind logic would treat a scope with no exception set _as if_
> each call were wrapped in at try block.

I don't think so.  If no exception is in scope Perl should continue
to generate and propagate exceptions (die and $@) as it does now,
so we don't break tradition.

> Fatal checking, is for core functions. And optional for module
> authors.

Yes.

> Then Fatal.pm and exception.pm could possibly be consolidated.

Yes.

Especially if we do that auto-fatal under try thing some others
have written about.  I have think about that some more before I
can try to say something intelligent, though.  That would imply
dynamic scope for use fatal, and I think it should probably have
lexical scope.

Yours, &c, Tony Olekshy