[DGD] error context frames versus stack frames

[Raymond Jennings]

Just remember, function calls, catches, and rlimits can all nest separately.

Each function can itself have zero or more each of catch and rlimits
blocks nested pretty much arbitrarily.

catch {
   rlimits (50; 50000) {
      rlmits (20; 200) {
          catch(error("Foobar"));
          error("Baz");
      }
   }
}

Also, don't forget, that if you're in a catch handler (or anywhere
else for that matter) inside a tick limiting rlimits, and you are out
of ticks, you will immediately encounter a fresh "Out of ticks" error,
even in a catch handler.

On Thu, Apr 13, 2017 at 11:01 AM, Felix A. Croes <felix at dworkin.nl> wrote:
> Carter Cheng <cartercheng at gmail.com> wrote:
>
>> Is this basically used to locate the correct exception frame on the stack
>> corresponding to the function activation? In something like C++ one has to
>> unwind until one reaches a handler if it exists. I suspect in dgd's version
>> of lpc one has two unwind until one gets to the "function activation" that
>> originates the catch/rlimit blocks the resume execution after the
>> catch/rlimit
>
> Yes, there is an exception stack and a rlimits stack, both independent
> of the function stack.  When handling an exception DGD actually takes
> the exception stack as its lead, and unwinds function calls and rlimits
> contexts as needed.
>
> Regards,
> Felix Croes
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