Updated ARM Spec

[David Holmes]

Paul Benedict said the following on 10/27/10 09:49:
> I may have read Joe's email wrong, but I thought he wanted the ability
> to tell certain Throwable instances not to tag on additional data. I
> thought he wanted to have immutability when he needed it. So why can't
> you preallocate your Throwable instances, call freeze(), and share
> them? What is "null" doing that freeze() cannot?

I agree this is feasible. If internally we use "null" to represent 
immutability then freeze() could set everything to null, and the VM 
allocated instances would act as-if they were constructed and then had 
freeze() invoked upon them.

The only downside to freeze() is that it freezes everything at once 
whereas the current scheme allows you to make the stacktrace immutable 
independently of the suppressedExceptions, and independently of the 
cause (which is a set once property anyway). The VM may make instances 
that are fully immutable, but the user may want more flexibility here.

Cheers,
David