On 9 August 2013 12:35, William ML Leslie <[email protected]> wrote:
> On 9 August 2013 11:48, Jonathan S. Shapiro <[email protected]> wrote:
>> That's to strong. First, the backtrace printing mechanism isn't done in a
>> handler. It's done deep in the runtime. Second, it's perfectly fine for
>> unwind code to change the stack pointer. All we need to do to support the
>> backtrace is to save the stack pointer that was current at the time of the
>> most recent exception on that thread.
>
> That doesn't seem sufficient, because all of the stack above the frame
> of the handler can be overwritten by the handler. A pointer into
> space that is available for allocation is not useful.
I guess that if you really want the traceback, we could make you
declare your intent in the handler.
try:
party_time()
# Extended except form declares that it wants a traceback,
# which will be generated if not provided.
# not saying anything about who can create values of type
# TraceBack.
except (e : OutOfBeer, tb : TraceBack):
logger.exception("Party ran dry", tb)
# extended raise form means no traceback needs to be
# generated if the next handler wants one
# not sure if I want the caller to be able to lie, but oh well
raise e, tb
--
William Leslie
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