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Postings from July 2013
On Fri, Jul 26, 2013 at 9:52 AM, Kent Fredric <kentfredric@gmail.com> wrote:
>> That's almost intentionally pathological, though. And the failure of
>> existing stacktrace tools on exception objects is an existing problem
>> in those modules irrespective of a change in core.
>
> Indeed, however, I figure being able to get back traces out of things
> is reasonably important, so whatever we do, that should be one of the
> things we (at least eventaully) solve.
>
>> Like what? caller() and constructing a proper message that matches the form?
>
> My memory is that this is somewhat a problem, because this means you
> have to walk the whole stack and take a snapshot of the stack,
> iterating calls to caller(), for which the respectful code in even
> Carp.pm is a rather nasty rabbit warren.
>
> And my memory of seeing this in Object implementations is that
> creating a stack array is a little bit expensive if the exception is
> just going to be flow control, and the stack trace will never be
> needed.
>
> Thats the real perk of Carp::Always and Devel::SimpleTrace, you don't
> have to pay for that if you're not using it.
>
> Now, if there could be some lazy way to reference a point in Perl
> time/code/memory at the time an exception was thrown, that made it
> possible to introspect the stack that occurred at that time, in an
> efficient manner, that'd be cool.
That sounds a bit like Yuval's Devel::StackTrace::XS [1]
> I'd be especially cool, because it wouldn't inherently bind you to
> having one type of stack trace presentation, and one type of stack
> trace presentation only, things like Carp::Always could hook in to
> this facility, ie:
>
> if ( $_->isa('exceptionything') ) {
> my $stack = CORE::stacktracefor($_);
> print $_->message . custom_stacktrace_formatter($stack);
> }
>
> ( The point being its useful to be able to decouple the presentation
> logic from the actual exception implementation so that presentation
> can be changed at the top level when needed )
Agreed
Leon
1: https://github.com/nothingmuch/Devel-StackTrace-XS/
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