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Re: Try/Catch Exception Objects: Possible?

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Leon Timmermans
July 26, 2013 11:00
Re: Try/Catch Exception Objects: Possible?
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On Fri, Jul 26, 2013 at 9:52 AM, Kent Fredric <> 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
> 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 )




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