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Re: my $@ - a proposal

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On 6/27/08, Graham Barr <gbarr@pobox.com> wrote:
>  I think this is the only sane way to preserve the fact that DESTROY can
> throw errors, but fix the issue that it can clear $@
>
>  The same could be considered for any implicitly called sub, overloading,
> tied etc...
>
>  Graham.
so do we want a pair of macros then, SAVE_PRECIOUS and
RESTORE_PRECIOUS, instead of just
$ diff -wu pristine_perl-5.8.8/sv.c perl-5.8.8/sv.c
--- pristine_perl-5.8.8/sv.c    2006-01-16 06:22:21.000000000 -0600
+++ perl-5.8.8/sv.c     2008-06-27 12:52:05.253802600 -0500
@@ -5164,6 +5164,7 @@
                stash = SvSTASH(sv);
                destructor = StashHANDLER(stash,DESTROY);
                if (destructor) {
+                   SV* orig_error = newSVsv( ERRSV ); /* make local
copy of $@ */
                    SV* const tmpref = newRV(sv);
                    SvREADONLY_on(tmpref);   /* DESTROY() could be naughty */
                    ENTER;
@@ -5185,6 +5186,15 @@
                        SvROK_off(tmpref);
                    }
                    SvREFCNT_dec(tmpref);
+                   if(SvTRUE(orig_error)){
+                       if (!SvTRUE(ERRSV)){
+                        /* restore $@ from local copy if $@ got cleared */
+                            sv_setsv(ERRSV, orig_error)
+                       }else{
+                       /* presume that PROPAGATE worked correctly and
do nothing */
+                       }
+                   }
+                   SvREFCNT_dec(orig_error);
                }
            } while (SvOBJECT(sv) && SvSTASH(sv) != stash);
It might be better do localize *@ instead of $@ but I don't know how to do that;
some kind of logic to propagate ERRSV to orig_error would make sense,
and could possibly replace the propagate (or also use -- it could
become its own function or macro) logic in pp_die.

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• my $@ - a proposal by Yuval Kogman
• RE: my $@ - a proposal by Jan Dubois
• Re: my $@ - a proposal by David Nicol
• Re: my $@ - a proposal by Graham Barr
• Re: my $@ - a proposal by David Nicol
• Re: my $@ - a proposal by Mark Mielke
• RE: my $@ - a proposal by Jan Dubois
• Re: my $@ - a proposal by Graham Barr
• Re: my $@ - a proposal by Graham Barr
• RE: my $@ - a proposal by Jan Dubois
• Re: my $@ - a proposal by Ben Morrow
• Re: my $@ - a proposal by Graham Barr
• RE: my $@ - a proposal by Jan Dubois
• Re: my $@ - a proposal by David Nicol
• RE: my $@ - a proposal by Jan Dubois
• Re: my $@ - a proposal by David Nicol
• RE: my $@ - a proposal by Jan Dubois
• Re: my $@ - a proposal by David Golden
• Re: my $@ - a proposal by Johan Vromans
• Re: my $@ - a proposal by Mark Mielke
• Re: my $@ - a proposal by Rafael Garcia-Suarez
• Re: my $@ - a proposal by Mark Mielke
• Re: my $@ - a proposal by Ben Morrow
• Re: my $@ - a proposal by Elliot Shank
• Re: my $@ - a proposal by Abigail
• Re: my $@ - a proposal by Juerd Waalboer
• Re: my $@ - a proposal by David Golden
• Re: my $@ - a proposal by Yuval Kogman
• Re: my $@ - a proposal by David Golden
• Re: my $@ - a proposal by Graham Barr
• Re: my $@ - a proposal by Yuval Kogman
• Re: my $@ - a proposal by Graham Barr
• Re: my $@ - a proposal by Sam Vilain
• Re: my $@ - a proposal by David Nicol
• Re: my $@ - a proposal by David Golden
• Re: my $@ - a proposal by Graham Barr
• Re: my $@ - a proposal by David Nicol
• RE: my $@ - a proposal by Jan Dubois
• Re: my $@ - a proposal by Aristotle Pagaltzis
• Re: my $@ - a proposal by Mark Mielke
• Re: my $@ - a proposal by Raphael_Manfredi
• Re: my $@ - a proposal by Mark Mielke
• Re: my $@ - a proposal by Raphael_Manfredi
• Re: my $@ - a proposal by Abigail
• Re: my $@ - a proposal by Mark Mielke
• Re: my $@ - a proposal by David Golden
• Re: my $@ - a proposal by Raphael_Manfredi
• Re: my $@ - a proposal by Dr.Ruud
• Re: my $@ - a proposal by Yuval Kogman
• Re: my $@ - a proposal by Sam Vilain
• Re: my $@ - a proposal by Abigail
• Re: my $@ - a proposal by Yuval Kogman
• Re: my $@ - a proposal by Sean O'Rourke
• Re: my $@ - a proposal by Yuval Kogman
• Re: my $@ - a proposal by Steffen Mueller
• Re: my $@ - a proposal by Yuval Kogman
• Re: my $@ - a proposal by David Golden
• Re: my $@ - a proposal by Yuval Kogman
• Re: my $@ - a proposal by David Golden
• Re: my $@ - a proposal by Abigail
• Re: my $@ - a proposal by Aristotle Pagaltzis
• Re: my $@ - a proposal by Mark Mielke
• Re: my $@ - a proposal by Yuval Kogman
• Re: my $@ - a proposal by Dr.Ruud
• Re: my $@ - a proposal by Mark Mielke
• Re: my $@ - a proposal by Sam Vilain
• Re: my $@ - a proposal by David Cantrell
• Re: my $@ - a proposal by Sam Vilain
• Re: my $@ - a proposal by Moritz Lenz
• Re: my $@ - a proposal by Sam Vilain
• Re: my $@ - a proposal by Moritz Lenz
• Re: my $@ - a proposal by Sam Vilain
• Re: my $@ - a proposal by Moritz Lenz
• Re: my $@ - a proposal by Sam Vilain
• Re: my $@ - a proposal by Abigail
• Re: my $@ - a proposal by Mark Mielke
• Re: my $@ - a proposal by Aristotle Pagaltzis
• Re: my $@ - a proposal by David Nicol
• Re: my $@ - a proposal by Nicholas Clark
• Re: my $@ - a proposal by David Nicol
• RE: my $@ - a proposal by Jan Dubois
• Re: my $@ - a proposal by David Nicol
• Re: my $@ - a proposal by Reini Urban
• Re: my $@ - a proposal by Dr.Ruud
• Re: my $@ - a proposal by Sam Vilain