Boldra has asked for the wisdom of the Perl Monks concerning the following question:

In perl5.10 the behaviour of a die handler is inconsistent: 

$SIG{__DIE__} = sub { print "\$@='$@'\n"; $@='' };

eval {die "string" };
print "\$@='$@'\n";

eval {die { } };
print "\$@='$@'\n";

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If the die gets passed a string, the signal handler has a local $@ which is empty, and modifying it doesn't affect the caller. If it gets passed a hashref, it doesn't localize it, and modifying it (calling eval inside sigdie) changes it in the caller's scope.

I know it was fixed by 5.18. I've tried finding it in perldelta, but I think I'm searching for the wrong thing. Does anyone know which Perl version this was fixed in? Thanks.

edit: missing semicolon



- Boldra

Replies are listed 'Best First'.
Re: When was $@ scope in sigdie fixed?
by Apero (Scribe) on Dec 07, 2015 at 11:56 UTC

    Version 5.14 is the exact value you're looking for, per the changelog notes at Exception Handling. This version can be enforced in code where this is a mandatory requirement with the stanza: 

    require v5.014_000;

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    .. which will cause code to die when that stanza is hit (or substitute use for require to make that a compile-time check, although IIRC that also enables some optional features as of that version by default as well.)

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        You're right that the first of your suggested forms is the recommended method for maximum comparability.

        Incidentally, any of those 3 forms work counting mine, at least in reasonably-recent Perl versions (though I'm not exactly sure how old would break with that.) I had intended for the form that dropped the leading v as the documentation says it's more backwards-compatible, but there it is.

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Re: When was $@ scope in sigdie fixed?
by choroba (Cardinal) on Dec 07, 2015 at 11:59 UTC
    I'm not sure, but maybe perl5140delta, see Exception Handling. 
    ($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

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Re: When was $@ scope in sigdie fixed?
by Anonymous Monk on Dec 07, 2015 at 12:02 UTC
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