Safe / @ISA Problem

[rdw]

I've been playing around with Safe, but I've hit a problem with @ISA / inheritance, and I can't seem to work round it. I managed to strip everything right back to a very small example which shows the problem.

#! /usr/bin/perl -w

use strict;

use Safe;

my $CODE = << 'END';

package A;

sub new {
  my($class) = @_;
  bless { }, $class;
}

package B; 

our @ISA = qw(A);

END

# If I uncomment this line, everything works.
# eval $CODE;

my $safe = Safe->new();

$safe->reval($CODE);       
warn "code - $@" if $@;
$safe->reval("B->new();"); 
warn "new - $@" if $@;

When I run this, I get "Can't locate package A for @B::ISA" (twice). If I uncomment the eval, then the problem goes away - but of course in the real app, I don't want to eval the untrusted code outside of Safe (so just suggesting that I uncomment it, isn't going to help me much :-)

Can someone explain to me what's going on? Any idea how I might get round this problem?

Have fun,

rdw