use strict;
my $var = 'Test::foo';
no strict 'refs'; # we need to leave use strict
*$var = sub {print "Bar\n";};
use strict; # turn it back on

##</code><code>##

package SafeCaller;

sub safe_caller { return caller(@_) if caller_allowed(); }
# disallow everyone from using safe_caller
sub caller_allowed { reutrn 0; }