my $foo;
my %hash;
$hash{'$foo'}=\$foo;
sub1 (\%hash);

##</code><code>##

sub sub1{
my $ref_from_global = shift;
my $foo=${$$ref_from_gloabl{'$$foo'}};
}

##</code><code>##

sub sub1 {
my $dat_ref = shift;
my $code_ref = shift;
eval {&\code_ref);
}