#! perl
use strict;
use warnings;
use Internals qw(IsWriteProtected);

for (qw(literal1 literal2 literal3))
{
    print "$_\n";
    foo('wilma');
}

sub foo
{
    if (IsWriteProtected(\$_))
    {
        warn "Can't modify \$_";
    }
    else
    {
        $_ = 'fred';
    }

    goto &bar;
}

sub bar
{
    my ($name) = @_;
    print "foo --> name = $name, \$_ = $_\n";
}