package Foo;
our $d;               # FIRST
$d = __PACKAGE__;

package Bar;
sub bar {
   print 'in ', __PACKAGE__, '::bar $d is equal to ', "$d\n";
   return;
}
our $d = __PACKAGE__; # SECOND
sub baz {
   print 'in ', __PACKAGE__, '::baz $d is equal to ', "$d\n";
   return;
}

package main;
Bar::bar();
Bar::baz();

__END__

poletti@PolettiX:~/sviluppo/perl$ perl our.pl
in Bar::bar $d is equal to Foo
in Bar::baz $d is equal to Bar