package Foo;
print "Example 1\n";

sub on  { print "on $_[0]\n" }
sub run { print "run $_[0]\n" }

on foo => run { print "foo!\n" };

package Bar;
print "Example 2\n";

sub on ($@)  { print "on $_[0]\n" }
sub run (&@) { print "run $_[0]\n" }

on foo => run { print "foo!\n" };