my $sub;

BEGIN
{
	$sub = sub {
		my ($called) = (caller(0))[3];
		warn "Called as <$called>\n";
	};

	*{ bar } = $sub;
}

my $b = \&bar;
$sub->();
*{ foo } = $sub;
foo();
bar();
$b->();
*{ baz } = $b;
baz();