$code = sub { wantarray ? ('foot','ball') : 'soccer' };

sub foo {
    my ($r, @r);                          # two possible returns
    (wantarray ? (@r) : ($r)) =           # slight of hand to get the correct lvalue 
        (wantarray ? (&$code) : &$code);  # and make the correct rvalue call
    return $r || @r                       # return that which is defined
}

$x = &foo();
@x = &foo();

print $x;
print @x;

##</code><code>##

$code = sub { wantarray ? ("foot","ball") : "soccer" };

sub foo { wantarray ? (&$code) : &$code }

$x = &foo();
@x = &foo();

print $x;
print @x;