<?
class A{
public function do_a(){ return 'a_done';}
public function do_b(){ return 'b_done';}
}
$System = new A;
$method_a = $System->do_a;
$method_b = $System->do_b;
echo 'this was the result of ' . $method_a();
echo 'this was the result of ' . $method_b();