<?php
class A {

    public static function getStatic()
    {
        return function () { };
    }

    public function getNoStatic()
    {
        return function () { };
    }
}

$a = new A;

$fs = A::getStatic();
$fns = $a->getNoStatic();

var_dump($fs->is_static); // true
var_dump($fns->is_static); // false