class A {
    function __construct() { 
        $this->func1 = function() { return "Foo"; };
    }
    function __construct(array $funcs) {
        foreach($funcs as $key => $val) {
            
        }
    }
}

$a = new A();

echo $a->func1();

$b = new A(array('func1' => function() { return "bar"; }));

echo $b->func1();