PHP variable class static method call

Question

I have a property that stores a class name as a string. I then want to use this to call a static method of said class. As far as I know, this is possible since PHP 5.3. I am running 5.6.x on a vagrant box.

I want to do this:

$item = $this->className::getItem($id);

But I get the following error:

Parse error: syntax error, unexpected '::' (T_PAAMAYIM_NEKUDOTAYIM)...

The following works fine:

$c = $this->className;
$item = $c::getItem($id);

Any idea why? Is this not the same thing?

class is a reserved (key)word in OOP, far as I remember. php.net/manual/en/reserved.keywords.php — Funk Forty Niner
– Funk Forty Niner, Commented Dec 1, 2016 at 20:08
Because line $this->class::getItem($id); is not clear. What is it {$this->class}::getItem($id); or $this->{class::getItem($id)}; Who can tell? — u_mulder
– u_mulder, Commented Dec 1, 2016 at 20:09
What does this mean? “Parse error: syntax error, unexpected T_PAAMAYIM_NEKUDOTAYIM” — Funk Forty Niner
– Funk Forty Niner, Commented Dec 1, 2016 at 20:14
Ya I realized class was reserved and updated my code to use a non-reserved word. I still had the issue so I left the post alone. I have edited it now to clear up that I am no longer using the reserved word. — Gurnzbot
– Gurnzbot, Commented Dec 1, 2016 at 20:21
well that stealthy edit blows my comment right out of the water, doesn't it? — Funk Forty Niner
– Funk Forty Niner, Commented Dec 1, 2016 at 20:21

JOUM · Accepted Answer · 2016-12-01 20:19:23Z

2

The problem is that you are access are property from a class in the first useage, but then in the second try you are parsing the value of the class property (into $c), what is a classname as string, and this can used for static calls to static class functions. The first try, trys to access the static method on an string (the class property).

class a {
     static function b(){echo'works';}
}
$a='a';
$a::b();

But the real issue of the error is, that this ->FooBar:: is an syntax error in PHP.

answered Dec 1, 2016 at 20:19

JOUM

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Comments

Antonio Alexandre · Accepted Answer · 2016-12-02 13:14:37Z

JOUM is completely right! Based on his answer I wrote a class like a fabric.

Interface GetItem
{
    public static function getItem($id);
}

Abstract Class Item
{
    private $id;

    function __construct($id)
    {
        $this->id = $id;
    }
}

Class ItemA extends Item implements GetItem
{

    public static function getItem($id)
    {
        $item = new ItemA($id);
        return $item;
    }
}

Class ItemB extends Item implements GetItem
{

    public static function getItem($id)
    {
        $item = new ItemB($id);
        return $item;
    }
}    


Class Fabric
{
    function fabricItem($classname,$id)
    {
        $item = $classname::getItem($id);

        return $item;
    }
}


$fabric = new Fabric();

$a = $fabric->fabricItem("ItemA",3);
$b = $fabric->fabricItem("ItemB",4);    


var_dump($fabric);
var_dump($a);
var_dump($b);

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