Why is this allowed in PHP?

Question

Why doesn't PHP throw an error on line 7?

<?php

class Test {
    public function __construct(){

        $name = 123;
        $this->$name = 'Test';
        var_dump($this->$name);


        $this->123 = 'Test2';
        var_dump($this->123);

    }
}

$test = new Test();
var_dump($test);

I always thought, that class fields couldn't start with numbers. But that doesn't seem to be the case if the number is in a variable.

I don't believe it even gets to execute line 7.... parse error triggers first while it's parsing/compiling — Mark Baker, Jul 01 '15 at 16:18
However, defining properties dynamically bypasses that rule.... and necessarily so, for some of the XML that I've seen (with numeric names for elements) when converting to SimpleXML — Mark Baker, Jul 01 '15 at 16:21
Interesting question! I din't expect this either. Shud b called as a bug rathr than feature. — Gogol, Jul 01 '15 at 17:23

JohnnyFaldo · Accepted Answer · 2015-07-02T09:50:00.123

5

I believe this is because of the dynamic nature of PHP variables.

If you read the vardump of the defined class property:

 object(Test)#1 (1) { ["123"]=> string(4) "Test" }

You can see its (index is) a string, not a integer as you're expecting it to be

edited Jul 02 '15 at 09:50

answered Jul 01 '15 at 16:22

JohnnyFaldo

4,121
4
19
29

So behind the scenes it gets converted to a string? That's good to know! – TMH Jul 02 '15 at 08:47

Why is this allowed in PHP?

1 Answers1