Config child class E_NOTICE on non existent element access

[viktoras25]

So I was using Phalcon\Config class for following expressions:

if (!empty($config->some->value)) {
    die("Value does not exist");
}

And this works without any problems, which is nice. However when I try to do the same with an inherited class - I get notices "Undefined offset".

This code simulates the issue.

class C extends Phalcon\Config {}

$c1 = new Phalcon\Config();
$c2 = new C();

empty($c1->non->existing->value);
empty($c2->non->existing->value);

Notice is shown only for 2nd empty call. I'm not sure if it's a bug or restriction.

Phalcon version 1.3.0 built from ext.

[viktoras25]

I presume this may has to do with

obj->obj.ce->type != ZEND_INTERNAL_CLASS

Because Phalcon\Config class is defined in extension and might be considered internal and my custom defined classes are not.

Seems like a bug — isset() triggers the same behavior.

Or maybe not — empty() is called only on the last component (value); PHP tries to read $c->non and $c->non->existing before trying to call empty()/isset().

Internal classes understand PHP's intention to check whether the property exists (PHP passes them a special flag) but there is no way to pass that flag to __get() method.

Here's a quick test case:

<?php

error_reporting(E_ALL);

class A
{
        private $props = array();

        public function __isset($k)
        {
                echo __METHOD__, "\n";
                return isset($this->props[$k]);
        }

        public function __get($k)
        {
                echo __METHOD__, "\n";
                return $this->props[$k];
        }
}

$a = new A;
var_dump(isset($a->b->c));
var_dump(empty($a->b->c));

PHP will complain twice about Notice: Undefined index: b — it looks like this is the standard behavior.

I have implemented a workaround: if read_property/read_offset is called with BP_VAR_IS flag (intention to check if the property/dimension exists) and the class is a userspace class, the code will call first __isset()/offsetExists() and invoke __get()/offsetGet() only on success.

This adds one extra call on such isset()/empty() calls but will result in a cleaner code without any notices and warnings.

[viktoras25]

I didn't understand much about the flag, but thank you very much :) 👍