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Date: Thu, 26 May 2016 12:57:39 +0100
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Subject: Re: [PHP-DEV] [RFC][Vote] Typed Properties
From: rowan.collins@gmail.com (Rowan Collins)

On 26/05/2016 11:49, Fleshgrinder wrote:
> On 5/26/2016 12:39 PM, Rowan Collins wrote:
>> On 26/05/2016 11:16, Fleshgrinder wrote:
>>>   $o = (object) ['x' => null];
>>>   var_dump(isset($a->x));              // false
>>>   var_dump(property_exists($a, 'x'));  // true
>>
>> Apart from a typo in your example (you change from $o to $a), this is
>> already the current behaviour, and always has been: https://3v4l.org/NeqGl
>>
>> isset() is really very simple: if the thing your accessing would give
>> you the value null, it returns false, otherwise it returns true.
>>
>> Regards,
>
> Now I feel stupid but I guess I got lost myself. :P

Heh, no worries, easily done. :)


> This means it is even simpler, we just have to add the E_NOTICE and be
> done with it.
>
>   $g = new class { public $x; };
>
>   var_dump($g->x);                     // null + E_NOTICE Uninitialized
>   var_dump(isset($g->x));              // false
>   var_dump(property_exists($g, 'x'));  // true
>   var_dump(is_null($g->x));            // true + E_NOTICE Uninitialized
>   var_dump($g->x == null);             // true + E_NOTICE Uninitialized
>   var_dump($g->x === null);            // true + E_NOTICE Uninitialized
>
> This behavior would be true for all variations:
>
>   class A {
>
>     var $x;
>
>     public $x;
>
>     public int $x;
>
>     public ?int $x;
>
>   }
>
> No notice for the following:
>
>   class A {
>
>     var $x = null;
>
>     public $x = null;
>
>     public int $x = 0;
>
>     public ?int $x = null;
>
>   }
>


I am definitely in favour of this from a language point of view. The 
notice is warning about *initialization*, not *declaration*, so it makes 
sense to warn on "var $foo" and not "var $foo = null".

The only thing I'm not sure is what the impact would have on the 
internals, which may be why it doesn't already work that way. With a 
simple variable the notice can be easily raised based on the variable 
name not being in the current symbol table; with an object property, the 
name *is* in the relevant table, because it's been *declared* even 
though it hasn't been *initialized*. Thus you need some extra flag to 
track that a declared property exists but has never been written to.

But it sounds like typed properties require adding some such overhead 
anyway...

Regards,
-- 
Rowan Collins
[IMSoP]