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Date: Fri, 04 Sep 2020 20:25:49 +0200
To: David Rodrigues <david.proweb@gmail.com>
Cc: PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] __isset() and null value
From: vorismi3@fel.cvut.cz (=?UTF-8?Q?Michael_Vo=C5=99=C3=AD=C5=A1ek_-_=C4=8CVUT_FEL?=)

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Yes, this is purely to offer native/php support for it. 

When implementing custom ORM etc., we do not have any control over the
class, ie. extra method for checking property existance is not possible.


With kind regards / Mit freundlichen Grüßen / S přátelským pozdravem,

Michael Voříšek, student

On 4 Sep 2020 20:14, David Rodrigues wrote:

> Maybe you just can implements your own method to check? Like your exists()
> example.
> 
> Em sex, 4 de set de 2020 15:08, Michael Voříšek - ČVUT FEL <
> vorismi3@fel.cvut.cz> escreveu:
> 
> Your examples provide code for checking the existance of real
> properties. But how to check existance of a magic one?
> 
> The best is currently __isset(), but to comply with isset() definition,
> it should not return true when the magic property has null value, thus I
> belive, there is currently not way (provided by php language) to check
> for existance of magic property.
> 
> With kind regards / Mit freundlichen Grüßen / S přátelským pozdravem,
> 
> Michael Voříšek
> 
> On 4 Sep 2020 19:23, Marco Pivetta wrote:
> 
> Heya,
> 
> On Fri, Sep 4, 2020 at 7:03 PM Michael Voříšek - ČVUT FEL < vorismi3@fel.cvut.cz> wrote: 
> isset() returns false for null
> 
> __isset() should return the same, but then if magic property with null
> value exists, there is no way to detect it
> 
> Example: https://3v4l.org/GqUsh
> 
> this is currently an limitation of php
> 
> Ideally, we should introduce __exist() which should return true even if
> value is null and for BC autoimplement __isset() based on it and __get,
> ie.
> 
> function __isset($n) { return $this->__exist($n) && $this->__isset($n)
> !== null; } 
> I'd endorse **NOT** checking for property existence on objects that
 don't have a clearly defined interface/type: that's something for a
static
analyzer, not (usually) for runtime code. 

> If you still need to do that (anti-patterns such as stuffing things in
 `stdClass` instances), checking if a property is defined is trivial
with
reflection: 

> ```php
> <?php
> 
> class SomethingMagicAndTerriblyUgly
> {
> public $foo = null;
> private $bar = null;
> }
> 
> var_dump((new

ReflectionClass(SomethingMagicAndTerriblyUgly::class))->hasProperty('foo'));


> var_dump((new

ReflectionClass(SomethingMagicAndTerriblyUgly::class))->hasProperty('bar'));


> var_dump((new

ReflectionClass(SomethingMagicAndTerriblyUgly::class))->hasProperty('baz'));

> ```
> 
> https://3v4l.org/pVC4j
> 
> Checking if a **public** property exists at runtime is done via
 `array_key_exists()`, not via `isset()`: 

> ```php
> <?php
> 
> class SomethingMagicAndTerriblyUgly
> {
> public $foo = null;
> private $bar = null;
> }
> 
> var_dump(array_key_exists('foo', (array) (new
 SomethingMagicAndTerriblyUgly))); 

> var_dump(array_key_exists('bar', (array) (new
 SomethingMagicAndTerriblyUgly))); 

> ```
> 
> https://3v4l.org/ZLSjq
> 
> Marco Pivetta
> 
> http://twitter.com/Ocramius
> 
> http://ocramius.github.com/
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