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Date: Fri, 04 Sep 2020 20:07:57 +0200
To: Marco Pivetta <ocramius@gmail.com>
Cc: PHP internals <internals@lists.php.net>
In-Reply-To: <CADyq6s+pgZ1tnkLtyteuOHwmnXggDTVXEV2gRZNbQyVAoJ8uBQ@mail.gmail.com>
References: <c3fdbfe3cadde9af0e217e6880f3894e345751e28138584e698727e84590b292@mahalux.com>
 <CADyq6s+pgZ1tnkLtyteuOHwmnXggDTVXEV2gRZNbQyVAoJ8uBQ@mail.gmail.com>
Message-ID: <931ab9a3fbe85bd5c9cb083dbf0611f7ea1896fa7ddd2bce3a7e46a0630c48b6@mahalux.com>
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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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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