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Bug #78226 Unexpected __set behavior with typed properties
Submitted: 2019-06-28 10:26 UTC Modified: 2019-08-18 13:26 UTC
Votes:2
Avg. Score:5.0 ± 0.0
Reproduced:2 of 2 (100.0%)
Same Version:2 (100.0%)
Same OS:2 (100.0%)
From: dirk dot gerigk at tui dot com Assigned: nikic (profile)
Status: Assigned Package: Class/Object related
PHP Version: 7.4Git-2019-06-28 (Git) OS: Linux
Private report: No CVE-ID: None
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 [2019-06-28 10:26 UTC] dirk dot gerigk at tui dot com
Description:
------------
Maybe it is a not implemented yet in alpha1, 
but i found a unexpected behavior when using __set / __get.
I will only point to one issue i found. 

So, when you use __set in a class and typ-hint a property, 
the __set method is always called.


Side Note (other issue):
Is it normal that you have to make every type-hinted property nullable?
Because when you have: public string $bar; 
And do: (new A)->bar;
You get: Fatal error: Uncaught TypeError: Typed property A::$bar must be string, null used

Is that wanted in that way? 

Test script:
---------------
class A {
    public string $bar;
    public $foo;
    final public function __get($name){
        print "get_$name ";
    }
    final public function __set($name,$arg){
        print "set_$name ";
    }
}
$obj = new A;
$obj->bar='';
$obj->foo='';
var_export($obj);

Expected result:
----------------
A::__set_state(array( 'bar' => '', 'foo' => '', ))

Actual result:
--------------
set_bar A::__set_state(array( 'foo' => '', ))

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 [2019-06-28 10:43 UTC] dirk dot gerigk at tui dot com
OK, forget the side note. i have read this https://wiki.php.net/rfc/typed_properties_v2 and it is explained there.
 [2019-06-28 11:02 UTC] nikic@php.net
This is working "as intended", though I agree that the behavior is quite surprising. Typed properties start out uninitialized/unset and accessing unset properties causes calls to __get/__set.

If you can, don't use __set. If you can't, use

    public ?string $bar = null;

to explicitly initialize it the property to null, though you will have to deal with the consequences of that.

It would be nice to have a way to bypass __set when assigning to an unset property (including uninitialized typed properties), but I don't see any obvious way to support that.
 [2019-06-28 15:13 UTC] dirk dot gerigk at atraveo dot com
Thanx for the fast answer.
I have taken the time to read the https://wiki.php.net/rfc/typed_properties_v2 in detail and was suprised how complex the hole thing will be.
I think will dig into it fully (writing code), when it is implement full in the future.

But i am still curious how it will work in the future, so is there a link to a final draft of the implementation?
 [2019-06-28 15:23 UTC] dirk dot gerigk at atraveo dot com
Ignore my last question in the last comment. :-)
 [2019-07-23 07:08 UTC] wanghao at imwh dot net
The behavior is quite surprising.It make me upset.
 [2019-08-13 20:51 UTC] nikic@php.net
-Summary: Unexpected __set behavior +Summary: Unexpected __set behavior with typed properties
 [2019-08-14 12:47 UTC] tandrewbennett at hotmail dot com
For what it's worth, I think that a lot of the use cases for using __set() in userland code are based on devs trying to roll their own property accessor syntax for their entities, value objects, etc. I think this new behavior would be a non issue if we had something like this: https://wiki.php.net/rfc/propertygetsetsyntax-v1.2

I know there are differing opinions regarding the specific syntax (some prefer a C# style syntax while other prefer an ES6 based approach), but I still think it's worth mentioning here, perhaps for future releases.
 [2019-08-18 13:26 UTC] nikic@php.net
-Status: Open +Status: Assigned -Assigned To: +Assigned To: nikic
 [2019-08-18 13:26 UTC] nikic@php.net
I think we'll have to change the semantics of __set to not be called for properties that are declared but unset (or uninitialized).
 [2019-09-11 09:54 UTC] nikic@php.net
The following pull request has been associated:

Patch Name: Don't invoke __set() on accessible declared but unset properties
On GitHub:  https://github.com/php/php-src/pull/4696
Patch:      https://github.com/php/php-src/pull/4696.patch
 
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Last updated: Mon Sep 16 14:01:28 2019 UTC