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Date: Sun, 10 Apr 2022 15:30:39 +0200
Message-ID: <CADeZBNaBbdcDMiG8gtNRTQyHtg8HVaRO=ooRDxwXce7i9QZ7eQ@mail.gmail.com>
To: PHP internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="00000000000015039005dc4cd657"
Subject: Re: unset a reference of property object
From: glash.gnome@gmail.com (Glash Gnome)

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Q1: "how to modify this line to reproduce the behavior of PHP"

A1:

/* {{{ vendor_my_get_debug_info */

static HashTable*

vendor_my_get_debug_info(zend_object *object, int *is_temp)

{

    vendor_my *intern =3D ZOBJ_TO_VENDOR_MY(object);

    HashTable   *debug_info=3DNULL, *std_props=3DNULL;


    *is_temp =3D 1;

    std_props =3D zend_std_get_properties(object);

    debug_info =3D zend_array_dup(std_props);


    zval zdata;

    if (Z_ISREF(intern->data) && Z_REFCOUNT(intern->data)<2) {// If
the reference is no longer used by the PHP-user

        ZVAL_COPY(&zdata, &Z_REF(intern->data)->val);// hide reference
(for compatibility)

    } else {

        ZVAL_COPY(&zdata, &intern->data);// show reference (for debugging ?=
??)

    }

    zend_hash_str_update(debug_info, "data", sizeof("data")-1, &zdata);


    return debug_info;

} /* }}} */


Q2: "Why do I have to hide that it's a reference ?"
A2: For historical( debugging) raison, see :
https://github.com/php/php-src/blob/master/ext/standard/var.c#L202
I think it's a bad idea to show & but it doesn't really matter.

In my case I think it's best never to show the reference :
    zval zdata; ZVAL_COPY(&zdata, Z_ISREF(intern->data) ?
&Z_REF(intern->data)->val : &intern->data);
zend_hash_str_update(debug_info, "data", sizeof("data")-1, &zdata);
If I need to debug references/refcount it is better to use gdb's
pretty-print feature but no var_dump()



Le sam. 9 avr. 2022 =C3=A0 17:51, Glash Gnome <glash.gnome@gmail.com> a =C3=
=A9crit :

> Out of politeness I answer myself,
>
>
> PHP_FUNCTION(var_dump)
>  -> php_var_dump()
>      -> zend_std_get_properties_for() //                     Zend object =
handler get_properties_for
>          -> obj->handlers->get_debug_info(obj, &is_temp); // Zend object =
handler get_debug_info
>              -> zend_std_get_properties();//                 Zend object =
handler get_properties
>                  -> rebuild_object_properties()
>                      -> _zend_hash_append_ind()
>                          =3D> ZVAL_INDIRECT(&p->val, ptr); // do the tric=
k( Z_TYPE change)
> TODO: Find out how to manage the IS_INDIRECT
>
> So to reproduce the default php behavior I can implement the get_debug_in=
fo handler.
>
> I'm still trying to figure out how to modify this line :
> void my_get_debug_info() {
>     // ...
>     // Z_REFCOUNT(intern->data)=3D=3D1
>     // Z_TYPE(intern->data)=3D=3DIS_REFERENCE
>     // Z_TYPE(Z_REF(intern->data)->val)=3D=3DIS_ARRAY
>     zval zdata; ZVAL_COPY(&zdata, &intern->data);// Why do I have to hide=
 that it's a reference ?
>     zend_hash_str_update(debug_info, "data", sizeof("data")-1, &zdata);
>     // ...
>     return debug_info;
> }
>
> my_handlers.get_debug_info =3D my_get_debug_info;
>
>
> struct _my {// intern structure
>     zval data;// array of unsigned int
>     zend_object std;
> };
>
> Le sam. 9 avr. 2022 =C3=A0 15:42, Glash Gnome <glash.gnome@gmail.com> a =
=C3=A9crit :
>
>> Hello,
>>
>> I am developing a PHP extension. I can't reproduce the behavior of
>> references of Zend/PHP.
>>
>> Here is some Code illustrating Zend's behavior:
>> <?php
>> class Foo { public $baz =3D array(1);}
>> $foo =3D new Foo();
>> $ref =3D &$foo->baz;
>> $foo->baz =3D [123];//set array has reference
>> var_dump($foo);
>>
>> Output ------------------------
>> object(Foo)#1 (1) {
>> ["baz"]=3D>
>> &array(1) { [0]=3D> int(123) }
>> }
>> --------------------------------
>> Note the symbol ( &) output from the var_dump();
>>
>>
>> Now I add unset($ref) in my code
>> <?php
>> class Foo { public $baz =3D array(1);}
>> $foo =3D new Foo();
>> $ref =3D &$foo->baz;
>> //unset($ref);// kill reference
>> $foo->baz =3D [123];// set array has reference
>> unset($ref) ;// kill reference
>> var_dump($foo);
>> ------------------------
>> object(Foo)#1 (1) {
>> ["baz"]=3D>
>> array(1) { [0]=3D> int(123) }
>> }
>> --------------------------------
>>
>> Note that the symbol (&) has disappeared from the output of var_dump();
>>
>> I would like to reproduce this behavior but I don't know which method of
>> zend_object_handlers allows to remove( Z_UNREF) the reference.
>>
>> Thank you for your help
>>
>>
>>

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