PHP extension development notes (1) Create array attributes of classes

It is very easy to initialize a class, such as the code below
MYCLASS_PROTERTY_* This is related to the macro string of define

<code>zend_class_entry *myclass_ce;

zend_function_entry myclass_methods[] = {
    PHP_FE_END
};

PHP_MINIT_FUNCTION(myext)
{

    zend_class_entry ce;

    INIT_CLASS_ENTRY(ce, <span>"MyClass"</span>, myclass_methods);
    myclass_ce = zend_register_internal_class(&amp;ce TSRMLS_CC);

    zend_<span>declare</span>_class_constant_string(myclass_ce, ZEND_STRL(MYCLASS_PROTERTY_NAME_VERSION), PHP_SLIM_VERSION);
    zend_<span>declare</span>_property_null(myclass_ce, ZEND_STRL(MYCLASS_PROTERTY_NAME_CONTAINER), ZEND_ACC_PUBLIC TSRMLS_CC);
    zend_<span>declare</span>_property_null(myclass_ce, ZEND_STRL(MYCLASS_PROTERTY_NAME_APPS), ZEND_ACC_STATIC|ZEND_ACC_PROTECTED TSRMLS_CC);
    zend_<span>declare</span>_property_null(myclass_ce, ZEND_STRL(MYCLASS_PROTERTY_NAME_NAME), ZEND_ACC_PROTECTED TSRMLS_CC);
    zend_<span>declare</span>_property_null(myclass_ce, ZEND_STRL(MYCLASS_PROTERTY_NAME_ERROR), ZEND_ACC_PROTECTED TSRMLS_CC);
    zend_<span>declare</span>_property_null(myclass_ce, ZEND_STRL(MYCLASS_PROTERTY_NAME_NOTFOUND), ZEND_ACC_PROTECTED TSRMLS_CC);
    zend_<span>declare</span>_property_null(myclass_ce, ZEND_STRL(MYCLASS_PROTERTY_NAME_MIDDLEWARE), ZEND_ACC_PROTECTED TSRMLS_CC);

    <span>return</span> SUCCESS;
}</code>

The above codes are all simple properties.
When trying to initialize the attributes of an array for the class myclass, it failed. The code relative to PHP is as follows

<code><span><span>class</span><span>MyClass</span> {
    public $myArray = array<span>()</span>;
}


/* 对应的<span>C</span>代码 */

zval *myArray;
<span>MAKE_STD_ZVAL</span><span>(<span>myArray</span>)</span>;
array_init<span>(<span>myArray</span>)</span>;

zend_declare_property<span>(<span>myclass_ce</span>, <span>ZEND_STRL(MYCLASS_PROTERTY_NAME_MYCLASS)</span>, <span>myArray</span>, <span>ZEND_ACC_PUBLIC</span><span>TSRMLS_CC</span>)</span>;</span></code>

No problem was found when the above C code was mutated. When new MyClass() was executed, There is a problem, the error is as follows:

<code>Internal zval<span>'s</span> can<span>'t</span> be arrays, objects <span>or</span> resources</code>

Look at the source code of zend as follows:

<code><span>if</span> (ce-&gt;<span><span>type</span> &amp; <span>ZEND_INTERNAL_CLASS</span>) <span>{
     <span>switch</span>(<span>Z_TYPE_P(property)</span>) {
         <span>case</span><span>IS_ARRAY</span>:
         <span>case</span><span>IS_CONSTANT_ARRAY</span>:
         <span>case</span><span>IS_OBJECT</span>:
         <span>case</span><span>IS_RESOURCE</span>:
             <span>zend_error</span>(<span>E_CORE_ERROR</span>, "<span>Internal</span><span>zval's</span><span>can't</span><span>be</span><span>arrays</span>, <span>objects</span><span>or</span><span>resources</span>");
             <span>break</span>;
         <span>default</span>:
             <span>break</span>;
     }</span></span>
 }</code>

When we call zend_register_internal_class, myclass_ce has been initialized to ZEND_INTERNAL_CLASS, and the myArray parameter of zend_declare_property at this time is of type IS_ARRAY. So this error occurred.

Why does such an error occur?

The result I got after searching is: http://grokbase.com/t/php/php-internals/07a4b14xvb/php-dev-how-declare-protected-array-property-at-internal-class-properly this It is the result of 2007. I am using the PHP5.4 version, and I still have this problem for the time being. The article also gives a method to implement array attributes in disguise, by implementing it in the constructor.

<code>PHP_METHOD(myclass, __construct) {
    zval <span>*apps</span>, <span>*pThis</span>;
    pThis = getThis();
    MAKE_STD_ZVAL(apps);
    array_init(apps);
    add_property_zval_ex(pThis, ZEND_STRL(SLIM_SLIM_PROTERTY_NAME_APPS), apps);
}</code>

The corresponding php code for this implementation

<code><span><span>class</span><span>MyClass</span> {</span><span><span>function</span><span>__construct</span><span>()</span> {</span><span>$this</span>-&gt;app = <span>array</span>();  
    }
}</code>

The above introduces the PHP extension development notes (1) Array attributes of the created class, including aspects of the content. I hope it will be helpful to friends who are interested in PHP tutorials.