11.2 PHP中的面向对象（二）
在上一节里我们已经看了下如何操作一个对象的方法，这一节主要描述与对象属性有关的东西。有关如何对它进行定义的操作我们已经在上一章中描述过了，这里不再叙述，只讲对其的操作。
读取对象的属性
ZEND_API zval *zend_read_property(zend_class_entry *scope, zval *object, char *name, int name_length, zend_bool silent TSRMLS_DC);
ZEND_API zval *zend_read_static_property(zend_class_entry *scope, char *name, int name_length, zend_bool silent TSRMLS_DC);
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zend_read_property函数用于读取对象的属性，而zend_read_static_property则用于读取静态属性。可以看出，静态属性是直接保存在类上的，与具体的对象无关。 silent参数：
- 0: 如果属性不存在，则抛出一个notice错误。
- 1: 如果属性不存在，不报错。
更新对象的属性
ZEND_API void zend_update_property(zend_class_entry *scope, zval *object, char *name, int name_length, zval *value TSRMLS_DC);
ZEND_API int zend_update_static_property(zend_class_entry *scope, char *name, int name_length, zval *value TSRMLS_DC);
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zend_update_property用来更新对象的属性，zend_update_static_property用来更新类的静态属性。如果对象或者类中没有相关的属性，函数将自动的添加上。
读写对象与类属性的实例
假设我们已经在扩展中定义好下面的类：
class baby
{
public $age;
public static $area;
public function __construct($age, $area)
{
$this->age = $age;
self::$area = $area;
var_dump($this->age, self::$area);
}
}
ZEND_METHOD(baby, __construct)
{
zval *age, *area;
zend_class_entry *ce;
ce = Z_OBJCE_P(getThis());
if( zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "zz", &age, &area) == FAILURE )
{
printf("Error\n");
RETURN_NULL();
}
zend_update_property(ce, getThis(), "age", sizeof("age")-1, age TSRMLS_CC);
zend_update_static_property(ce, "area", sizeof("area")-1, area TSRMLS_CC);
age = NULL;
area = NULL;
age = zend_read_property(ce, getThis(), "age", sizeof("age")-1, 0 TSRMLS_DC);
php_var_dump(&age, 1 TSRMLS_CC);
area = zend_read_static_property(ce, "area", sizeof("area")-1, 0 TSRMLS_DC);
php_var_dump(&area, 1 TSRMLS_CC);
}
//为类添加age 和 area属性
PHP_MINIT_FUNCTION(say_hello)
{
zend_class_entry ce;
INIT_CLASS_ENTRY(ce,"baby",myclass_method);
baby_ce = zend_register_internal_class(&ce TSRMLS_CC);
zend_declare_property_null(baby_ce, "age", strlen("age"), ZEND_ACC_PUBLIC TSRMLS_CC);
zend_declare_property_null(baby_ce, "area", strlen("area"), ZEND_ACC_STATIC|ZEND_ACC_PUBLIC TSRMLS_CC);
return SUCCESS;
}
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ZEND_API int zend_update_static_property_null(zend_class_entry *scope, char *name, int name_length TSRMLS_DC); ZEND_API int zend_update_static_property_bool(zend_class_entry *scope, char *name, int name_length, long value TSRMLS_DC); ZEND_API int zend_update_static_property_long(zend_class_entry *scope, char *name, int name_length, long value TSRMLS_DC); ZEND_API int zend_update_static_property_double(zend_class_entry *scope, char *name, int name_length, double value TSRMLS_DC); ZEND_API int zend_update_static_property_string(zend_class_entry *scope, char *name, int name_length, const char *value TSRMLS_DC); ZEND_API int zend_update_static_property_stringl(zend_class_entry *scope, char *name, int name_length, const char *value, int value_length TSRMLS_DC);
## links
* 11.1 [生成对象的实例](<11.1.md>)
* 11.3 [小结](<11.3.md>)
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