[转]自己写PHP扩展之创建一个类

原文：http://www.imsiren.com/archives/572

比如我们要创建一个类..PHP代码如下

class Person {

public $name;

public $age;

public function __construct() {

echo "construct is running!

";

}

public function __destruct() {

echo "

destruct is running!";

}

public function getproperty($key) {

echo $this->$key;

}

public function setproperty($key,$val) {

$this->$key = $val;

}

用PHP来做,很简单..
那么用PHP扩展来写该怎么做?
OK.
1.在php_siren.h里面声明类

PHP_METHOD(Person,__construct);

PHP_METHOD(Person,__destruct);

PHP_METHOD(Person,setproperty);

PHP_METHOD(Person,getproperty);

PHP_METHOD宏.
PHP_METHOD 等于ZEND_METHOD
这个宏接受两个参数,第一个是类名,第二个是类的方法

#define ZEND_METHOD(classname, name) ZEND_NAMED_FUNCTION(ZEND_MN(classname##_##name))

#define INTERNAL_FUNCTION_PARAMETERS int ht, zval *return_value, zval **return_value_ptr, zval *this_ptr, int return_v    alue_used TSRMLS_DC

//最后等于

void name(int ht, zval *return_value, zval **return_value_ptr, zval *this_ptr, int return_v alue_used TSRMLS_DC )

这个宏是用来声明我们的方法…
2.设置接收的参数
我们的方法如果需要接受参数.那么就要执行

ZEND_BEGIN_ARG_INFO_EX(arg_person_info,0,0,2)

ZEND_ARG_INFO(0,name)

ZEND_END_ARG_INFO()

详细讲这几个宏之前先看看zend_arg_info

typedef struct _zend_arg_info {

const char *name; //参数名称

zend_uint name_len;//长度

const char *class_name; //所属类名

zend_uint class_name_len; //类名长度

zend_bool array_type_hint;

zend_bool allow_null; //允许为空

zend_bool pass_by_reference; //引用传值

zend_bool return_reference; //引用返回

int required_num_args; //参数个数

} zend_arg_info;

ZEND_BEGIN_ARG_INFO_EX定义在Zend/zend_API.h

#define ZEND_BEGIN_ARG_INFO_EX(name, pass_rest_by_reference, return_reference, required_num_args) \

static const

zend_arg_info name[] = {                                                                                                                                           \

{ NULL, 0, NULL, 0, 0, 0, pass_rest_by_reference, return_reference, required_num_args },

很明显声明一个zend_arg_info的数组name,然后初始化结构体的值
ZEND_ARG_INFO(0,name)的定义如下

1	`#define ZEND_ARG_INFO(pass_by_ref, name) { #name, sizeof(#name)-1, NULL, 0, 0, 0, pass_by_ref, 0, 0 },`

这三个宏执行代码等于

static const

zend_arg_info name[] = {                                                                                                                                                    { NULL, 0, NULL, 0, 0, 0, pass_rest_by_reference, return_reference, required_num_args },

{ #name, sizeof(#name)-1, NULL, 0, 0, 0, pass_by_ref, 0, 0 },

};

3.创建zend_function_entry结构数组

const zend_function_entry person_functions[]={

PHP_ME(Person,__construct,NULL,ZEND_ACC_PUBLIC|ZEND_ACC_CTOR)

PHP_ME(Person,__destruct,NULL,ZEND_ACC_PUBLIC|ZEND_ACC_DTOR)

PHP_ME(Person,getproperty,arg_person_info,ZEND_ACC_PUBLIC)

PHP_ME(Person,setproperty,arg_person_info,ZEND_ACC_PUBLIC)

PHP_FE_END

};

zend_function_entry定义如下

typedef struct _zend_function_entry {

const char *fname; //函数名称

void (*handler)(INTERNAL_FUNCTION_PARAMETERS);

const struct _zend_arg_info *arg_info;//参数

zend_uint num_args;//参数个数

zend_uint flags;//标示PUBLIC ?PRIVATE ?PROTECTED

} zend_function_entry;

PHP_ME宏接收四个参数
1 类名,
2 方法名,
3 zend_arg_info 的参数列表,

ZEND_ACC_PUBLIC ZEND_ACC_PRIVATE ZEND_ACC_PROTECTED是我们类里面的三个访问权限
ZEND_ACC_CTOR标示构造函数
ZEND_ACC_DTOR标示析构函数
4.修改PHP_MINIT_FUNCTION
前面我们说过 PHP_MINIT_FUNCTION是在模块启动的时候执行的函数
首先创建一个全局指针 zend_class_entry *person_ce;
在PHP_MINIT_FUNCTION加入如下代码

zend_class_entry person;

INIT_CLASS_ENTRY(person,"Person",person_functions);

person_ce=zend_register_internal_class_ex(&person,NULL,NULL TSRMLS_CC);

zend_declare_property_null(person_ce,ZEND_STRL("name"),ZEND_ACC_PUBLIC TSRMLS_CC);

1行创建一个zend_class_entry对象person.
zend_class_entry这个结构体前面也讲过 PHP内核研究之类的实现
2行初始化zend_class_entry 它执行了如下代码

{                                                                                                                       \

int

_len = class_name_len;                                                              \

class_container.name = zend_strndup(class_name, _len); \

class_container.name_length = _len;                                             \

class_container.builtin_functions = functions; \

class_container.constructor = NULL;                                             \

class_container.destructor = NULL;                                              \

class_container.clone = NULL;                                                   \

class_container.serialize = NULL;                                               \

class_container.unserialize = NULL;                                             \

class_container.create_object = NULL; \

class_container.interface_gets_implemented = NULL; \

class_container.get_static_method = NULL; \

class_container.__call = handle_fcall; \

class_container.__callstatic = NULL; \

class_container.__tostring = NULL;                                              \

class_container.__get = handle_propget; \

class_container.__set = handle_propset; \

class_container.__unset = handle_propunset; \

class_container.__isset = handle_propisset; \

class_container.serialize_func = NULL; \

class_container.unserialize_func = NULL; \

class_container.serialize = NULL;                                               \

class_container.unserialize = NULL;                                             \

class_container.parent = NULL;                                                  \

class_container.num_interfaces = 0;                                             \

class_container.interfaces = NULL;                                              \

class_container.get_iterator = NULL; \

class_container.iterator_funcs.funcs = NULL; \

class_container.module = NULL;                                                  \

}

可以对应文章>> PHP内核研究之类的实现来分析
zend_declare_property_null(person_ce,ZEND_STRL(“name”),ZEND_ACC_PUBLIC TSRMLS_CC);
创建一个值为NULL的属性
第一个参数是类名,第二个参数是属性名称,第三个参数是属性名的长度,因为ZEND_STRL宏定义了长度,所以这里不用再传递长度.
第四个参数是属性的访问权限.
还有其他几个函数用来创建不同类型的属性