PHP-CPP是一个用于开发PHP扩展的C++库。本节讲解如何在C++中实现PHP类。
类和对象
类和对象
怎样在PHP-CPP里写出PHP的类呢？很简单，看下面的例子：main.cpp
/** * User: 公众号: 飞鸿影的博客(fhyblog) * Date: 2018/7 */#include <time.h>#include <phpcpp.h>/** * ?Counter class that can be used for counting */class Counter : public Php::Base{private: ???/** ????* ?The initial value ????* ?@var ???int ????*/ ???int _value = 0;public: ???/** ????* ?C++ constructor and destructor ????*/ ???Counter() = default; ???virtual ~Counter() = default; ???/** ????* ?Update methods to increment or decrement the counter ????* ?Both methods return the NEW value of the counter ????* ?@return int ????*/ ???Php::Value increment() { return ++_value; } ???Php::Value decrement() { return --_value; } ???/** ????* ?Method to retrieve the current counter value ????* ?@return int ????*/ ???Php::Value value() const { return _value; } ???????//类的静态成员函数 ???static Php::Value gettime() {return time(NULL);}};/** * ?Switch to C context to ensure that the get_module() function * ?is callable by C programs (which the Zend engine is) */extern "C" { ???/** ????* ?Startup function that is called by the Zend engine ?????* ?to retrieve all information about the extension ????* ?@return void* ????*/ ???PHPCPP_EXPORT void *get_module() { ???????????// 必须是static类型，因为扩展对象需要在PHP进程内常驻内存 ???????static Php::Extension extension("helloworld", "1.0.0"); ???????????????//初始化导出类 ???????Php::Class<Counter> counter("Counter"); ???????????????//注册导出类的可访问普通函数 ???????counter.method<&Counter::increment> ("increment"); ???????counter.method<&Counter::decrement> ("decrement"); ???????counter.method<&Counter::value> ("value"); ???????????????//注册导出类的可访问静态函数 ???????counter.method<&Counter::gettime>("gettime"); ???????//注册导出类，使用右值引用方式，优化资源使用 ???????extension.add(std::move(counter)); ???????????????// 返回扩展对象指针 ???????return extension; ???}}首先，C++类必须继承自Php::Base；其次，当我们将类添加到扩展对象时，还必须指定要从PHP访问的所有方法；最后再注册导出类。
我们先测试：
/** * User: 公众号: 飞鸿影的博客(fhyblog) * Date: 2018/7 */$counter = new Counter;echo 'result of increment() = '. $counter->increment() . PHP_EOL;echo 'result of increment() = '. $counter->increment() . PHP_EOL;echo 'result of decrement() = '. $counter->decrement() . PHP_EOL;echo 'result of value() = '. $counter->value() . PHP_EOL;echo 'result of gettime() = '. Counter::gettime() . PHP_EOL;输出：
result of increment() = 1result of increment() = 2result of decrement() = 1result of value() = 1result of gettime() = 1531621728访问修饰符
我们还可以对导出的方法添加访问修饰符：
//初始化导出类Php::Class<Counter> counter("Counter");//注册导出类的可访问普通函数counter.method<&Counter::increment> ("increment", Php::Private, { ???Php::ByVal("a", Php::Type::Numeric)});counter.method<&Counter::decrement> ("decrement", Php::Protected, { ???Php::ByVal("a", Php::Type::Numeric)});counter.method<&Counter::value> ("value");Php::Class::method第二个参数支持设置访问修饰符，默认是public；第三个参数和普通函数一样，支持设置参数类型。
支持的访问修饰符：
extern PHPCPP_EXPORT const int Static;extern PHPCPP_EXPORT const int Abstract;extern PHPCPP_EXPORT const int Final;extern PHPCPP_EXPORT const int Public;extern PHPCPP_EXPORT const int Protected;extern PHPCPP_EXPORT const int Private;extern PHPCPP_EXPORT const int Const;有一点需要注意：C++里要导出的方法，必须全是Public的， 即使我们在PHP中将它们标记为私有或受保护。因为我们写的方法由PHP-CPP库调用，如果将它们设为私有，它们将对库不可见。
抽象类、Final类
声明类为Final很简单，只需要在初始化导出类的时候声明一下即可：
Php::Class<Counter> counter("Counter", Php::Final);那么怎么声明一个抽象类呢？上面的例子里Php::Class::method都传入了真正的C ++方法的地址，但是抽象方法通常没有实现，那么我们需要怎么提供指向方法的指针？幸运的是，在PHP-CPP里注册抽象方法不用提供指向C ++方法的指针。
示例：
抽象类原申明：
/** * User: 公众号: 飞鸿影的博客(fhyblog) * Date: 2018/7 */#include <phpcpp.h>//类声明class MyAbstract : public Php::Base{};extern "C" { ???????PHPCPP_EXPORT void *get_module() ????{ ???????// 必须是static类型，因为扩展对象需要在PHP进程内常驻内存 ???????static Php::Extension extension("helloworld", "1.0.0"); ???????????????//初始化导出类 ???????Php::Class<MyAbstract> my_abstract("MyAbstract", Php::Abstract); ???????????????//注册抽象方法：如果不给出C++方法的地址，该方法自动变成抽象方法 ???????my_abstract.method("myAbstractMethod", { ????????????Php::ByVal("a", Php::Type::String, true) ????????}); ???????????????extension.add(std::move(my_abstract)); ???????????????// 返回扩展对象指针 ???????return extension; ???}}我们在test.php尝试去实例化MyAbstract类，提示：
PHP Fatal error: ?Uncaught Error: Cannot instantiate abstract class MyAbstract注：官方示例里初始化导出类里没有加
Php::Abstract,测试的时候发现还是可以实例化的，只是调用抽象方法才报错。
构造函数和析构函数
在C++代码里，PHP的构造函数和析构函数本质上是普通方法。明白了这点，就不难实现了。
示例：
/** * User: 公众号: 飞鸿影的博客(fhyblog) * Date: 2018/7 */#include <phpcpp.h>/** * ?Simple counter class */class Counter : public Php::Base{private: ???/** ????* ?Internal value ????* ?@var int ????*/ ???int _value = 0;public: ???/** ????* ?c++ constructor ????*/ ???Counter() = default; ???/** ????* ?c++ destructor ????*/ ???virtual ~Counter() = default; ???/** ????* ?php "constructor" ????* ?@param ?params ????*/ ???void __construct(Php::Parameters ¶ms) ???{ ???????// copy first parameter (if available) ???????if (!params.empty()) _value = params[0]; ???} ???/** ????* ?functions to increment and decrement ????*/ ???Php::Value increment() { return ++_value; } ???Php::Value decrement() { return --_value; } ???Php::Value value() const { return _value; }};/** * ?Switch to C context so that the get_module() function can be * ?called by C programs (which the Zend engine is) */extern "C" { ???/** ????* ?Startup function for the extension ????* ?@return void* ????*/ ???PHPCPP_EXPORT void *get_module() { ???????static Php::Extension myExtension("my_extension", "1.0"); ???????// description of the class so that PHP knows which methods are accessible ???????Php::Class<Counter> counter("Counter"); ???????counter.method<&Counter::__construct>("__construct"); ???????counter.method<&Counter::increment>("increment"); ???????counter.method<&Counter::decrement>("decrement"); ???????counter.method<&Counter::value>("value"); ???????// add the class to the extension ???????myExtension.add(std::move(counter)); ???????// return the extension ???????return myExtension; ???}}如果需要构造函数为私有的，只需要在注册的时候加个flag：
counter.method<&Counter::__construct>("__construct", Php::Private);如果要禁止被clone，可以：
// alternative way to make an object unclonablecounter.method("__clone", Php::Private);接口
接口(Interface)由于不需要具体方法的实现，我们可以通过与定义类的方式类似的方式来实现。唯一的区别是我们不使用Php::Class<YourClass>，而是一个Php::Interface实例。
//初始化Php::Interface interface("MyInterface");//添加成员方法interface.method("myMethod", { ????Php::ByVal("value", Php::Type::String, true) });//注册到扩展extension.add(std::move(interface));继承
implement 实现
我们除了可以在PHP代码去实现接口或者继承类，也可以在C++里实现。该Php::Class<YourClass>对象有extends()和implements()，可用于指定基类和实现的接口。我们需要传入之前配置的类或接口。我们来看一个例子。
/** * User: 公众号: 飞鸿影的博客(fhyblog) * Date: 2018/7 */#include <phpcpp.h>#include <iostream>class MyClass : public Php::Base{ ???public: ???????Php::Value myMethod(Php::Parameters ¶ms){ ???????????Php::out << "MyClass" << std::endl; ???????????return params; ???????}};extern "C" { ???????PHPCPP_EXPORT void *get_module() ????{ ???????static Php::Extension extension("helloworld", "1.0.0"); ???????????????//定义接口 ???????Php::Interface interface("MyInterface"); ???????interface.method("myMethod", { ????????????Php::ByVal("value", Php::Type::String, true) ????????}); ???????extension.add(std::move(interface)); ???????// 注册一个自定义类 ???????Php::Class<MyClass> myClass("MyClass"); ???????// 实现接口定义 ???????myClass.implements(interface); ???????myClass.method<&MyClass::myMethod>("myMethod", { ???????????Php::ByVal("value", Php::Type::String, true) ????????}); ???????extension.add(std::move(myClass)); ???????????????// 返回扩展对象指针 ???????return extension; ???}}测试：
$obj = new MyClass();var_dump($obj->myMethod(11));extends 继承
PHP的继承与C++的继承没有直接关系，必须显示使用Php::Class::extends()进行继承。
还是接着上面的例子说明。
/** * User: 公众号: 飞鸿影的博客(fhyblog) * Date: 2018/7 */#include <phpcpp.h>#include <iostream>class MyClass : public Php::Base{ ???public: ???????Php::Value myMethod(Php::Parameters ¶ms){ ???????????Php::out << "MyClass" << std::endl; ???????????return params; ???????}};class MySubClass : public Php::Base{};extern "C" { ???????PHPCPP_EXPORT void *get_module() ????{ ???????static Php::Extension extension("helloworld", "1.0.0"); ???????????????//定义接口 ???????Php::Interface interface("MyInterface"); ???????interface.method("myMethod", { ????????????Php::ByVal("value", Php::Type::String, true) ????????}); ???????????????// 注册一个自定义类 ???????Php::Class<MyClass> myClass("MyClass"); ???????// 实现接口定义 ???????myClass.implements(interface); ???????myClass.method<&MyClass::myMethod>("myMethod", { ???????????Php::ByVal("value", Php::Type::String, true) ????????}); ???????????????Php::Class<MySubClass> mySubClass("MySubClass"); ???????mySubClass.extends(myClass); ???????????????extension.add(std::move(interface)); ???????extension.add(std::move(mySubClass)); ???????extension.add(std::move(myClass)); ???????????????// 返回扩展对象指针 ???????return extension; ???}}注：注册类(
extension.add)需要放到extends方法的后面，也就是不能先注册父类再使用extends，否则无法继承。建议实际编程的时候注册统一放到最后面。
魔术方法
在PHP-CPP里，仅__construct()需要显示的在get_module()里注册，其他的魔术方法像__get()、__set()、__call()等都不需要注册。
/** * User: 公众号: 飞鸿影的博客(fhyblog) * Date: 2018/7 */#include <phpcpp.h>/** * ?A sample class, that has some pseudo properties that map to native types */class User : public Php::Base{private: ???/** ????* ?Name of the user ????* ?@var ???std::string ????*/ ???std::string _name; ???/** ????* ?Email address of the user ????* ?@var ???std::string ????*/ ???std::string _email;public: ???/** ????* ?C++ constructor and C++ destructpr ????*/ ???User() = default; ???virtual ~User() = default; ???/** ????* ?Get access to a property ????* ?@param ?name ???????Name of the property ????* ?@return Value ??????Property value ????*/ ???Php::Value __get(const Php::Value &name) ???{ ???????// check if the property name is supported ???????if (name == "name") return _name; ???????if (name == "email") return _email; ???????// property not supported, fall back on default ???????return Php::Base::__get(name); ???} ???/** ????* ?Overwrite a property ????* ?@param ?name ???????Name of the property ????* ?@param ?value ??????New property value ????*/ ???void __set(const Php::Value &name, const Php::Value &value) ????{ ???????// check the property name ???????if (name == "name") ????????{ ???????????// store member ???????????_name = value.stringValue(); ???????} ???????// we check emails for validity ???????else if (name == "email") ???????{ ???????????// store the email in a string ???????????std::string email = value; ???????????// must have a '@' character in it ???????????if (email.find('@') == std::string::npos) ????????????{ ???????????????// email address is invalid, throw exception ???????????????throw Php::Exception("Invalid email address"); ???????????} ???????????// store the member ???????????_email = email; ???????} ???????// other properties fall back to default ???????else ???????{ ???????????// call default ???????????Php::Base::__set(name, value); ???????} ???} ???/** ????* ?Check if a property is set ????* ?@param ?name ???????Name of the property ????* ?@return bool ????*/ ???bool __isset(const Php::Value &name) ????{ ???????// true for name and email address ???????if (name == "name" || name == "email") return true; ???????// fallback to default ???????return Php::Base::__isset(name); ???} ???/** ????* ?Remove a property ????* ?@param ?name ???????Name of the property to remove ????*/ ???void __unset(const Php::Value &name) ???{ ???????// name and email can not be unset ???????if (name == "name" || name == "email") ????????{ ???????????// warn the user with an exception that this is impossible ???????????throw Php::Exception("Name and email address can not be removed"); ???????} ???????// fallback to default ???????Php::Base::__unset(name); ???}};/** * ?Switch to C context to ensure that the get_module() function * ?is callable by C programs (which the Zend engine is) */extern "C" { ???/** ????* ?Startup function that is called by the Zend engine ?????* ?to retrieve all information about the extension ????* ?@return void* ????*/ ???PHPCPP_EXPORT void *get_module() { ???????// extension object ???????static Php::Extension myExtension("my_extension", "1.0"); ???????// description of the class so that PHP knows ????????// which methods are accessible ???????Php::Class<User> user("User"); ???????// add the class to the extension ???????myExtension.add(std::move(user)); ???????// return the extension ???????return myExtension; ???}}测试：
<?php/** * User: 公众号: 飞鸿影的博客(fhyblog) * Date: 2018/7 */// initialize user and set its name and email address$user = new User();$user->name = "John Doe";$user->email = "john.doe@example.com";// show the email addressecho($user->email."\n");// remove the email address (this will cause an exception)unset($user->email);?>（未完待续）
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PHP-CPP开发扩展（五）
原文地址：https://www.cnblogs.com/52fhy/p/9388764.html