Lio*_*rom 97 php oop nested class inner-classes
我正在为我的新网站建立一个用户类,但是这次我想要以不同的方式构建它...
我知道C++,Java甚至Ruby(可能还有其他编程语言)允许在主类中使用嵌套/内部类,这样可以使代码更加面向对象和组织.
在PHP中,我想做这样的事情:
<?php
public class User {
public $userid;
public $username;
private $password;
public class UserProfile {
// Some code here
}
private class UserHistory {
// Some code here
}
}
?>
这可能在PHP？我怎样才能实现它？
UPDATE
如果不可能,未来的PHP版本是否可能支持嵌套类？
Tiv*_*vie 127
嵌套类与其他类的关系与外部类略有不同.以Java为例:
非静态嵌套类可以访问封闭类的其他成员,即使它们被声明为私有.此外,非静态嵌套类需要实例化父类的实例.
OuterClass outerObj = new OuterClass(arguments);
outerObj.InnerClass innerObj = outerObj.new InnerClass(arguments);
使用它们有几个令人信服的理由:
如果一个类只对另一个类有用,那么将它关联并嵌入该类并将两者保持在一起是合乎逻辑的.
考虑两个顶级类A和B,其中B需要访问A的成员,否则这些成员将被声明为私有.通过将类B隐藏在类A中,可以将A的成员声明为私有,并且B可以访问它们.另外,B本身可以隐藏在外面.
嵌套类通常与它的父类相关,并共同形成一个"包"
在没有嵌套类的PHP中,您可以有类似的行为.
如果你想要实现的只是结构/组织,就像Package.OuterClass.InnerClass一样,PHP命名空间可能会受到影响.您甚至可以在同一个文件中声明多个名称空间(尽管由于标准的自动加载功能,这可能并不可取).
namespace;
class OuterClass {}
namespace OuterClass;
class InnerClass {}
如果您希望模拟其他特征,例如成员可见性,则需要花费更多精力.
namespace {
class Package {
/* protect constructor so that objects can't be instantiated from outside
* Since all classes inherit from Package class, they can instantiate eachother
* simulating protected InnerClasses
*/
protected function __construct() {}
/* This magic method is called everytime an inaccessible method is called
* (either by visibility contrains or it doesn't exist)
* Here we are simulating shared protected methods across "package" classes
* This method is inherited by all child classes of Package
*/
public function __call($method, $args) {
//class name
$class = get_class($this);
/* we check if a method exists, if not we throw an exception
* similar to the default error
*/
if (method_exists($this, $method)) {
/* The method exists so now we want to know if the
* caller is a child of our Package class. If not we throw an exception
* Note: This is a kind of a dirty way of finding out who's
* calling the method by using debug_backtrace and reflection
*/
$trace = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, 3);
if (isset($trace[2])) {
$ref = new ReflectionClass($trace[2]['class']);
if ($ref->isSubclassOf(__CLASS__)) {
return $this->$method($args);
}
}
throw new \Exception("Call to private method $class::$method()");
} else {
throw new \Exception("Call to undefined method $class::$method()");
}
}
}
}
namespace Package {
class MyParent extends \Package {
public $publicChild;
protected $protectedChild;
public function __construct() {
//instantiate public child inside parent
$this->publicChild = new \Package\MyParent\PublicChild();
//instantiate protected child inside parent
$this->protectedChild = new \Package\MyParent\ProtectedChild();
}
public function test() {
echo "Call from parent -> ";
$this->publicChild->protectedMethod();
$this->protectedChild->protectedMethod();
echo "<br>Siblings<br>";
$this->publicChild->callSibling($this->protectedChild);
}
}
}
namespace Package\MyParent
{
class PublicChild extends \Package {
//Makes the constructor public, hence callable from outside
public function __construct() {}
protected function protectedMethod() {
echo "I'm ".get_class($this)." protected method<br>";
}
protected function callSibling($sibling) {
echo "Call from " . get_class($this) . " -> ";
$sibling->protectedMethod();
}
}
class ProtectedChild extends \Package {
protected function protectedMethod() {
echo "I'm ".get_class($this)." protected method<br>";
}
protected function callSibling($sibling) {
echo "Call from " . get_class($this) . " -> ";
$sibling->protectedMethod();
}
}
}
$parent = new Package\MyParent();
$parent->test();
$pubChild = new Package\MyParent\PublicChild();//create new public child (possible)
$protChild = new Package\MyParent\ProtectedChild(); //create new protected child (ERROR)
输出:
Call from parent -> I'm Package protected method
I'm Package protected method
Siblings
Call from Package -> I'm Package protected method
Fatal error: Call to protected Package::__construct() from invalid context
我真的不认为尝试在PHP中模拟innerClasses是一个好主意.我认为代码不那么干净和可读.此外,可能还有其他方法可以使用完善的模式来实现类似的结果,例如Observer,Decorator ou COmposition Pattern.有时,即使是简单的继承就足够了.
Fab*_*ler 19
带有public/ protected/ privateaccessibility的真正嵌套类在2013年被提议用于PHP 5.6作为RFC但没有成功(没有投票,自2013年以来没有更新 - 截至2016/12/29):
https://wiki.php.net/rfc/nested_classes
class foo {
public class bar {
}
}
至少,匿名类使其成为PHP 7
https://wiki.php.net/rfc/anonymous_classes
从这个RFC页面:
未来范围
这个补丁所做的更改意味着命名嵌套类更容易实现(稍微有点).
因此,我们可能会在未来的某个版本中获得嵌套类,但尚未确定.
Sum*_*and 12
你不能用PHP做到这一点.但是,有一些功能方法可以实现这一目标.
有关更多详细信息,请查看以下帖子: 如何执行PHP嵌套类或嵌套方法？
这种实现方式称为流畅的界面:http://en.wikipedia.org/wiki/Fluent_interface
根据 Xenon 对 An?l Özselgin 的回答的评论，匿名类已在 PHP 7.0 中实现，这与您现在所了解的嵌套类非常接近。以下是相关的 RFC：
原始帖子的示例，这就是您的代码的样子：
<?php
public class User {
public $userid;
public $username;
private $password;
public $profile;
public $history;
public function __construct() {
$this->profile = new class {
// Some code here for user profile
}
$this->history = new class {
// Some code here for user history
}
}
}
?>
但是，这带有一个非常讨厌的警告。如果您使用 PHPStorm 或 NetBeans 等 IDE，然后将这样的方法添加到User类中：
public function foo() {
$this->profile->...
}
...再见自动完成。即使您使用如下模式编码接口（SOLID 中的 I）也是如此：
<?php
public class User {
public $profile;
public function __construct() {
$this->profile = new class implements UserProfileInterface {
// Some code here for user profile
}
}
}
?>
除非您唯一的调用$this->profile来自__construct()方法（或$this->profile定义的任何方法），否则您将不会获得任何类型的提示。您的属性本质上是“隐藏”到您的 IDE 中的，如果您依赖 IDE 进行自动完成、代码异味嗅探和重构，这将使您的生活变得非常艰难。
从 PHP 5.4 版开始，您可以通过反射强制创建具有私有构造函数的对象。它可用于模拟 Java 嵌套类。示例代码：
class OuterClass {
private $name;
public function __construct($name) {
$this->name = $name;
}
public function getName() {
return $this->name;
}
public function forkInnerObject($name) {
$class = new ReflectionClass('InnerClass');
$constructor = $class->getConstructor();
$constructor->setAccessible(true);
$innerObject = $class->newInstanceWithoutConstructor(); // This method appeared in PHP 5.4
$constructor->invoke($innerObject, $this, $name);
return $innerObject;
}
}
class InnerClass {
private $parentObject;
private $name;
private function __construct(OuterClass $parentObject, $name) {
$this->parentObject = $parentObject;
$this->name = $name;
}
public function getName() {
return $this->name;
}
public function getParent() {
return $this->parentObject;
}
}
$outerObject = new OuterClass('This is an outer object');
//$innerObject = new InnerClass($outerObject, 'You cannot do it');
$innerObject = $outerObject->forkInnerObject('This is an inner object');
echo $innerObject->getName() . "\n";
echo $innerObject->getParent()->getName() . "\n";