class b extends a {
}
$b = new b($input) extends a;
我的目标是在管理页面和公共页面使用同一个模块，但实现方式不同。我知道可以创建两个具有相同名称的父类，然后只在管理页面或公共页面中包含其中一个。但我的问题是，在PHP中是否可以动态地实现这一点？
不行，除非使用类似RunKit这样的扩展程序。
你可以考虑另一种方法。如果你想让B承担A的功能，也许下面的方法可以提供一种“混入”方法。总体思路是，B不是A的子级，而是将任务委托给A。
<?php
class MixMeIn
{
public $favouriteNumber = 7;
public function sayHi() {
echo "Hello\n";
}
}
class BoringClass
{
private $mixins = array();
public function mixin($object)
{
$this->mixins[] = $object;
}
public function doNothing() {
echo "Zzz\n";
}
public function __call($method, $args)
{
foreach ($this->mixins as $mixin)
{
if (method_exists($mixin, $method))
{
return call_user_func_array(array($mixin, $method), $args);
}
}
throw new Exception(__CLASS__ + " has no method " + $method);
}
public function __get($attr)
{
foreach ($this->mixins as $mixin)
{
if (property_exists($mixin, $attr))
{
return $mixin->$attr;
}
}
throw new Exception(__CLASS__ + " has no property " + $attr);
}
public function __set($attr, $value)
{
foreach ($this->mixins as $mixin)
{
if (property_exists($mixin, $attr))
{
return $mixin->$attr = $value;
}
}
throw new Exception(__CLASS__ + " has no property " + $attr);
}
}
// testing
$boring = new BoringClass();
$boring->doNothing();
try {
$boring->sayHi(); // not available :-(
}
catch (Exception $e) {
echo "sayHi didn't work: ", $e->getMessage(), "\n";
}
// now we mixin the fun stuff!
$boring->mixin(new MixMeIn());
$boring->sayHi(); // works! :-)
echo $boring->favouriteNumber;
或者，如果您熟悉JavaScript风格的继承并且不介意失去类型检查：
<? //PHP 5.4+
final class ExpandoLookalike {
//Allow callable properties to be executed
public function __call($name, $arguments) {
\call_user_func_array($this->$name, $arguments);
}
}
$newBaseModule = static function(){
$base = new ExpandoLookalike();
//Common base functions get assigned here.
$basePrivateVar = 42;
$base->commonFunction = static function($params1, $params2) use ($basePrivateVar){
echo "common function\n";
};
$base->comment = static function() use ($basePrivateVar){
echo "Doing base comment with $basePrivateVar\n";
};
return $base;
};
//Javascript-style extends
$newAdminModule = static function($param) use ($newBaseModule){
$base = $newBaseModule();
$privateVar = 5;
$base->adminProperty = 60;
$base->suspendSite = static function() use ($param, $privateVar){
echo 'Doing admin only function ';
echo "with $param, $privateVar\n";
};
return $base;
};
$newPublicModule = static function() use ($newBaseModule){
$base = $newBaseModule();
$privateVar = 3;
//Javascript-style overloading
$oldComment = $base->comment;
$base->comment = static function($data) use ($oldComment, $privateVar){
$oldComment();
echo 'Doing public function ';
echo "with $data\n";
};
return $base;
};
$baseModule = $newBaseModule();
$adminModule = $newAdminModule('P');
$publicModule = $newPublicModule();
$adminModule->suspendSite(); //echos 'Doing admin only function with P, 5'
echo "{$adminModule->adminProperty}\n"; //echos '60'
$publicModule->comment('com'); //echos 'Doing base comment with 42'
//'Doing public function with com'
?>
尽管关闭了Traits和Interfaces之门，但它打开了其他有趣的补偿之门：
<? //PHP 5.4+
$inheritAllTheThings = static function(){
$base = new ExpandoLookalike();
foreach(\func_get_args() as $object){
foreach($object as $key => $value){
//Properties from later objects overwrite properties from earlier ones.
$base->$key = $value;
}
}
return $base;
};
$allOfEm = $inheritAllTheThings(
$newPublicModule(),
$newAdminModule('Q'),
['anotherProp' => 69,]
);
$allOfEm->comment('f'); //echos 'Doing base comment with 42'
//Because AdminModule came after PublicModule, the function that echos 'f'
//from PublicModule was overridden by the function from AdminModule.
//Hence, order denotes resolutions for multiple inheritance collisions.
$allOfEm->suspendSite(); //echos 'Doing admin only function with Q, 5'
echo $allOfEm->anotherProp . "\n"; //echos '69'
?>
但是在对象创建时不能使用extends。 extends仅用于类定义，并定义哪个其他类是我们新类的“父类”。
是的，正如Cory所提到的那样，这个功能以前已经被请求过了。但在此之前，您可以创建一个解决方法。以下是我旧学校的技巧
创建两个不同的类，像这样：
class a {
}
class b {
public $object;
}
然后，也创建一个扩展版本
class bextendeda extends a {
}
class b {
public $object;
public function __contruct($extend = false) {
if($extend) $this -> object = new bextendeda();
else $this -> object = $this;
}
function __get($prop) {
return $this-> object -> $prop;
}
function __set($prop, $val) {
$this-> object -> $prop = $val;
}
function __call($name, $arguments)
{
return call_user_func_array(array($this -> object, $name), $arguments);
}
}
那么，就是这样啦，如果你想要扩展版，只需要这样做
$b = new b(true);
如果不是
$b = new b();
祝您愉快 :)
$extend为真，则它会像工厂一样运作。 - Starxnew b将始终导致类型为b的对象，你无法改变这一点。 - deceze->object 来做任何事情... :) - decezeextend扩展你的类吧，好吗？;) - deceze$a=(a)(new b($input));
这并不完全相同，但是类似。