__callStatic():从静态上下文实例化对象吗? [英] __callStatic(): instantiating objects from static context?

问题描述

我对PHP中的静态"和动态"函数与对象如何协同工作感到困惑，尤其是在__callStatic()方面.

I am confused about how "static" and "dynamic" functions and objects in PHP work together especially with regards to __callStatic().

__callStatic()的工作方式:

您可以有一个普通的类MyClass，在该类中您可以 放置一个名为__callStatic()的静态函数，该函数仅被调用 当MyClass没有想要的名称的静态函数时.

You can have a normal class MyClass, where within the class you can put a static function called __callStatic(), which gets called only when MyClass doesn't have a static function by the name you want.

即我叫MyClass::newFunction();

newFunction()被静态调用，但MyClass不被静态调用 宣布.因此，然后__callStatic()被调用并 在里面你可以说

newFunction() is called statically but MyClass does not have it declared. So, then __callStatic() gets called and inside you can say

$myObject=new SomeOtherClass();
$myObject->newFunction();

它将调用您想要的函数，但在其他对象上.

which calls the function you wanted but on some other object.

简短版本:

换句话说，__callStatic()做到了:

In other words, __callStatic() does this:

MyClass::newFunction();

其中隐藏了这个内容:

(new SomeOtherClass())->newFunction();

现在说些什么?看起来像代码从类中调用静态函数的代码，原来是从其他某个类中调用该函数，并通过实例化而不是静态地调用它.

Say what now? What looks like code calling a static function from a class, turns out to be calling that function from some other class and calling it via instantiation, and not statically.

请解释一下！

为什么要做?您可以在其他地方(例如C ++或Java)做类似的事情吗?我正在寻找短&对语言中的静态和动态函数的简要而有启发性的解释，在这种情况下，是对__语言构造的总体了解还是__callStatic()violates或conforms.还是完全是一种新的语言结构.

Why was it done? Can you do anything like this elsewhere, like C++ or Java? I am looking for short & concise, but informative explanation on static and dynamic functions in languages, and in this case whether __callStatic() violates or conforms to the big picture of Language constructs. Or is it a new language construct entirely.

推荐答案

__callStatic()为开发人员提供了对static方法调用做出反应的可能性，即使该方法不存在或从类外部(protected)可以访问.这对于动态的通用代码生成很有用.

__callStatic() provides developers with possibility to react on static method calls even if that methods don't exist or aren't accessible from outside of the class ( being protected). This is useful for dynamic, generic code generation.

示例:您拥有此类:

class Test {

    protected static function myProtected($test) {
        var_dump(__METHOD__, $test);
    }

    public static function __callStatic($method, $args) {
        switch($method) {
            case 'foo' :
                echo 'You have called foo()';
                var_dump($args);
                break;

            case 'helloWorld':
                echo 'Hello ' . $args[0];
                break;

            case 'myProtected':
                return call_user_func_array(
                    array(get_called_class(), 'myProtected'),
                    $args
                );
                break;                      
        }

    }

}

尝试致电:

// these ones does not *really* exist
Test::foo('bar');
Test::helloWorld('hek2mgl');

// this one wouldn't be accessible
Test::myProtected('foo');

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