PHP魔法方法是自動觸發(fā)的內置函數(shù)，用於響應對象交互中的特定行為。它們以雙下劃線開頭，並在特定場景下自動執(zhí)行；__c??onstruct()在對象創(chuàng)建時調用，用於初始化操作；__destruct()在對象銷毀前調用，適合清理資源；__get()與__set()處理不可訪問屬性的動態(tài)訪問；__call()和__callStatic()分別用於處理未定義的實例方法和靜態(tài)方法調用；其他如__sleep()、__wakeup()、__toString()、__invoke()則分別在序列化、反序列化、對象轉字符串及對像作為函數(shù)調用時觸發(fā)，提升類靈活性的同時需注意適度使用以避免代碼可讀性下降。

PHP magic methods are special built-in functions that get triggered automatically when certain actions happen in your code. They're called "magic" because they don't need to be explicitly called — they run behind the scenes based on how you interact with your objects.

These methods always start with double underscores ( __ ), and there are several of them, each serving a specific purpose. Here's a breakdown of some of the most commonly used ones and when they're invoked.

__construct() – When an object is created

This is probably the most familiar one. It runs automatically when you create a new instance of a class.

 class User {
    public function __construct() {
        echo "User created";
    }
}

$user = new User(); // Outputs: User created

You can pass arguments to it when instantiating the object, which makes it useful for setting up initial values or dependencies.

__destruct() – When an object is destroyed

This method is called right before an object is destroyed, usually when the script ends or when the object goes out of scope.

 class Logger {
    public function __destruct() {
        echo "Logger closed";
    }
}

$logger = new Logger();
// Outputs: Logger closed (after script finishes)

It's often used for cleanup tasks like closing database connections or file handles.

__get() and __set() – Accessing inaccessible properties

If you try to access or assign a value to a property that isn't accessible (like being private or not defined at all), PHP will look for these methods.

 class Person {
    private $data = [];

    public function __set($name, $value) {
        $this->data[$name] = $value;
    }

    public function __get($name) {
        return $this->data[$name] ?? null;
    }
}

$p = new Person();
$p->name = "Alice";
echo $p->name; // Outputs: Alice

These are super handy for implementing dynamic properties or lazy loading behavior.

__call() and __callStatic() – Calling undefined methods

When you try to call a method that doesn't exist or isn't visible, PHP checks if __call() is defined. Similarly, __callStatic() works for static calls.

 class Math {
    public function __call($method, $args) {
        if (strpos($method, 'power') === 0) {
            return pow($args[0], $args[1]);
        }
    }
}

$m = new Math();
echo $m->powerTwo(2, 3); // Returns 8

This can be used to implement flexible APIs or fallback behaviors.

Other useful ones you might see:

• __sleep() – Before serializing an object
• __wakeup() – After unserializing
• __toString() – When the object is treated as a string (eg, in echo )
• __invoke() – When the object is called like a function

They all help make your classes more flexible and expressive without having to write boilerplate code.

Not every class needs magic methods, but knowing how and when they're triggered gives you more control over object behavior. Use them thoughtfully — they're powerful, but can also make code harder to follow if overused.

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