回答

两种方式

1、正则匹配修改class加载机制

spl_autoload_register(function($class) {
    $file = __DIR__ . "/classes/{$class}.php";
    if (!file_exists($file)) return;

    $code = file_get_contents($file);

    // 简单插入 extends 语句（不推荐用于生产）
    $code = preg_replace('/class\s+' . preg_quote($class) . '\s*{/', "class {$class} extends ParentClass {", $code, 1);

    eval('?>' . $code);
});

<?php
class ParentClass {
    public function sayHello() {
        echo "Hello from ParentClass\n";
    }
}

class ChildClass {
    private $parent;

    public function __construct(ParentClass $parent) {
        $this->parent = $parent;
    }

    public function sayHi() {
        echo "Hi from ChildClass\n";
    }

    public function __call($method, $args) {
        if (method_exists($this->parent, $method)) {
            return $this->parent->$method(...$args);
        }
        throw new \BadMethodCallException("Method {$method} not found");
    }
}

// 使用
$parent = new ParentClass();
$child = new ChildClass($parent);
$child->sayHi();      // 输出: Hi from ChildClass
$child->sayHello();   // 输出: Hello from ParentClass