如何定义一个仅在没有参数传递给构造函数时才能实例化的类？

Question

How can I define a class that can only be instantiated without parameters, and forbids instantiation when any parameters are passed to the constructor?

My goal is to enforce a certain set of classes that are supposed to be "simple" and be used as a template. As part of that, I don't want anything to be passed to the constructor during instantiation.

When anything is passed via constructor, I want things to fail (RunTime Error, Fatal Error, Static interpreter error check, etc)

class Template()
{
    ...
}

new Template(); // okay
new Template($anything); // must not work

Answer 1

Just raise an exception if anything was passed:

class Foo {
    public function __construct(...$args) {
        if (count($args) > 0) {
            throw new Exception('No arguments!');
        }
    }
}

Answer 2

class Test {

    public function __construct() {
        if (func_get_args()) {
            throw new Exception('No parameters are allowed.');  
        }
    }

}

try {
    $p = new Test('test');
} catch (Exception $e) {
    echo $e->getMessage();  
}