PHP绑定方法到另一个类

Question

Can i bind method of class Foo to class Bar? And why the code below throws a warning "Cannot bind method Foo::say() to object of class Bar"? With function instead of method code works fine.

P.S. I know about extending) it is not practical question, just want to know is it real to bind non-static method to another class

class Foo {

    public $text = 'Hello World!';

    public function say() {
        echo $this->text;
    }

}

class Bar {

    public $text = 'Bye World!';

    public function __call($name, $arguments) {
        $test = Closure::fromCallable(array(new Foo, 'say'));
        $res = Closure::bind($test, $this);
        return $res();
    }

}

$bar = new Bar();
$bar->say();

Code below works fine

 function say(){
    echo $this->text;
 }
 class Bar {

    public $text = 'Bye World!';

    public function __call($name, $arguments) {
        $test = Closure::fromCallable('say');
        $res = Closure::bind($test, $this);
        return $res();
    }

}

$bar = new Bar();
$bar->say();

Answer 1

This is currently not supported. If you want to bind a closure to a new object, it must not be a fake closure, or the new object must be compatible with the old one (source).

So, what is a fake closure: A fake closure is a closure created from Closure::fromCallable.

This means, you have two options to fix your problem:

1. Bar must be compatible with the type of Foo - so just make Bar extend from Foo, if possible.

2. Use unbound functions, like annonymous, static or functions outside of classes.