直接调用闭包分配给对象属性 [英] Calling closure assigned to object property directly

问题描述

我想能够调用一个闭包，直接分配给一个对象的属性，而不将闭包重新分配给一个变量，然后调用它。这是可能吗？

I would like to be able to call a closure that I assign to an object's property directly without reassigning the closure to a variable and then calling it. Is this possible?

下面的代码不工作，并导致致命错误：调用未定义的方法stdClass :: callback c $ c>。

The code below doesn't work and causes Fatal error: Call to undefined method stdClass::callback().

$obj = new stdClass();
$obj->callback = function() {
    print "HelloWorld!";
};
$obj->callback();

推荐答案

As of PHP7, you can do

$obj = new StdClass;
$obj->fn = function($arg) { return "Hello $arg"; };
echo ($obj->fn)('World');

或使用 Closure :: call（），但不能在 StdClass 上工作。

or use Closure::call(), though that doesn't work on a StdClass.

在PHP7之前，您必须实现神奇的 __ call 方法来拦截调用并调用回调这是不可能的 StdClass 当然，因为你不能添加 __调用方法）

Before PHP7, you'd have to implement the magic __call method to intercept the call and invoke the callback (which is not possible for StdClass of course, because you cannot add the __call method)

class Foo
{
    public function __call($method, $args)
    {
        if(is_callable(array($this, $method))) {
            return call_user_func_array($this->$method, $args);
        }
        // else throw exception
    }
}

$foo = new Foo;
$foo->cb = function($who) { return "Hello $who"; };
echo $foo->cb('World');

请注意，您不能执行

return call_user_func_array(array($this, $method), $args);

在无限循环中触发 __ call 。

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