如何调用PHP中存储在Class属性中的function

Question

Hi I'm very new at PHP and wanted to know if you can store a function in a Class Property and then call it later.

class Route
{
  public $handler;
  //$handler is a reference to a function that I want to store and call later 
  function __construct($handler) 
  {
    $this->handler = $handler;
    //or maybe something like
    //$this->handler = fn () => $handler();

    //this works fine
    $handler();

    /*I get why this does not work since $handler is not a 
    method of this class but how would I store a function 
    and be able to call it later in a different context?*/
    $this->handler();
  }
}

How would I do something like this?

function foo()
{
  echo "success";
}

$route = new Route('foo');
$route->$handler();

Answer 1

Use brackets when calling your property stored callable:

class Route
{
  public $handler;

  public function __construct(callable $handler) {
    $this->handler = $handler;
  }
}

$handler = static fn() => var_dump('Works');
$obj = new Route($handler);

($obj->handler)();

then

$ php test.php
string(5) "Works"

PS: I recommend to always use type hints.

Answer 2

I hope the code below helps.

class Route
{
  public $handler;
  function __construct($handler)
  {
    $this->handler = $handler;
  }
}

function foo()
{
  echo "success";
}

$route = new Route('foo');

/* There is problem to call a function that is a class property. */
/* You may use a temporary variable. */
$function = $route->handler;
$function();