<?php
function sum(...$numbers) {
 $acc = 0;
 foreach ($numbers as $n) {
  $acc += $n;
 }
 return $acc;
}
echo sum(1, 2, 3, 4);
?>

<?php
function add($a, $b) {
 return $a + $b;
}
echo add(...[1, 2])
?>

Route::get('user/{id}', 'UsersController@filter');
//路由对应的方法
public function filter($id)
{
 # code...
}

Route::get('user/{id}/{name}', 'UsersController@filter');
//路由对应的方法
public function filter($id, $name)
{
 # code...
}

// */vendor/laravel/framework/src/Illuminate/Routing/ControllerDispatcher.php
/**
 * Dispatch a request to a given controller and method.
 *
 * @param \Illuminate\Routing\Route $route
 * @param mixed $controller
 * @param string $method
 * @return mixed
 */
public function dispatch(Route $route, $controller, $method)
{
 $parameters = $this->resolveClassMethodDependencies(
  $route->parametersWithoutNulls(), $controller, $method
 );
 if (method_exists($controller, 'callAction')) {
  return $controller->callAction($method, $parameters);
 }
 return $controller->{$method}(...array_values($parameters));
}