// helpers.php
if (!function_exists('get_current_router_bind')) {
    function get_current_router_bind_key() {
        dd(key(array_reverse(last(last(debug_backtrace(0)[2])))));
    }
}

// UserController
// update(Request $request, User get_current_router_bind_key())
public function update(Request $request, User $user)
{
    get_current_router_bind_key();
    $this->authorize('update', $user);

    $user->update(array_only($request->all(), $user->getFillable()));

    return $this->success($user);
}