How to change the function call?

Question

PHP

Hello everyone, there is a function that displays a value from an IPB 3.4.x array

public function getUser($param)
  {
    $IPSMember = new IPS();
    $IPSMember->init();
    $member = $IPSMember->getMember();
    return $member[$param];
  }

I call it like this
$member->getUser('member_id');
I need to do the same but in IPS 4.x
at the moment it is called like this

$member = \IPS\Member::loggedIn();
echo $member->member_id;

The question is how to extract an element from an array as in IPB 3.4.x?
i.e

public function getUser($param)
  {
    $member = \IPS\Member::loggedIn();
return $member->[$param];//Пример
  }

Answer 1

public function getUser($param)
{
    return \IPS\Member::loggedIn()->{$param};
}

Answer 2

$member->{$param};

Answer 3

Or more concisely:
call_user_func(array($member, $param))