Base_url as a default value in a custom Config file

PHP Code:

namespace App\Config;

use CodeIgniter\Config\BaseConfig;

class MyConfig extends BaseConfig
{
    public $myTargetLink  = base_url() . '/path/to/link';

} 


Hello.

I am wondering how I can access the base_url in a Config file.

Doing this give me an error "Constant expression contains invalid operations"

Is getting the base_url() possible as a default value in a Config file?

Thanks for your time.

Max