class MyObject extends DataObject
{
    private static $has_one = [
        'Relation' => 'SomeObject',
        'AFallBack' => 'SomeObject',
    ];

    public function SomeFunction()
    {
        return 'Some text';
    }

    public function getValue()
    {
        return $this->sreg('Lorem ipsum {$Relation.Title|AFallBack.Title|Fall back text} {$SomeFunction}');
    }
}