无限地寻找父母的对象

Question

I'm propably too tired but I've been wrestling with this one for a while. A container can either have a layout on its own, or it can have a parent somewhere up the hierarchy that has a layout. I need to find that layout no matter how far up the line it is.

The object $container has a property $parent which, if not null, references another $container object (same type).

I think this code has a problem in the while condition?

private function findInheritedLayout($container) {

    do {
        if ( $container->getLayoutTemplate() ) {
            return $container->getLayoutTemplate();
        }
        else {
            if ( $container->getParent() ) {
                $container = $container->getParent();
            }
            else {
                return null;
            }   
        }
    } while ( $container->getParent() ); //flawed? looks for a parent one step too far?
}

Answer 1

Your assumption is correct. The while condition checks if the current $container has a parent, without checking for a layout.

Try the following:

while (!$container->getLayoutTemplate() && $container->getParent()) {
    $container = $container->getParent();
}

$template = $container->getLayoutTemplate();
return $template ?: null;