is_child()

[youngmicroserf]

Is there any reason why there is no native is_child(direct,in_tree) function for hierarchical structures in WP (like pages, categories, custom hierarchical taxonomies)? There's a (partly) working plugin available at

​http://2pt3.com/post/wordpress-plugins/

but I think this amounts to a core functionality, particularly for people using WP as a hierarchical CMS.

Bumping this up.

Unfortunately this has missed the boat for 3.0 as we're in a feature freeze.

I'm not setting this to 3.1 due to there not being a patch. If someone provides a patch, it may be in 3.1.

...And there i go setting it to 3.1 anyway... I'll leave it in 3.1 for now.

Related: #12443

If we get #12443 in, is_child() would be as simple as:

function is_child( $child, $parent, $object_type ) {
    return in_array( $parent, get_ancestors( $child, $object_type ) );
}

There's no need to have both is_descendant and is_ancestor, right?

No, they're the same, except the parameter order would be different.

I was about to make cat_is_ancestor_of() use get_ancestors().

Then I realized that cat_is_ancestor_of(), as it is now, will stop once it finds a match, whereas get_ancestors() wouldn't.

So yeah, disregard comment:8

Still just needs a patch.

That said, we should probably avoid is_* as it isn't a conditional tag.

has_child_relationship()

Documenting return type