[wp-hackers] Modify get_pages() behavior trough filter

[Filippo Toso]

Hi,

I'm trying to modify the behavior of the get_pages() function from a plugin.

I would like to add a child_of parameter to get_pages() when it is invoked
without the child_of or include parameters.

At the beginning I have tough I can solve this issue using a filter like the
following:

function get_pages_filter($result, $r) {
	if ((!isset($r['child_of']) || empty($r['child_of'])) &&
		(!isset($r['include']) || empty($r['include']))) {
		$r['child_of'] = 5; // this is just an example
		return get_pages($r);
	}
	return $result;
}

I have used the same code for get_categories and get_bookmarks filters and
they worked like a charm, but the get_pages() function behaves differently. 

After applying the get_pages filter, the $pages array is passed to the
get_page_children() function that "strips out" any page that hasn't the
right post_parent value.

The only solution I have been able to find is to add a new filter named
pre_get_pages at the beginning of the get_pages() function just before the
extract($r); command:

$r = apply_filters('pre_get_pages', $r);

In this way it's possible to manipulate the get_pages parameter before they
are used.

Following the same logic, it can be useful to add a post_get_pages filter at
the end of the get_pages() function (don't know if it has to be inserted
before or after the wp_cache_set() call):

$pages = apply_filters('post_get_pages', $pages, $r);

I will appreciate any any idea to avoid the modification of the get_pages()
code.

Sincerely,
Filippo Toso