Create is_page_or_child() Template Tag

[FireMotion]

Description
Recursively determine if a page or one of its child pages is currently displayed.

Proposed usage
is_current('42')

Returns true when Page 42 or one of its child pages is being displayed.

It would also help to include the "exclude" parameter.

Purpose
To create code for dynamic/collapsable menu's more easily.

Current workaround
Part of the variable currently equals:

strpos(wp_list_pages('echo=0&exclude='.$exclude.'&child_of='.$page_id), 'current_page_item') !== FALSE

But this only includes the child pages, not the page with $page_id itself.

You can already do is_page(42). Not sure if that works for child pages.

Maybe it should be something like is_page_or_child('42'):

Example: A menu with a lot of subpages, but only the current pages' navigation should be expanded, the others should be collapsed:
Wordpress

• About

--- Who

• Download

--- UpgradeGuide
--- DownloadGuide

---

• Tutorial

Forum

• Support
• Development

Let's say that "UpgradeGuide" is the current page. Therefore, it should look like this:
Wordpress

• About [Collapsed]
• Download [Expanded]

--- UpgradeGuide
--- DownloadGuide [Collapsed]

• Tutorial

Forum [Collapsed]

1) First get all the top navigation items for the pages (wp_list_pages('depth=1')).
2) Explode that list as an array, then for each item, determine if it should display the submenu items.

How would one easily determine if it should retrieve (wp_list_pages) all the subnavigation/listpages for "Download" or not? Because is_page('Download') returns false, as the actual page is "UpgradeGuide," not "Download."

Menu's in previous post should read:

Wordpress
- About
--- Who
- Download
--- UpgradeGuide
--- DownloadGuide
----- DownloadTroubleshooting
- Tutorial
Forum
- Support
- Development

And:

Wordpress
- About ''[Collapsed]''
- Download ''[Expanded]''
--- UpgradeGuide
--- DownloadGuide ''[Collapsed]''
- Tutorial
Forum ''[Collapsed]''

Done that. (I'm missing that part too).

see: ​http://trac.wordpress.org/ticket/1277