#2593: The walk_tree family should be a class
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Id: 2593 | Status: new
Component: Administration | Modified: Sat Mar 25 15:49:31 2006
Severity: normal | Milestone:
Priority: normal | Version: 1.2
Owner: anonymous | Reporter: davidhouse
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Comment (by davidhouse):
That was a crap explanation. Lets go again.
{{{walk_tree()}}} is a nice new generic function that got added to be the
core a few weeks ago. It's a kind of generic pretty-printer for tree-like
structures. For example, we used to have {{{list_cats()}}} and
{{{wp_list_pages()}}}, both of which printed a hierarchial structure out
(the category list for the former, the page list for the latter).
{{{walk_tree()}}} generalises this by allowing you to pass in some
callbacks that will get called when starting a new element, finishing an
element, or ascending or descending a level.
Callbacks are ugly when abused like this, so this is how my class does it:
suppose you want to print some hierarchial tree. Create a new class which
extends {{{Walker}}} and defines the following methods:
* {{{start_el()}}}
* {{{end_el()}}}
* {{{start_lvl()}}}
* {{{end_lvl()}}}
The names should be fairly self-explanatory. You'll also need to define
$dbfields, an associative array:
* {{{$dbfields['parent']}}} should be the DB field which is the parent of
any given record. This is {{{post_parent}}} for posts and
{{{category_parent}}} for cats.
* {{{$dbfields['id']}}} is the same but for the ID. E.g. {{{ID}}} for
posts and {{{cat_ID}}} for cats.
Once that's done, create an instance and call {{{$instance->walk()}}}
passing in the elements you want to print (in object form), and the
maximum depth (or -1 to just print flat, no hierarchy). Any extra
parameters will get passed to your callbacks.
There are examples in the code.
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Ticket URL: <http://trac.wordpress.org/ticket/2593>
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