Question

I have a callback function for another function that loops through the comments of an article in my blog. I now tried to switch to “threaded/nested” comments and therefore extended the callback function. So far everything works, but i can’t get rid of the feeling, that i didn’t write it according to best php-practice (and performance).

I use a css framework and have to do some math for the .span-xy classes i assign to the single comments. I start with an input value from a global constant and output eg. span-12 for a parent comment. Then i have to reduce/rise the value per +/- (int) 1 for every level of nesting. So i came to building arrays, counting them, iterating through and building temp arrays for every comment.

Question:
Is there an easier way to get around this?

<!-- This is the final html mark-up output: List of comments (threaded/nested) -->
<ul>
    <li id="1" class="push-<?php echo $push; ?> span-<?php echo $span; ?>">comment - parent</li>
    <li id="2">comment - child of #1
        <ul class="children">
            <li id="3">comment - child of #2
            <li id="4">comment - child of #2
                <ul class="children">
                    <li id="5">comment - child of #4</li>
                </ul>
            <li id="6">comment - child of #2</li>
        </ul>
        <li id="7">comment - child of #2
            <ul class="children">
                <li id="8">comment - child of #7</li>
                <li id="9">comment - child of #7</li>
            </ul>
        </li>
    </li>
</ul>

<?php
// This is my callback function
function comment_list_cb( $comment, $args, $depth )
{
    // retrieve the data from the globals or make them available
    $GLOBALS['comment'] = $comment;
    global $post;

    static $width = MY_GLOBAL_WIDTH_CONSTANT;
    static $ancestors = null;

    // is Child/Parent comment
    $parent = (int) $comment->comment_parent; // retrieve the ID of the parent

    $is_child = false;
    if ( $parent > (int) 0 ) // if we got a parent
    {
        $is_child = true;

        if ( ! (array) $ancestors )
            $ancestors = array();

        if ( ! array_key_exists( $parent, $ancestors ) )
        {
            $ancestors[$parent] = get_comment_ID();
        }
        else 
        {
            foreach ( $ancestors as $parent_id => $child_id )
            {
                if ( $parent_id == $parent )
                {
                    $ancestors_temp[$parent_id] = $child_id;
                    break;
                }

                $ancestors_temp[$parent_id] = $child_id;
            }
            $ancestors = $ancestors_temp;
        }

        $parent_counter = count( $ancestors );
        $span = $width - (int) $parent_counter;
    }
    else 
    {
        $ancestors = $parent_counter = null;
        $span = MY_GLOBAL_WIDTH_CONSTANT;
    }

$span_txt = $span - (int) 2; // reduce per `2` because of the span-2 class at the avatar element

    // now: build the classes
    $push = $parent_counter != (int) 0 ? 'push-1' : '';
    $child = $is_child === true ? ' child ' : '';
    $list = comment_class( 'span-'.$span.' '.$push.' append-bottom last hreview comment-'.get_comment_ID().' '.$microid, get_comment_ID(), $post->ID, false );

    ?>
    <!-- build the comment -->
    <li <?php echo $list; ?>>
        <div id="<?php get_comment_ID(); ?>">
            <span class="comment-avatar span-2"><!-- display avatar img - width is span-2 --></span>
            <span class="comment-meta span-<?php echo $span_txt; ?> last"><!-- display meta data like timestamp, etc. --></span>
            <span class="comment-text span-<?php echo $span_txt; ?> last"><!-- display message --></span>
        </div>
    </li>
    <?php
}

Answer 1

Just some general comments after a quick scan. It deals with the coding, irrespective of functionality.

$GLOBALS['comment'] = $comment;

Why are you putting this in global scope? This can overwrite an existing global variable. Passing by reference may be more appropriate here.

static $width = MY_GLOBAL_WIDTH_CONSTANT;

Why is this static? Value is never changed so there’s no need to retain.

if ( $parent > (int) 0 )
[...]
$span_txt = $span - (int) 2;
[...]
$push = $parent_counter != (int) 0 ? 'push-1' : '';

No need to cast int literal to int. If you want int comparison, it’s the variable you should be casting.

if ( ! (array) $ancestors )
    $ancestors = array();

If empty array, make empty array? Just do !isset($ancestors)