WordPress at a glance
filter is not described

comment_class filter-hook . WP 2.7.0

Filters the returned CSS classes for the current comment.

Usage

add_filter( 'comment_class', 'filter_function_name_4268', 10, 5 );
function filter_function_name_4268( $classes, $class, $comment_id, $comment, $post_id ){
	// filter...

	return $classes;
}
$classes(array)
An array of comment classes.
$class(string)
A comma-separated list of additional classes added to the list.
$comment_id(int)
The comment id.
$comment(WP_Comment)
The comment object.
$post_id(int/WP_Post)
The post ID or WP_Post object.

Where the hook is called

get_comment_class()
comment_class
wp-includes/comment-template.php 525
return apply_filters( 'comment_class', $classes, $class, $comment->comment_ID, $comment, $post_id );

Where the hook is used (in WP core)

Does not used.