PHP

Didn't work:

<?php
  // Remove the current node ID, if present.  This looks crazy but it's fast,
  // see http://lixlpixel.org/php-benchmarks/remove-array-items-by-value
  if ($nids) {
    $nids = explode(',', str_replace($current_nid . ',', '', join(',', $nids)));
  }
?>

Worked:

Can't be as complicated as these people make it out to be?
http://dev-tips.com/featured/remove-an-item-from-an-array-by-value

One of Agaric's approaches, below. This foreach allows one to unset just one validation function associated with a form (and adds another one below) without replacing or overriding any other validation callbacks that might be associated with the form (by the initial or other modules).

I love it when PHP has the logically named function. To get the lowest of two or more variables, min($var1, $var2)

Resolution

There is a built-in PHP function to get the directory portion of a file path from a string (lopping off the filename itself).

http://us3.php.net/dirname

Resolution

Right there in the examples for the php function preg_replace was how to strip whitespace from a string:

<?php
$str = preg_replace('/\s\s+/', ' ', $str);
?>

Ereg replace looks prettier:

<?php
$string = trim(ereg_replace(' +', ' ', $string));
?>

However, Agaric has read in several places that preg_replace tends to be faster.

Resolution

Explode has a limit parameter. Happy day at Agaric!

This code below was written offline when I was merely hoping that explode could be limited to splitting on its first parameter only the first time said parameter is seen:

Solution

(From rnreekez in the comments, syntax modified to conform to Drupal's more verbose coding standards.)

Technically you want your switch statement to process for all things TRUE.