A recursive sorta-version of wp_parse_args()

gistfile1.php

<?php

	/**
	 * Recursive argument parsing
	 *
	 * This acts like a multi-dimensional version of wp_parse_args() (minus
	 * the querystring parsing - you must pass arrays).
	 *
	 * Values from $a override those from $b; keys in $b that don't exist
	 * in $a are passed through.
	 *
	 * This is different from array_merge_recursive(), both because of the
	 * order of preference ($a overrides $b) and because of the fact that
	 * array_merge_recursive() combines arrays deep in the tree, rather
	 * than overwriting the b array with the a array.
	 *
	 * The implementation of this function is specific to the needs of
	 * BP_Group_Extension, where we know that arrays will always be
	 * associative, and that an argument under a given key in one array
	 * will be matched by a value of identical depth in the other one. The
	 * function is NOT designed for general use, and will probably result
	 * in unexpected results when used with data in the wild. See, eg,
	 * http://core.trac.wordpress.org/ticket/19888
	 *
	 * @since BuddyPress (1.8)
	 * @arg array $a
	 * @arg array $b
	 * @return array
	 */
	public static function parse_args_r( &$a, $b ) {
		$a = (array) $a;
		$b = (array) $b;
		$r = $b;

		foreach ( $a as $k => &$v ) {
			if ( is_array( $v ) && isset( $r[ $k ] ) ) {
				$r[ $k ] = self::parse_args_r( $v, $r[ $k ] );
			} else {
				$r[ $k ] = $v;
			}
		}

		return $r;
	}