Cycling between strings, a novel implementation
When outputting a table, a common task is to alternate the row colours to give a zebra effect - an effect commonly said (though debated) to increase readability.
A novel solution to this problem involves using PHP5’s new __toString method: introducing Cycle.
<?php
/**
* A simple cycle class for alternating between strings.
*
* @author Aidan Lister <aidan@php.net>
* @version 1.0.1
* @link http://aidanlister.com/2004/04/cycling-between-strings-a-novel-implementation/
*/
class Cycle
{
/**
* Array of strings to be cycled
*
* @var array
*/
private $_args;
/**
* The current position in the stack
*
* @var array
*/
private $_key;
/**
* Constructor
*
* @param overloader Strings to be cycled through
*/
function __construct()
{
$this->_args = func_get_args();
$this->_key = -1;
}
/**
* Convert to a string
*
* @return string The next string in the stack
*/
function __toString()
{
return (string) isset($this->_args[$this->_key += 1]) ?
$this->_args[$this->_key] :
$this->_args[$this->_key = 0] ;
}
}
?>Thus with minimal effort, simply echoing the string will seemingly magically alternate between the specified outputs. An example:
<?php
require_once 'Cycle.php';
$rowclass = new Cycle('odd', 'even');
for ($i = 0; $i < 5; $i++) {
echo "<td class=$rowclass>\n";
}
?>This would output: