This demonstrates howto cache a static methods output. I use this "lazy method" for example: when I don't want to make multiple calls to the database

example.cache_lib.php

<?php

Class Example_Lib {

	/**
	 * Internal cache helper
	 * Caches internal method results in memory
	 * 
	 * @param	string	$func	function to call
	 * @param	array	$args	arguments for the callback function
	 * @return	mixed 
	 */

	private static function _cache($func, $args)
	{
		// re-index numerically
		$args = array_values($args);
		
		// create a key lookup
		$key = sha1($func . serialize($args));

		// check for cached item
		if (isset(self::$CACHE[$key]))
		{
			return self::$CACHE[$key];
		}
		
		// Cache the out put of the call
		self::$CACHE[$key] = call_user_func_array(array('self', $func), $args);
		
		return self::$CACHE[$key];
	}
	
	/**
	 * Example cachable method
	 */
	public static function example()
	{
		return self::_cache('_example', func_get_args());
	}
	
	/**
	 * Actual method we are calling
	 */
	private static function _example($id)
	{
		$results = mysql_query('SELECT * FROM example_tbl');
		return $result;
	}
}

example.php

<?php
	// Not cached
	echo Example_Lib::example();

	// cached
	echo Example_Lib::example();