Here’s a freebie that can be used immediately without any supporting libraries. This will be available in the near future in my opensource php framework: tgsf It’s released under the GPLv3.

Use it like this:

<?php

for ( $ix = 0; $ix < 10; $ix++ )
{
	echo alternateNs( 'one', '1','2' ) . PHP_EOL;
	echo alternateNs( 'two', 'a','b' ) . PHP_EOL;
}

And here is the function:

<?php

/**
* Alternate with a namespace
* The first argument is a namespace to enable multiple calls in a single loop
* Call with a set of arguments and this function will return them based on a modulus of the quantity of invocations
* in other words, each time you call this function it will return the next item in the list of parameters.
* to reset, call with a namespace and different arguments
*/
function alternateNs()
{
	$args = func_get_args();
	$ns = array_shift( $args );
	$argCnt = count($args);

	if ( empty( $ns ) )
	{
		throw new Exception( 'alternateNs called without a namespace' );
	}

	static $cache = array();

	if ( empty( $cache[$ns] ) )
	{
		$cache[$ns]['current'] = 0;
		$cache[$ns]['items'] = array();
	}

	$items =& $cache[$ns]['items'];
	$current =& $cache[$ns]['current'];

	if ( ! ( $items === $args ) || $argCnt == 0 )
	{
		$current = 0;
		$items = $args;
	}
	else
	{
		$current++;
	}

	return $argCnt>0?$args[$current % $argCnt]:'';
}