Recursion...

oop-recursion.php

<?php

	/**
	 * Accept an array of instances of 
	 * MenuService. Each will process their
	 * input data then return their output 
	 * data so the next instance can use 
	 * the output data as their input data. 
	 * When there is no instance left in 
	 * the array, the last one shall be returned
	 * 
	 * @return self
	 */
	public function prepend(){

		$remainingMenuSvcs = func_get_args();

		$currentMenuSvc = array_shift($remainingMenuSvcs);
		
		if ($this->mainInstance === null) {
			$this->mainInstance = $this;
			$remainingMenuSvcs[] = $this->mainInstance;
		} 

		if (count($remainingMenuSvcs) > 0) {

			$nextMenuSvc = $remainingMenuSvcs[0];

			$msData = $currentMenuSvc->execute()->prepareResponse();

			$nextMenuSvc->setCode($msData['code']);
			$nextMenuSvc->setInputData($msData['data']);
			$nextMenuSvc->setMainInstance($this->mainInstance);

      			//Calls prepend again...
			return call_user_func_array([$nextMenuSvc, 'prepend'], $remainingMenuSvcs);
		}

		return $this;
	}

setMainInstance was solely made for this function.

call_user_func_array

but why