[TYPO3-mvc] Thoughts regarding inter-extension communication

[Joerg Schoppet]

Hi,

Prerequisite:
everything extbase-dependant

following scenario:
I wrote a general billing extension. And created a be-module, in which I 
can create positions and finally invoices.

Now I have additional extensions, which should "hook" into the billing 
extension to provide "specialized" billing-positions.

Actual solution:
In the billing-extension I created an own class, which is a singleton 
and has a method called "registerExtension". All the specialized 
extensions have a call in ext_tables.php, which registers an own class 
as a string:
$obj = t3lib_div::makeInstance('Tx_JrCustomer_Utility_Billing');
$obj->registerExtension('Tx_JrDomainManagement_Utility_Billing');

In the class from the billing-extension I can then call the following 
method:
         public function fetchBillings($year, $month) {

                 foreach ($this->billings as $extension) {
                         $obj = t3lib_div::makeInstance($extension);
                         $this->positions = 
array_merge($this->positions, $obj->fetchPositions($year, $month));
                 }

         }


What I don't like at this solution is:
When ext_tables.php is executed the extbase-dispatcher is not loaded, so 
I have to use "require_once"-call for the main class in ext_tables.php.
Because of this I also have to register the specialized classes as 
strings, so that I haven't to include this all with require_once.


Is there a better solution for this usecase? Perhaps something 
completely different?

Joerg