Veiko Schnabel writes:

.... i created a new Product calles book with propertys writer(string), pages(int) and a standart method called index_html to output all these probertys ....

.... instance "my_book" ....

<dtml-var my_book> .... all i get is the id of the instance my_book <PubClass instance at 8ab30c8>

The ZPublisher (i.e. when you access your instance with the internet) automatically activates "index_html" (if the object is not callable). "dtml-var" does not. Instead, it calls the object, if it is callable (not the case in your example), and then converts to a string. You can use: <dtml-with my_book> <dtml-var index_html> </dtml-with> Dieter