recently I was wondering if there are any best practices for designing an expert routine within a transformation in SAP BW. We've decided to use a central class for all transformations and call the corresponding method within the expert routine. This allows us to change the source code of the expert routine without having to reactivate the transformation and DTP again after changes. It also brings all features of ABAP oop. Speaking of ABAP oop I asked myself if it was better to use static methods for these transformation routines instead of instance methods. So far we're creating an instance of the class in the expert routine. But doesn't this affect the runtime if a new object has to be created whenever a new data package is running during the transformation? Please let me know what you're thinking of this. I've learned to use instance methods by default but right now this doesn't make too much sense for me anymore. Are there best practices?