I have been doing some reading this week. I start reading Cruise Engine source, and looked around for older objectifications on side, starting with AGI engine. After seeing how the old objectifications were made, I began to question my approach to the project.
I was thinking to read all the engine code, before determining the classes etc. But as far as I saw, AGI was objectified step by step, objectifying one file in the step, and modifying only the ones that needs to. This method makes more sense to me considering several reasons.