> No it doesn't. Yes, yes it does. > There are plenty of examples in OO where that isn't true or no physics engine that's been build in the last two decades w

> No it doesn't. Yes, yes it does. > There are plenty of examples in OO where that isn't true or no physics engine that's been build in the last two decades would work at all. It would be surprising if most physics engines were built in an object-oriented way. The only one I'm familiar with, ODE, certainly isn't object-oriented. > The only core thing needed for OO is that objects have unique identities that then enable a notion of associated state at all. A pure system would not allow for an unbounded number of unique identities at all, you would not really be able to talk about objects at all (or entities or whatever object synonym is preferred). No, objects in OOP have not just their own unique identities but have their own behavior. Encapsulation is the most fundamental pillar of object-oriented programming. Without that, any procedural C code that makes use of structs could be called object-oriented, since structs would then be synonymous with "objects".