If the state is encapsulated somewhere else, why is it no longer OOP? I don’t think Alan Kay would say that having each object simply be a handle into a table of values meant they could no longer be called objects. Heck, if we take the FactoryFactory example as being the bad thing about OOP, and consider that this comes from the GoF design pattern book, there is already a pattern in that book that closely resembles ripping the state out of an object and putting it somewhere else. Again, it is definitely not strawman OOP, but not very many programming systems are, especially modern ones.

Encapsulation in OOP terms means the state is encapsulated with the logic that fetches / mutates it. ECS explicitly is designed to do the opposite. It’s really that simple.

The issue isn’t about how you store the objects but about whether the framework logically encapsulates object data with its associated logic.

> Encapsulation in OOP terms means the state is encapsulated with the logic that fetches / mutates it.

No it doesn't. 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. 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 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".