[mostlylurks]

> OOP is about building sub programs with their own state and behaviours, yet implementing a common interface so they can still effectively communicate to each other.

This doesn't seem like a sufficient definition, as closures are also sub programs with their own state and behaviors that implement a common interface (the function signature), and you'd have to stretch the definition of OOP to the point of meaninglessness if that would be sufficient to qualify as OOP.