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OOP is encapsulation, inheritance, and polymorphism. Polymorphism maps to behaviour which is type-based, but usually also based on the objects internal/mutable

OOP is encapsulation, inheritance, and polymorphism. Polymorphism maps to behaviour which is type-based, but usually also based on the objects internal/mutable state. This is no surprise since OOP came out of Simula for doing simulations.

vips7L 2y ago
I really disagree. You don’t need polymorphism or inheritance. The core of OOP is objects and encapsulation. Putting behaviour next to the data. It has nothing to do with mutability.
- layer8 2y ago
  Regarding your first point, OOP without subtyping has typically been referred to as object-based rather than object-oriented.
  - vips7L 2y ago
    Sure, I just think that’s being pedantic.
    - layer8 2y ago
      I think it’s an important distinction, in particular since a significant number of people opine that subtyping is harmful, but encapsulation is not.
      - vips7L 2y ago
        I don’t particularly think subtyping is harmful. It can be misused, but everything in programming can be misused.
layer8 2y ago
Referring to my GP comment, subtyping subsumes inheritance and polymorphism. It is orthogonal to mutability. As an illustrative example, the Java Collection Framework makes significant use of inheritance and polymorphism, but could as well be reduced to immutable collections.