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OOP Without Classes?

  • Palo Alto, CA
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I interviewed David West, the author of the Object Thinking book, a few weeks ago, and he said that classes were not meant to be in object-oriented programming at all. He actually said that earlier; I just didn't understand him then. The more I've thought about this, the more it appears obvious that we indeed do not need classes.

Battleship Potemkin (1925) by Sergei M. Eisenstein
Battleship Potemkin (1925) by Sergei M. Eisenstein

Here is a prototype.

Let's say we have only types and objects. First, we define a type:

type Book {
  void print();

Then we create an object (pay attention; we don't "instantiate"):

Book b1 = create Book("Object Thinking") {
  String title;
  Book(String t) {
    this.title = t;
  public void print() {
    print("My title: " + this.title);

Then we create another object, which will behave similarly to the one we already have but with different constructor arguments. We copy an existing one:

Book b2 = copy b1("Elegant Objects");

Libraries will deliver us objects, which we can copy.

That's it.

No implementation inheritance and no static methods, of course. Only subtyping.

Why not?