September 3, 2016

Object-Oriented Programming: A Disaster Story

  —A look at object-oriented programming when it goes wrong.

Read Object-Oriented Programming: A Disaster Story, not so much for what it said but for what ended up on Reddit. If you are looking for perspectives on object-oriented programming, the comments are a good read.

One commenter, discussed Closures and Objects are Equivalent, another brought in Alan Kay on Object-Oriented Programming. Both reasonable responses.

In my opinion, the best comment:

The value of objects is in treating systems behaviourally. Inheritance and even immutability are orthogonal. An object is a first-class, dynamically dispatched behaviour.   (/u/discretevent)

The lesson, is know your tools, use them appropriately and recognize their limitations. Orthogonality is a good way to organize your thinking on this.

In Object-Oriented Programming: A Disaster Story,  I do agree that shallow object hierarchies are better than deep but I'm not sure if the argument presented there is in response to programs that derive all classes from the same object or and argument against deep class hierarchies.

With respect to

Among OOP practitioners, there are competing schools of thought on the degree to which a program’s behaviors should be expressed as class methods rather than free-floating functions.

Isn't the correct answer to apply what is appropriate to the context?

I've made arguments wherein a free-floating function is the best tool for ensuring consistency between different classes whose behaviour is related only due to business rules and logic. For example. do you want a manager class in an automobile that ensures the lights are on and the doors are locked while driving? You can construct arguments for both approach.

The right approach is the one that leads to the simplest implementation. In this case, I agree with the author and avoid "nonsense Doer" classes.

There is a great set of comments in the Reddit thread relating to context and object decomposition.