OOP Isn't a Fundamental Particle of Computing

The biggest change in programming over the last twenty-five years is that today you manipulate a set of useful, flexible data types, and twenty-five years ago you spent a disproportionately high amount of time building those data types yourself.

C and Pascal--the standard languages of the time--provided a handful of machine-oriented types: numbers, pointers, arrays, the illusion of strings, and a way of tying multiple values together into a record or structure. The emphasis was on using these rudiments as stepping stones to engineer more interesting types, such as stacks, trees, linked lists, hash tables, and resizable arrays.

In Perl or Python or Erlang, I don't think about this stuff. I use lists and strings and arrays with no concern about how many elements they contain or where the memory comes from. For almost everything else I use dictionaries, again no time spent worrying about size or details such as how hash collisions are handled.

I still need new data types, but it's more a repurposing of what's already there than crafting a custom solution. A vector of arbitrary dimension is an array. An RGB color is a three-element tuple. A polynomial is either a tuple (where each value is the coefficient and the index is the degree) or a list of {Coefficient, Degree} tuples. It's surprising how arrays, tuples, lists, and dictionaries have eliminated much of the heavy lifting from the data structure courses I took in college. The focus when implementing a balanced binary tree is on how balanced binary trees work and not about suffering through a tangled web of pointer manipulation.

Thinking about how to arrange ready-made building blocks into something new is a more radical change than it may first appear. How those building blocks themselves come into existence is no longer the primary concern. In many programming courses and tutorials, everything is going along just fine when there's a sudden speed bump of vocabulary: objects and constructors and abstract base classes and private methods. Then in the next assignment the simple three-element tuple representing an RGB color is replaced by a class with getters and setters and multiple constructors and--most critically--a lot more code.

This is where someone desperately needs to step in and explain why this is a bad idea and the death of fun, but it rarely happens.

It's not that OOP is bad or even flawed. It's that object-oriented programming isn't the fundamental particle of computing that some people want it to be. When blindly applied to problems below an arbitrary complexity threshold, OOP can be verbose and contrived, yet there's often an aesthetic insistence on objects for everything all the way down. That's too bad, because it makes it harder to identify the cases where an object-oriented style truly results in an overall simplicity and ease of understanding.

(Consider this Part 2 of Don't Distract New Programmers with OOP. There's also a Part 3.)

permalink November 13, 2012

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