Fifty Shades of OOP
OOP-bashing seems fashionable nowadays. I decided to write this article after seeing two OOP-related articles on Lobsters in quick succession. I’m not interested in defending or attacking OOP, but I do want to throw in my two cents and offer a more nuanced view.
The industry and the academy have used the term “object-oriented” to mean so many different things. One thing that makes conversations around OOP so unproductive is the lack of consensus on what OOP is.
What is Object-Oriented Programming? Wikipedia defines it as “a programming paradigm based on the concept of objects.” This definition is unsatisfactory, as it requires a definition of an “object” and fails to encompass the disparate ways the term is used in the industry. There is also Alan Kay’s vision of OOP . However, the way most people use the term has drifted apart, and I don’t want to fall into essentialism or etymological fallacy by insisting on a “true” meaning.
Instead, I think it is better to treat OOP as a mixed bag of interrelated ideas and examine them individually. Below, I will survey some ideas related to OOP and mention their pros and cons (in my subjective mind).
Classes
Object-oriented programming is a method of implementation in which programs are organized as cooperative collections of objects, each of which represents an instance of some class, and whose classes are all members of a hierarchy of classes united via inheritance relationships. — Grady Booch
Classes extend the idea of a “struct” or “record” with support for the method syntax, information hiding, and inheritance. We will talk about those specific features later.
Classes can also be viewed as blueprints for objects. It is not the only way to do that, and prototypes is an alternative pioneered by Self and, most famously, used by JavaScript. Personally, I feel that prototypes are harder to wrap one’s head around compared to classes. Even JavaScript tries to hide its usage of prototypes from newcomers with ES6 classes.
When I learned JavaScript, prototype inheritance and the semantics of this were two of the topics I struggled with the most.
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