Interfaces – The Most Important Software Engineering Concept

Hi, I'm the author. I submitted this yesterday, but I didn't even get 1 upvote, so I'm glad to see it here today as I think it is a very important topic for discussion. Feedback from the submission on Reddit has suggested that this article is too long which I now acknowledge. I'd be happy to hear any critiques you have.

Awesome write up.

While I agree that dynamically typed languages -- by their loosely defined API requirements -- are more difficult to scale, it's not difficult to add type checking and/or provide a well structured public API where necessary.

I think statically typed languages go too far in the other direction. Tyr type and API definitions are too strict leading in a ton of unnecessary effort (ie boilerplate), increased surface area for potential bugs, and overly restrictive limits that require 'creative' workarounds to effectively write code.

I think there's a 'happy medium' to be found where type checks are required for certain inputs and a clearly defined API can be established without the need for private/internal/public syntax artifacts.

I've been playing with this a bit in JS lately. Using model definitions to specify the structure and enforce validation. As well as defining facades with the ES6 module import/export syntax to define public APIs. Finer grained control (ie private vs internal) can be defined using closures that provide internal interactions while hiding the private implementation details.

Good article. Interfaces and modularity are core concepts, worthy of much attention. Especially questions like how to do functional decomposition, finding the right abstractions, and good interface design.

I'll chew on your statements about the success of Python. Though my first love was LISP, I'm now far more comfortable leaning on static typing and composition.

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The best book on software design I've ever read was written by two economists.

Design Rules: The Power of Modularity

http://www.amazon.com/Design-Rules-Vol-Power-Modularity/dp/0...

This book didn't change how I program so much as changed how I think. Like the difference between making and criticizing art. Whereas SICP gave me new mental models, Design Rules gave me new philosophies. More like Design of Everyday Things did.

I think coupling and cohesion stand out as fundamental software design principles. (I wouldn't say it's "interfaces" as I can imagine interfaces with tight coupling or low cohesion.)

This article would have helped tremendously back when I was struggling to wrap my head around the purpose of interfaces. Great visualizations and certainly a very unique but also a very logical way of looking at interfaces. Great article.