Showing posts from September, 2015

Moving Sideways with Lateral Abstractions?

When I'm doing design and refactoring, part of me worries that I'm just creating a mess of objects and classes. One of the kinds of mess that I feel I make the most are lateral abstractions. What I mean by lateral abstraction is an abstraction that is at the same level as the code I abstracted it out of. It doesn't add very much to the conversation, and it doesn't introduce a finer vocabulary than was already there. When looking over the code I wrote in Writing a Better Code Narrative, I get a slight feeling in the back of my head that some of that code is lateral abstraction.

Without re-posting all of the code (which can be found here), I started with a CommandParser class that read a string of character commands and "executed" those commands to produce a new output string. The original code was intentionally hairy, but I refactored it down into a series of Command classes to encapsulate the individual behaviors, and a CommandFactory to encapsulate the algor…

Two Great Takeaways from GOOS

I recently just finished reading Growing Object-Oriented Software, Guided by Tests (or GOOS for short) by Nat Pryce and Steve Freeman. I highly recommend every developer pick up a copy and give it a read. It is full of great advice for building a well-tested, high quality application. I wanted to pick out two particular gems I found towards the end of the book that I felt are really powerful.

[W]e like to have names for the relationships between objects as well as objects themselves. As the legends say, if we have something's true name, we can control it.– Growing Object-Oriented Software Guided by Tests, page 244 (authors' emphasis)

They are talking specifically about preferring to mock interfaces rather than concrete implementations, but this concept bubbles up generally throughout the book. They use interfaces extensively, even noting that their use is above average, to tease out concepts and relationships in the code. Many in the community feel that interfaces are just need…