Clean Design. The Practice of Empirical Software Design

Dirty code creates problems. To make the code easier to read, it is necessary to clean it up by breaking it into parts that are convenient to work with. Kent Beck, the creator of extreme programming methodology and a pioneer in design patterns, tells us where and when it is best to conduct cleanup to improve the code considering the overall structure of the system.
The book does not force the reader to clean everything at once; instead, it allows testing several examples that fit the task at hand. You will learn how to logically divide a large function containing many lines of code into parts. You will become acquainted with theoretical concepts of software design: coupling, cohesion, discounted cash flows, and variability.