Refactoring: Improving the Design of Existing Code (Addison-Wesley Signature Series (Fowler))

by Martin Fowler

To avoid digging your own grave, refactoring must be done systematically.

For much of the history of software development, most people believed that we design first, and only when done with design should we code. Over time, the code will be modified, and the integrity of the system—its structure according to that design—gradually fades. The code slowly sinks from engineering to hacking.

Yet the cumulative effect of these small changes can radically improve the design. It is the exact reverse of the notion of software decay.

Whenever I do refactoring, the first step is always the same. I need to ensure I have a solid set of tests for that section of code.

this understanding is in my head—a notoriously volatile form of storage.