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Michael C. Feathers
The average book on Agile software development describes a fairyland of greenfield projects, with wall-to-wall tests that run after every few edits, and clean & simple source code.
The average software project, in our industry, was written under some aspect of code-and-fix, and without automated unit tests. And we can't just throw this code away; it represents a significant effort debugging and maintaining. It contains many latent requirements decisions. Just as Agile processes are incremental, Agile adoption must be incremental too. No more throwing away code just because it looked at us funny.
Mike begins his book with a very diplomatic definition of "Legacy". I'l skip ahead to the undiplomatic version: Legacy code is code without unit tests.
Before cleaning that code up, and before adding new features and removing bugs, such code must be de-legacified. It needs unit tests.
To add unit tests, you must change the code. To change the code, you need unit tests to show how safe your change was.
The core of the book is a cookbook of recipes to conduct various careful attacks. Each presents a particular problem, and a relatively safe way to migrate the code towards tests.
Code undergoing this migration will begin to experience the benefits of unit tests, and these benefits will incrementally make new tests easier to write. These efforts will make aspects of a legacy codebase easy to change.
It's an unfortunate commentary on the state of our programming industry how much we need this book.
Udo Zölzer, Xavier Amatriain, Daniel Arfib, Jordi Bonada, Giovanni De Poli, Pierre Dutilleux, Gianpaolo Evangelista, Florian Keiler, Alex Loscos, Davide Rocchesso, Mark Sandler, Xavier Serra, Todor Todoroff
* Digital Audio Effects (DAFX) covers the use of digital signal processing and its applications to sounds * Discusses digital audio effects from both an introductory level, for musicians, and an advanced level, for signal processing engineers * Explains what can be done in the digital processing of sounds in the form of computer algorithms and sound examples resulting from these transformations * Brings together essential DSP algorithms for sound processing, providing an excellent introduction to the topic