Python distilled
David Beazley
Improving existing code - refactoring - is one of the most common tasks you'll face as a programmer. This book teaches you clear and actionable refactoring rules that you can apply without relying on intuitive judgments such as “code smells.” Following the author's expert perspective - that refactoring and code smells can be learned by following a concrete set of principles - you'll learn when to refactor your code, what patterns to apply to what problem, and the code characteristics that indicate it's time for a rework.