Chapter 7 - Refactoring

Question 1

What is the Motivation of Refactoring?

Answer 1

es gibt 3 Stellschrauben: Deadline, External Quality (Features) und Internal Quality (Code, sieht der Kunde nicht) wobei oft nur 2 von 3 anpassbar sind. Code wird öfter gelesen als geschrieben, oft aktueller als documentation

Question 2

What is Refactoring?

Answer 2

improvement of the internal structure without changing external behavior, longevity (langlebigkeit) of software requires continuous improvement

Question 3

How is refactoring done?

Answer 3

carried out in small steps, test cases safeguard the correctness of transformations, if there are no tests: write them at first!

Question 4

Why might Refactoring be necessary?

Answer 4

adding functionality leads to duplicate code (unabsichtlich da Entwickler evtl. nicht ganzen Code kennt) –> Refactoring

Question 5

When should Refactoring be done?

Answer 5

beim dritten Mal wo man über das Problem stolpert

Question 6

What are problems with refactoring?

Answer 6

leads to Indirection (Umweg): nice code but bad performance –> 90/10 rule (90% of runtime is spent for 10% code)

Question 7

Explain “Bad Smells”

Answer 7

when is design bad? Code metrics do not really help (e.g. inheritance depth of 3 might be worse or of 7 might be still okay…)

Question 8

Name Bad Smells Indicators

Answer 8

Duplicate Code, Long methods, Switch statements, Comments

Question 9

Explain “Refactoring to Patterns”

Answer 9

introduce patterns while refactoring, e.g. null object