Refactoring #2

In this article we are summarizing the most interesting parts of:

Martin Fowler - Refactoring (2018) Chapter 3 "Bad Smells in Code"

This chapter helps us to detect bad code practices:

Mysterious name

you can't think of a good name for something
you are often afraid to rename things
solution a good name can save you hours

Duplicated code

solution unify code with the same structure

Long function

solution long term software is written in short functions

Long parameter list

solution depend on objects and not on attributes

Divergent change

every time there is a new user type, then I'll have to change these three/four functions
solution reduce coupling by joining similar functions together and consider them a new module

Primitive obsession

a telephone is more than a collection of characters
a url is more than a string
solution move those primitive types to it's own meaningful types

Repeated switches

if the same switch/case or if/else structure is repeated many times.
solution we should consider replace conditional with polymorphism.

Speculative Generality

over engineering a feature is very common
solution get rid of functions that handles things that aren't required yet

Middle man

is common that a class ends up delegating much of it's behavior to other classes
solution remove those classes and replace them with the actual functionality

Data class

solution instead of having classes with only fields, getters and setters, use interfaces or types

Top comments (2)

Dejan Fajfar • Jul 20

A nice list. Some items are quite hard to achieve and could be more trouble than it is worth. But non the less a worthy goal to strive for

Mashcuy Lab • Jul 20

Thank you! I view these guidelines as helpful reminders. Nowadays It's easy to get lost in the complexities of architectures, frameworks, APIs, and AI, and overlook the fact that software is ultimately built one small feature at a time. This is where these code smells become crucial. Martin Fowler did an excellent job of highlighting the most essential cases and I highly recommend his book.