Posted on Jul 4, 2022 • Originally published at maximilianocontieri.com

Refactoring 007 - Extract Class

#javascript #webdev #beginners #tutorial

Behavior is repeated across the system. But we are missing a concept

TL;DR: Put together what belongs together

Problems Addressed

Code Duplication
Missing Abstraction
Low Cohesion

Related Code Smells

Code Smell 124 - Divergent Change

Maxi Contieri ・ Mar 24 '22

Code Smell 143 - Data Clumps

Maxi Contieri ・ Jun 22 '22

#webdev #javascript #beginners #programming

Steps

Extract the methods (and accidentally the properties) coupled into a new concept
Use the new concept

Sample Code

Before

 final class Person { private String name; // Below cohesive properties private String homeAreaCode; private String homeNumber; public String name() { return name; } // Below cohesive behaviour public String telephoneNumber() { return ("(" + homeAreaCode + ") " + homeNumber); } String areaCode() { return homeAreaCode; } String officeNumber() { return officeNumber; } }

After

// 1. Extract the methods (and accidentally the properties) coupled into a new concept  public class TelephoneNumber { private String number; private String areaCode; public String telephoneNumber() { return ("(" + areaCode + ") " + _number); } public String areaCode() { return areaCode; } public String number() { return number; } } final class Person { private String name; // 2. Use the new concept private TelephoneNumber officeTelephone = new TelephoneNumber(); public String name() { return name; } public String telephoneNumber(){ return officeTelephone.getTelephoneNumber(); } }

Type

[X] Automatic

Most IDEs implement this safe refactor.

Why code is better?

Logic code is in just one place together with its rules

Credits

Image from drpepperscott230 on Pixabay

This article is part of the Refactoring Series

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