Objects created without arguments are often mutable and erratic

TL;DR: Pass all your essential arguments when creating objects.

Problems

• Mutability

• Anemic Models

Solutions

1. Use one complete and single constructor.

2. Avoid Setters and Getters

Context

It is common usage using a zero-argument constructor and a bunch of setters to change it.

Beans is a well-known example of this code smell.

Sample Code

Wrong

 public Person();

// Anemic and mutable

Right

public Person(String name, int age){
     this.name = name;
     this.age = age;
     } 
 }

// We 'pass' the essence to the object 
// So it does not mutate

Detection

[X] Automatic

We can check all constructors, but there are some false positives.

Stateless objects are a valid example.

Tags

• Mutability

Conclusion

Empty constructors are mutability hints and accidental implementation issues.

We need to research usages to improve our solutions.

Relations

Code Smell 68 - Getters

Maxi Contieri ・ Apr 29 '21 ・ 2 min read

#codenewbie #tutorial #oop #programming

Code Smell 28 - Setters

Maxi Contieri ・ Nov 19 '20 ・ 2 min read

#oop #codenewbie #programming #webdev

Code Smell 01 - Anemic Models

Maxi Contieri ・ Oct 20 '20 ・ 2 min read

#codenewbie #oop #beginners #computerscience

More Info

• Nullary Constructor

• Nude Models — Part I : Setters

• Nude Models — Part II : Getters

• The Evil Power of Mutants

Credits

Photo by Ade Adebowale on Unsplash