## *Setters violate immutability and add accidental coupling*

> TL;DR: Make your attributes private to favor immutability

# Problems Addressed

* Mutability
* setXXX() violates good naming policies since it does not exist on the [MAPPER](https://hackernoon.com/what-is-wrong-with-software-uh8j3y7k)
* Accidental [coupling](https://hackernoon.com/coupling-the-one-and-only-software-designing-problem-9z5a321h)

# Related Code Smells

* [Code Smell 28 Setters](https://maximilianocontieri.com/code-smell-28-setters)
* [Code Smell 01 Anemic Models](https://maximilianocontieri.com/code-smell-01-anemic-models)

# Steps

1. Locate the setters usage
2. If you are setting essential properties move them to the constructor and remove the method
3. If you need to change an accidental property it is not a setter. Remove the setXXX prefix

# Sample Code

## Before

```java
public class Point {
   protected int x;
   protected int y;
  
   public Point() {
        this.x = 0;
        this.y = 0;        
   }
    
   public void setX(int x) {
	this.x = x;
   }
  
   public void setY(int y) {
        this.y = y;
  } 
}

Point location = new Point();
//At this momment, it is not clear which points represent
//It is coupled to constructor decision.
//Might be null or some other convention

location.setX(1);
//Now we have point(1,0)

location.setY(2);
//Now we have point(1,2)
```

```java
public class Car {
   protected int speed;
  
   public Car() {     
   }
    
   public void setSpeed(Speed desiredSpeed) {
	this.speed = desiredSpeed;
   }   
}

Car tesla = new Car();
//We have no speed??

tesla.setSpeed(100 km/h);
//Now our car runs fast
```

## After

```java
//1. We locate setters usage
location.setX(1);

location.setY(2);

//2. If you are setting essential properties move 
//them to the constructor and remove the method
public class Point {
   public Point(int x, int y) {
        this.x = x;
        this.y = y;        
     //We remove the setters
   }

Point location = new Point(1, 2);
```

```java
public class Car {
   protected int speed;
  
   public Car() {    
     this.speed = 0 km/h;
   }
    
   public void speed(Speed desiredSpeed) {
	    this.speed = desiredSpeed;
   }   
}


//1. Locate the setters usage
//3. If you need to change an accidental property
// it is not a setter. Remove the setXXX prefix


Car tesla = new Car();
//Our car is stopped

tesla.speed(100 km/h);
//We tell the desired speed. We don't set anything
//We don't care if the car stores its new speed.
//if it manages through the engine
//if the road is moving etc
```

# Type

\[ X \] Semi automatic

\
We should detect setters (unless they use meta programming) with our IDEs.

We can also remove them and see which tests fails if we have good coverage

# Tags

* Mutability

# Related Refactorings

* Remove Getters
* Pass essential properties in the constructor
* Initialize essential properties in the constructor

  \

\


Tesla

Winner of Noonies 2020 for the award Hacker Noon Contributor of the Year - REFACTORING.

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Nominated for 2022 - HackerNoon Contributor of the Year - Refactoring

Nominated for 2022 - HackerNoon Contributor of the Year - Quality Assurance

Nominated for 2022 - HackerNoon Contributor of the Year - Github

Nominated for 2022 - HackerNoon Contributor of the Year - Machine Learning

Nominated for 2022 - HackerNoon Contributor of the Year - Clean Code

Nominated for 2022 - HackerNoon Contributor of the Year - Software Architecture

Nominated for 2022 - the Greatest Storyteller

Nominated for 2022 - HackerNoon Contributor of the Year - Debugging

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Refactoring: Remove Setters #CodeSmell

Refactoring: Remove Setters #CodeSmell

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