Code Smell 68 - Getters

How to avoid getters

6 May, 2023

Contributors

Maxi Contieri

@mcsee

TL;DR: How to avoid getters

Getting things is widespread and safe. But it is a very bad practice.

Problems

Naming
Information Hiding
Coupling
Encapsulation Violation
Mutability
Anemic Models

Solutions

Avoid Getters
Use domain names instead
Protect your implementation decisions.

Sample Code

Wrong

<?php

final class Window {
    public $width;
    public $height;
    public $children;

    public function getWidth() {
        return $this->width;
    }

    public function getArea() {
        return $this->width * $this->height;
    }

    public function getChildren() {
        return $this->children;
    }
}

Right

<?php

final class Window {
    private $width;
    private $height;
    private $children;

    public function width() {
        return $this->width;
    }

    public function area() {
        return $this->height * $this->width;
    }

    public function addChildren($aChild) {
        // Do not expose internal attributes
        return $this->children[] = $aChild;
    }
}

Detection

Getters coincide in certain scenarios with a true responsibility. It will be reasonable for a window to return its color and it may accidentally store it as color. so a color() method returning the attribute color might be a good solution.

getColor() breaks bijection since it is implementative and has no real counterpart on our mappers.

Most linters can warn us if they detect anemic models with getters and setters.

Conclusion

Getters and Setters are a bad established practice. Instead of focusing on object behavior (essential), we are desperate to know object guts (accidental) and violate their implementation.