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OOP and Atomic Scripts
Updated 7 months ago
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What is an Atomic Script?
An Atomic Script is a Script wich manage specific behaviours, or attributes.
An Atomic Script have those attributes:
  • Is Indipendent.
  • Manage a specific behaviour or set of attributes.
  • Don't expose attributes, but methods wich operates on attributes.

From Object Oriented Programming to Game Development

In OOP Programming is a common way to define common behaviours and attributes on a single prototype class, and customize them on the classes wich extends it.
This way helps the developer to make the code more readable and more maintainable.
Take this example, we needs to define a class for a Cat, and a Class for a Dog:
class Cat { private int age; private string name; private void MakeNoise() { // do some mews } } class Dog { private int age; private string name; private void MakeNoise() { // do some doggo noises } }
Ok so, what's wrong here? Nothing for the moment, but imagine than you want to define a new behaviour wich might be used by the Cat class or the Dog class, you need to define it twice:
class Cat { private int age; private string name; private void MakeNoise() { // do some mews } private void MakeHardNoise() { // do some creepy mews } } class Dog { private int age; private string name; private void MakeNoise() { // do some doggo noises } private void MakeHardNoise() { // do some creepy doggo noises } }
This isn't a good way to develop, because every time you need to update a behaviour, or a set of attributes shared by multiple classes, you need to update each one! What a pain!
So, what's the solution?
The solution is to define generic classes, wich could be overrided by secondary classes like this:
class DomesticAnimal { private int age; private string name; public void init(_name: string, _age: int) { this.name = _name; this.age = _age; } private void MakeNoise() { // do some noise alert(name + " is noising"); } private void MakeHardNoise() { // do some creepy noise alert(name + " is hard noising"); } } class Cat extends DomesticAnimal { private override void MakeNoise() { alert(name + " says meow"); } } class Dog extends DomesticAnimal{ private override void MakeNoise() { MakeHardNoise(); // cause dogs make hard noises } }
Ok so, where's the magic here? We have now a generic class called DomesticAnimal, wich defines each behaviours and attributes of a DomesticAnimal, and 2 subclasses wich extends DomesticAnimal.
So every time we define new attributes or behaviours on a DomesticAnimal, all subclasses will receive the edit, and we don't have to manage all the classes with the same behaviours:
class DomesticAnimal { private int age; private string name; private bool noiseDescription; public void init(_name: string, _age: int) { this.name = _name; this.age = _age; this.noiseDescription = _name + " of age " + _age + " is making some noises"; } private void MakeNoise() { // do some noise alert(noiseDescription); } private void MakeHardNoise() { // do some creepy noise alert(noiseDescription); } } class Cat extends DomesticAnimal { private override void MakeNoise() { alert(noiseDescription + ", says meow"); } } class Dog extends DomesticAnimal{ private override void MakeNoise() { alert(noiseDescription + ", says woff"); } }
Wow cool, so you can edit one single class and each subclasses will be updated!

Back to Atomic Scripts

So, how can we use this in Game Development? And how Atomic Scripts are related to OOP?
Basically is the same, in Game Development you need to separate atomic behaviours, take this example:
A player have some controllers:
  • A Movement Controller
  • An Animation Controller
  • A Sound Controller
  • Other Controllers, like UI or Networking
We can define each behaviours inside a single script, like this:
class PlayerGenericController { // attributes void Update() { if(Input.GetKey(A key)) { // do some stuffs, for example a movement // manage movements ManageMovements(); // manage animations ManageAnimations(); // manage sounds ManageSounds(); // manage others ManageOthers(); } } }
This is absolutely wrong! There are multiple reasons:
a) Physics behaviours needs to be called on different frame related update methods (like FixedUpdate), instead of Sounds or Animations behaviours, wich could be called on the Update method.
b) You don't define a readable code, at the start of the project it could be clean, but after developments it could become really big and unreadable, because all the logics are defined here.
c) You don't have control of your issues, if the logic is all inside a single script it's hard to debug and error, or an invalid behaviour.
d) Performance, in a single script you define a set of instructions to execute, and the runtime processor need to execute all of them. If any of these is slower than the others, the execution might be really slow and result might be not as expected.
So how can we fix that? Is really simple, create and Atomic Script for each main behaviour, for example:
[RequireComponent(typeof(PlayerMotorController))] [RequireComponent(typeof(PlayerAnimatorController))] [RequireComponent(typeof(PlayerSoundController))] class Player { private float movementSpeed = 10.0f; void Awake() { this.GetComponent<PlayerMotorController>().SetMovementSpeed(this.movementSpeed); // set the motor velocity } } class PlayerMotorController { // attributes private void movementSpeed; public void SetMovementSpeed(float _movementspeed) { this.movementSpeed = _movementSpeed; } void FixedUpdate() { if(Input.GetKey(KeyCode.W)) { // move forward myRigidBody.velocity = new Vector3(movementSpeed, 0, 0); } // manage other movements here } } class PlayerAnimatorController { // attributes void Update(){ myAnimator.setBool("isWalking",Input.GetKey(KeyCode.W) != 0); } } class PlayerSoundController { // attributes void Update() { if(Input.GetKey(KeyCode.W)) { PlayWalkSound(); } } private void PlayWalkSound() { mySound.play("walkClip"); } }
Ok so the Player class define some required componets, wich must be added to a Player GameObject, and it sets some attributes on controllers.
The player Controller are Atomic Scripts wich defines the behaviours to execute, and how to execute.
This makes the code more readable and maintainable, if in the future you need to add some edits on the Motor behaviours, you can edit only the PlayerMotorController script, and not all the Player script.
You can also define atomic attributes, so the PlayerMotorController will define only the attributes for movements, and the sound controller the attributes for sound management.
This will help you make your inspector more clean and readable.
Remember than those scripts are:
  • Indipendents: each script will work without others, a movement controller doesn't need a sound controller
  • Each script define a set of Behaviours and Attributes for a specific main behaviours
  • Don't expose attributes, but methods wich operates on attributes, for example to set a PlayerMotorController movementSpeed you can't access it directly, but using the exposed method SetMovementSpeed. This helps you manage some special cases inside the controller itself (for example negative values or other issues), and let to the controller the entire management of it's attributes.

Conclusions

So, after this long explanation, the reasons why Atomics Scripts are useful are the follwing:
  1. More readable, mainteinable code
  2. Less code for each scripts
  3. More readable Inspector attributes
  4. More class protection
  5. Error handling improved

Nicola
Unity Developer - iOS Developer - Programmer
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